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{{Short description|Roman emperor from 306 to 337}}
{{Redirect|Constantine I|the third king of the modern Greek state|Constantine I of Greece||Constantine I (disambiguation)}}
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{{Use British English|date=July 2022}}
{{Use dmy dates|date=July 2024}}
{{Infobox royalty
| name         = Constantine
| image        = Statua di Costantino ai musei capitolini.jpg
| alt          = Head statue of Constantine the Great
| caption      = Head of the [[Colossus of Constantine]], [[Capitoline&nbsp;Museums]]
| succession   = [[Roman emperor]]
| reign        = 25 July 306 – 22 May 337 {{awrap|(alone from 19 September 324)}}
| predecessor  = [[Constantius I]] (in the West)
| successor    = {{ubl|[[Constantine II (emperor)|Constantine II]]|[[Constantius II]]|[[Constans I]]}}
| regent       = {{Collapsible list|title={{nobold|''See list''}}|
|[[Galerius]] (306–311){{efn|name=east|Emperor of the East}}
|[[Severus II]] (306–307){{efn|Emperor of the West}}
|[[Maxentius]] (306–312){{efn|name=unrec|In the West; unrecognised outside Italy}}
|[[Maximian]] (306–308, 310){{efn|name=unrec}}
|[[Licinius]] (308–324){{efn|Originally emperor of the West; became emperor of the East after 313.}}
|[[Maximinus II]] (310–313){{efn|name=east}}
|[[Valerius Valens|Valens]] (316–317){{efn|name=neow|In the East; nominal emperor of the West.}}
|[[Martinian (emperor)|Martinian]] (324){{efn|name=neow}}}}
| reg-type     = Co-rulers
| birth_name   = Flavius Constantinus
| birth_date   = 27 February 272
| birth_place  = [[Naissus]], [[Moesia Superior]], [[Roman Empire]]
| death_date   = 22 May 337 (aged 65)
| death_place  = Achyron, [[Nicomedia]], [[Bithynia]], Roman Empire
| burial_place = [[Church of the Holy Apostles]], Constantinople (remains now lost)
| spouses      = {{ubl|[[Minervina]]{{efn|Minervina may have been his [[concubine]].}}
|[[Fausta]]}}
| issue        = {{ubl|[[Crispus]]|[[Constantine II (emperor)|Constantine II]]|[[Constantius II]]|[[Constantina]]|[[Constans I]]|[[Helena (wife of Julian)|Helena]]}}
| issue-link   = #Illness and death
| full name    = Flavius Valerius Constantinus
| regnal name  = Imperator Caesar Flavius Valerius Constantinus Augustus
| dynasty      = [[Constantinian dynasty|Constantinian]]
| father       = [[Constantius Chlorus]]
| mother       = [[Helena, mother of Constantine I|Helena]]
| religion     = {{ubl|[[Ancient Roman religion]] (until 312)|[[Constantine the Great and Christianity|Christianity]] (from 312)}}
}}
'''Constantine I'''{{Efn|{{IPAc-en|ˈ|k|ɒ|n|s|t|ən|t|aɪ|n|,_|-|t|iː|n}} {{respell|KON|stən|tyne|,_|-|teen}}; {{langx|la|Flāvius Valerius Cōnstantīnus}}, {{IPA|la-x-classic|konstanˈtiːnus|lang|link=yes}}; {{Langx|grc-x-koine|Κωνσταντῖνος|Kōnstantînos}}}} (27 February 272{{spnd}}22 May 337), also known as '''Constantine the Great''', was a [[Roman emperor]] from AD&nbsp;306 to 337 and the first Roman emperor to convert to [[Christianity]].{{efn|With the possible exception of [[Philip the Arab]] ({{reign|244|249}}). See [[Philip the Arab and Christianity]].<ref>{{Cite book |last=Shahîd |first=Irfan |url= |title=Rome and the Arabs |date=1984 |publisher=[[Dumbarton Oaks]] |pages=65–93 |chapter=The First Christian Roman Emperor: Philip or Constantine? |chapter-url=https://archive.org/details/rome-and-the-arabs_202102/page/64}}</ref><ref>{{Cite journal |last=Pohlsander |first=Hans A. |date=1980 |title=Philip the Arab and Christianity |url=https://www.jstor.org/stable/4435734 |journal=Historia: Zeitschrift für Alte Geschichte |volume=29 |issue=4 |pages=463–473 |jstor=4435734 |issn=0018-2311}}</ref>}} He played a [[Constantine the Great and Christianity|pivotal role]] in elevating the status of Christianity in Rome, [[Edict of Milan|decriminalising Christian practice]] and ceasing [[Persecution of Christians in the Roman Empire|Christian persecution]]. This was a turning point in the [[Historiography of the Christianization of the Roman Empire|Christianisation of the Roman Empire]]. He founded the city of [[Constantinople]] (modern-day [[Istanbul]]) and made it the capital of the Empire, which it remained for over a millennium.

Born in Naissus, a city located in the [[Roman province|province]] of [[Moesia Superior]] (now [[Niš]], Serbia), Constantine was the son of [[Flavius Constantius]], a [[Roman army]] officer from Moesia Superior, who would become one of the four emperors of the [[Tetrarchy]]. His mother, [[Helena, mother of Constantine I|Helena]], was a woman of low birth, probably from [[Asia Minor]]. Later canonised as a [[saint]], she is credited for the conversion of her son in some traditions, though others believe that Constantine converted her. Constantine served with distinction under the Roman emperors [[Diocletian]] and [[Galerius]]. He began his career by campaigning in the eastern provinces against the [[Sasanian Empire|Persians]], before being recalled to the west in AD&nbsp;305 to fight alongside his father in the province of [[Roman Britain|Britannia]]. After his father's death in 306, Constantine was proclaimed as ''[[Augustus (title)|augustus]]'' (emperor) by his army at [[Eboracum]] ([[York]], England). He eventually emerged victorious in [[Civil wars of the Tetrarchy|the civil wars]] against the emperors [[Maxentius]] and [[Licinius]] to become the sole ruler of the [[Roman Empire]] by 324.

Upon his ascension, Constantine enacted numerous reforms to strengthen the empire. He restructured the government, separating civil and military authorities. To combat inflation, he introduced the [[Solidus (coin)|solidus]], a new gold coin that became the standard for Byzantine and European currencies for more than a thousand years. The [[Roman army]] was reorganised to consist of mobile units ({{lang|la|[[comitatenses]]}}), often around the emperor, to serve on campaigns against external enemies or Roman rebels, and frontier-garrison troops ({{lang|la|[[limitanei]]}}) which were capable of countering barbarian raids, but less and less capable, over time, of countering full-scale [[Migration Period|barbarian invasions]]. Constantine pursued [[German and Sarmatian campaigns of Constantine|successful campaigns]] against the tribes on the [[Roman military frontiers and fortifications|Roman frontiers]]—such as the [[Franks]], the [[Alemanni]], the [[Goths]], and the [[Sarmatians]]—and resettled territories abandoned by his predecessors during the [[Crisis of the Third Century]] with citizens of Roman culture.

Although Constantine lived much of his life as a [[pagan]] and later as a [[catechumen]], he began to favour Christianity beginning in 312, finally becoming a Christian and being baptised by [[Eusebius of Nicomedia]], an [[Arianism|Arian]] bishop, although the [[Catholic Church]] and the [[Coptic Orthodox Church]] maintain that he was baptised by [[Pope Sylvester I]]. He played an influential role in the proclamation of the [[Edict of Milan]] in 313, which declared [[Religion in ancient Rome#Christianity in the Roman Empire|tolerance for Christianity]] in the Roman Empire. He convoked the [[First Council of Nicaea]] in 325 which produced the statement of Christian belief known as the [[Nicene Creed]]. On his orders, the [[Church of the Holy Sepulchre]] was built at the site claimed to be the [[tomb of Jesus]] in [[Jerusalem]], and was deemed the holiest place in all of [[Christendom]]. The papal claim to [[Temporal power of the Holy See|temporal power]] in the [[High Middle Ages]] was based on the fabricated [[Donation of Constantine]]. He has historically been referred to as the "First Christian Emperor", but while he did favour the Christian Church, some modern scholars debate his beliefs and even his comprehension of Christianity.{{efn|Constantine was not baptised until just before his death.<ref>{{cite book |title=Constantinople: Capital of Byzantium |last=Harris |first=Jonathan |publisher=Bloomsbury |edition=2nd |year=2017 |url=https://books.google.com/books?id=b-ECDgAAQBAJ |page=38 |isbn=9781474254670}}</ref>}} Nevertheless, he is venerated as a saint in [[Eastern Christianity]], and he did much to push Christianity towards the mainstream of Roman culture.

The age of Constantine marked a distinct epoch in the history of the Roman Empire and a pivotal moment in the transition from [[classical antiquity]] to the [[Middle Ages]]. He built a new imperial residence in the city of [[Byzantium]], which was officially renamed ''[[New Rome]]'', while also taking on the name ''[[Constantinople]]'' in his honour. It subsequently served as the capital of the empire for more than a thousand years—with the Eastern Roman Empire for most of that period commonly referred to retrospectively as the ''[[Byzantine Empire]]'' in English. In leaving the empire to his sons and other members of the [[Constantinian dynasty]], Constantine's immediate political legacy was the effective replacement of Diocletian's Tetrarchy with the principle of [[Order of succession|dynastic succession]]. His memory was held in high regard during the lifetime of his children and for centuries after his reign. The medieval church held him up as a paragon of virtue, while secular rulers invoked him as a symbol of imperial legitimacy. The rediscovery of anti-Constantinian sources in the early [[Renaissance]] engendered more critical appraisals of his reign, with modern and contemporary scholarship often seeking to balance the extremes of earlier accounts.
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== Sources ==
Constantine was a ruler of major importance and has always been a controversial figure.{{sfn|Barnes|1981|p=272}} The fluctuations in his reputation reflect the nature of the ancient sources for his reign. These are abundant and detailed, but they have been strongly influenced by the official propaganda of the period and are often one-sided.{{sfnm|1a1=Lenski et al.|1pp=2–3, 14, 23–25|2a1=Southern|2y=2001|2p=169|3a1=Cameron|3y=2005|3pp=90–91}} No contemporaneous histories or biographies dealing with his life and rule have survived; the nearest alternative is [[Eusebius]]'s ''[[Life of Constantine|Vita Constantini]]'', which offers a mixture of [[eulogy]] and [[hagiography]]{{sfn|Barnes|1981|pp=265–68}} written between 335 and 339{{sfn|Drake|1988}} to extol Constantine's moral and religious virtues.<ref>Eusebius, ''Vita Constantini'' 1.11; cited in {{harvnb|Odahl|2001|p=3}}</ref> The ''Vita'' creates a contentiously positive image of Constantine,{{sfnm|1a1=Lenski et al.|1p=5|2a1=Storch|2y=1971}} and modern historians have frequently challenged its reliability.{{sfnm|1a1=Barnes|1y=1981|1pp=265–71|2a1=Cameron|2y=2005|2pp=90–92|3a1=Elliott|3y=1996|3pp=162–71}} The fullest secular life of Constantine is the anonymous ''[[Anonymus Valesianus|Origo Constantini]]'', a work of uncertain date which focuses on military and political events to the neglect of cultural and religious matters.{{sfnm|1a1=Lieu|1a2=Montserrat|1y=1996|1pp=39–40|2a1=Odahl|2y=2001|2p=3|3a1=Lenski et al.|3p=26}}

[[Lactantius]]' ''[[De mortibus persecutorum]]'', a political Christian pamphlet on the reigns of [[Diocletian]] and the [[Tetrarchy]], provides valuable but tendentious detail on Constantine's predecessors and early life.{{sfnm|1a1=Lenski et al.|1pp=14–32|2a1=Odahl|2y=2001|2pp=6–14}}{{sfnm|1a1=Barnes|1y=1981|1pp=12–14|2a1=MacKay|2y=1999|2p=207}} The [[ecclesiastical]] histories of [[Socrates of Constantinople|Socrates]], [[Sozomen]], and [[Theodoret]] describe the ecclesiastic disputes of Constantine's later reign. Written during the reign of [[Theodosius II]] (r. 402–450), a century after Constantine's reign, these ecclesiastical historians obscure the events and theologies of the Constantinian period through misdirection, misrepresentation, and deliberate obscurity.{{sfnm|1a1=Lenski et al.|1pp=14–32|2a1=Odahl|2y=2001|2pp=6–14}}{{sfnm|1a1=Barnes|1y=1981|1pp=12–14|2a1=MacKay|2y=1999|2p=207}}{{sfn|Barnes|1981|p=225}} The contemporary writings of the orthodox Christian [[Athanasius of Alexandria]] and the ecclesiastical history of the Arian [[Philostorgius]] also survive, though their biases are no less firm.{{sfn|Odahl|2001|pp=6, 10}}

The [[epitome]]s of [[Aurelius Victor]] (''De Caesaribus''), [[Eutropius (historian)|Eutropius]] (''Breviarium''), [[Festus (historian)|Festus]] (''Breviarium''), and the anonymous author of the ''[[Epitome de Caesaribus]]'' offer compressed secular political and military histories of the period. Although not Christian, the epitomes paint a favourable image of Constantine but omit reference to Constantine's religious policies.{{sfnm|1a1=Lenski et al.|1pp=14–32|2a1=Odahl|2y=2001|2pp=6–14}}{{sfnm|1a1=Lieu|1a2=Montserrat|1y=1996|1pp=2–6|2a1=Warmington|2y=1999|2pp=166–67}} The ''[[Panegyrici Latini]]'', a collection of [[panegyric]]s from the late 3rd and early 4th centuries, provides valuable information on the politics and ideology of the tetrarchic period and the early life of Constantine.{{sfnm|1a1=Lenski et al.|1pp=14–32|2a1=Odahl|2y=2001|2pp=6–14}}{{sfn|Wienand|2012|pp=26–86}} In addition, contemporary architecture—such as the [[Arch of Constantine]] in Rome and palaces in [[Gamzigrad]] and [[Córdoba, Spain|Córdoba]]{{sfnm|1a1=Lenski et al.|1pp=20–21, 288–91|2a1=Odahl|2y=2001|2pp=8–11}}—[[Epigraphy|epigraphic]] remains, and the [[coin]]age of the era complement the literary sources.{{sfnm|1a1=Lenski et al.|1pp=14–32|2a1=Odahl|2y=2001|2pp=6–14}}{{sfn|Wienand|2012|pp=26–86}}

== Early life ==
[[File:Медијана 02.jpg|thumb|upright=1.25|Remains of the luxurious residence palace of [[Mediana]], erected by Constantine I near his birth town of Naissus (now [[Niš]], Serbia)]]
Constantine was born on 27 February 272.{{sfn|Doležal|2022|pp=221-237}} While his official birthday is recorded in sources, his year of birth is not, and scholars have given several estimates between 271 and 280, with most leaning for 272 or 273. However, the evidence points to 272 being the correct year.{{sfn|Doležal|2022|pp=221-237}}{{efn|Constantine's age at the time of his death was 65 years and 3 months, as recorded by [[Eustathius of Epiphania|Eustathius]]. [[Socrates Scholasticus|Socrates]], [[Sozomen]], [[Joannes Zonaras|Zonaras]], [[Theodore Skoutariotes|Skoutariotes]], [[Theophanes the Confessor|Theophanes]], [[Symeon Logothete|Symeon]] and [[George Kedrenos|Kedrenos]] all record 65 years. [[Eutropius (historian)|Eutropius]] and [[Jerome]] ({{Circa}} 380) give 66 years, as Latin writers often used [[inclusive counting]]. [[Aurelius Victor]] gives 62, likely a corruption of {{Smallcaps|lxvi}} into {{Smallcaps|lxii}}, and his [[Epitome de Caesaribus|epitomer]] further corrupts the number into 63 ({{Smallcaps|lxiii}}), while also computing his regnal years wrong.{{sfn|Doležal|2022|pp=221-237}}{{sfn|Bernard|2019|p=543}}}} He was born inside the city of Naissus, during a time where the unity of the Empire was threatened by the breakaway wars of the [[Palmyrene Empire]]. The city (modern [[Niš]], Serbia) was located in [[Dardania (Roman province)|Dardania]] within the province of [[Moesia Superior]].{{sfnm|1a1=Barnes|1y=1981|1pp=3, 39–42|2a1=Elliott|2y=1996|2p=17|3a1=Odahl|3y=2001|3pp=15–16|4a1=Pohlsander|4y=2004b|5a1=Southern|5y=2001|5p=169, 341|6a1=Barnes|6y=1982|6pp=39–42|7a1=Jones|7y=1978|7pp=13–14|8a1=Lenski et al.|8p=59|9a1=Pohlsander|9y=2004a|9p=14|10a1=Rodgers|10y=1989|11a1=Wright|11y=1987}}<ref>{{cite encyclopedia|last=Wilkes|first=John|editor-last1=Hornblower|editor-first1=Simon|editor-last2=Spawforth|editor-first2=Antony|editor-last3=Eidinow|editor-first3=Esther|dictionary=The Oxford Classical Dictionary|date=2012|publisher=Oxford University Press|isbn=978-0-19-954556-8|entry-url=https://books.google.com/books?id=bVWcAQAAQBAJ&pg=PA414|entry=Dardani|page=414}}</ref> His father was [[Constantius Chlorus|Flavius Constantius]],{{efn|The claim that Constantius descended from [[Claudius Gothicus]], and thus also from the [[Flavian dynasty]], is most certainly a fabrication.{{sfn|Kazhdan|1991|pp=524–525}}{{sfn|Jones|Martindale|Morris|p=223}} His family probably adopted the name "Flavius" after being granted citizenship by one of the Flavian emperors, as it was common for "new Romans" to adopt the names of their benefactors.<ref>{{cite journal | last=Salway | year=1994 | first=Benet | title=What's in a Name? A Survey of Roman Onomastic Practice from c. 700 B.C. to A.D. 700 | journal=[[Journal of Roman Studies]] | volume=84 | pages=124–145 |doi=10.2307/300873 |jstor=300873 |s2cid=162435434 |url=https://discovery.ucl.ac.uk/id/eprint/114213/1/SalwayJRS1994.pdf |archive-url=https://web.archive.org/web/20200411100610/https://discovery.ucl.ac.uk/id/eprint/114213/1/SalwayJRS1994.pdf | archive-date=11 April 2020 | url-status=live | author-link=Benet Salway | issn=0075-4358 }}</ref>}} an [[Illyrians|Illyrian]].<ref name=Doležal>Stanislav Doležal, ''The Reign of Constantine, 306–337. Continuity and Change in the Late Roman Empire''. Palgrave Macmillan Cham, 2022; pp. 2–3: "In a sense, this book is dedicated to the "[[Illyrian Emperors]]", i.e. those emperors who were born in the Western Balkans and saved, stabilised, and reformed the empire. This line begins with Claudius II (268— 270) and then moves on to Quintillus (270), Aurelian (270—275), and Probus (276—282).3 After a brief interruption by the reigns of Carus and his two sons (282—284), whose birthplace we do not know, the Illyr-ians continued their run with Diocletian (284—305) and three of his colleagues: Maximian (285—305), Constantius (293—306), and Galerius (293—311). A 4th-century historian said of them: "Illyricum was actually the native land of all of them: so although they were deficient in culture, they had nevertheless been sufficiently schooled by the hardships of the countryside and of military service to be the best men for the state". 4 This is not the end of the Illyrian Emperors: Severus (305—307), Maximinus Daia (305—313), Licinius (308—324), and Constantine himself (306—337) can also be counted among them."</ref>{{sfn|Odahl|2004|pp=[https://books.google.com/books?id=770uCgAAQBAJ&pg=PA40 36-41]}}{{sfn|Kazhdan|1991|pp=524–525}}{{efn|name=Barnes2011p30|On the other hand, [[Timothy Barnes (classicist)|Timothy Barnes]] argues that when ancient writers used the words [[Illyria|Illyricum]] and [[Thrace]]/[[Thracians]] to describe where Constantius came from, they were speaking of broad geographic terms rather than precise origins.{{sfn|Barnes|2011|p=[https://books.google.com/books?id=MwIiAgAAQBAJ&pg=PA30 30]}}}} His original full name, as well as that of his father, is not known.<ref name=":1">{{Cite Pauly|IV,1|1013|1026|Constantius 1|[[Otto Seeck]]|RE:Constantius 1}}</ref><ref name=":2">{{Cite Pauly|IV,1|1013|1026|Constantinus 2|Conrad Benjamin|RE:Constantinus 2}}</ref> His ''[[praenomen]]'' is variously given as [[Lucius (praenomen)|Lucius]], [[Marcus (praenomen)|Marcus]] and [[Gaius (praenomen)|Gaius]].<ref name=":2" />{{efn|Constantius' regnal name is attested as both "Gaius Flavius Constantius" and "Marcus Flavius Constantius". However, the latter is almost certainly the correct form, as it was also the ''praenomen'' of his adopted father Maximian.{{sfn|Barnes|1982|p=5}}}} Whatever the case, ''praenomina'' had already disappeared from most public records by this time.<ref>{{Cite book |last=Wilson |first=Steven |url=https://books.google.com/books?id=YHeOAgAAQBAJ&pg=PA47 |title=The Means Of Naming: A Social History |publisher=[[Routledge]] |year=2003 |isbn=9781135368364 |pages=47}}</ref> He also adopted the name "Valerius", the ''[[Nomen gentilicium|nomen]]'' of emperor [[Diocletian]], following his father's ascension as [[Caesar (title)|caesar]].<ref name=":2" /><ref name=":1" />

Constantine probably spent little time with his father{{sfn|MacMullen|1969|p=21}} who was an officer in the Roman army, part of Emperor [[Aurelian]]'s imperial bodyguard. Being described as a tolerant and politically skilled man,<ref>''Panegyrici Latini'' 8(5), 9(4); Lactantius, ''De Mortibus Persecutorum'' 8.7; Eusebius, ''Vita Constantini'' 1.13.3</ref>{{sfn|Barnes|1981|pp=13, 290}} Constantius advanced through the ranks, earning the [[Roman governor|governorship]] of [[Dalmatia (Roman province)|Dalmatia]] from Emperor Diocletian, another of Aurelian's companions from [[Praetorian prefecture of Illyricum|Illyricum]], in 284 or 285.{{sfnm|1a1=Barnes|1y=1981|1p=3|2a1=Lenski et al.|2pp=59–60|3a1=Odahl|3y=2001|3pp=16–17}} Constantine's mother was [[Helena, mother of Constantine I|Helena]], a woman of low social standing, possibly from Drepanum (later renamed [[Helenopolis (Bithynia)|Helenopolis]]) of [[Bithynia]], which would likely have made her a Greek-speaker.<ref>{{Cite book |last=Hillner |first=Julia |url=https://books.google.com/books?id=6nWVEAAAQBAJ |title=Helena Augusta: Mother of the Empire |date=2023 |publisher=Oxford University Press |isbn=978-0-19-087529-9|p=20}}</ref><ref>{{Cite book |last=Drijvers |first=Jan Willem |url=https://books.google.com/books?id=AeV5DwAAQBAJ&pg=PA9 |title=Helena Augusta|date=1991 |publisher=BRILL |isbn=978-90-04-24676-8 |pages=9–17 }}</ref><ref>{{Cite book |last=Stanton |first=Andrea L. |url=https://books.google.com/books?id=GtCL2OYsH6wC&pg=PA25 |title=Cultural Sociology of the Middle East, Asia, and Africa: An Encyclopedia |date=2012 |publisher=SAGE |isbn=978-1-4129-8176-7 |pages=25 |language=en |quote="Constantine's mother, Helena, was a Greek from Asia Minor and also a devoted Christian who seemed to have influenced his choices."}}</ref> It is uncertain whether she was legally married to Constantius or merely his [[Concubinatus|concubine]].{{sfnm|1a1=Barnes|1y=1981|1pp=3, 39–42|2a1=Barnes|2y=1982|2p=39–40|3a1=Elliott|3y=1996|3p=17|4a1=Lenski et al.|4pp=59, 83|5a1=Odahl|5y=2001|5p=16|6a1=Pohlsander|6y=2004a|6p=14}} Constantine's own language was [[Latin]], and during his public speeches in the church councils, which were held in Greek, he needed Greek translators.<ref name=columbia>{{cite book |last1=Tejirian |first1=Eleanor H. |last2=Simon |first2=Reeva Spector |title=Conflict, conquest, and conversion: two thousand years of Christian missions in the Middle East |date=2012 |publisher=Columbia University Press |location=New York |isbn=978-0-231-51109-4 |page=15 |url=https://books.google.com/books?id=bHwMD0-X7aYC}}</ref>

{{multiple image
|caption_align=center
|image1=Istanbul - Museo archeol. - Diocleziano (284-305 d.C.) - Foto G. Dall'Orto 28-5-2006 (cropped).jpg
|width1=200
|caption1=Head from a statue of the emperor [[Diocletian]]
|image2=MSR - Tête de l'empreur Maximien Hercule - Inv 34 b (cropped).jpg
|width2=195
|caption2=Bust of [[Maximian]], Diocletian's co-emperor
}}
In April 286 Diocletian declared [[Maximian]], another colleague from Illyricum, his co-emperor. Each emperor would have his own court, his own military and administrative faculties, and each would rule with a separate [[praetorian prefect]] as chief lieutenant.{{sfnm|1a1=Barnes|1y=1981|1pp=8–14|2a1=Lenski et al.|2pp=46–50|3a1=Treadgold|3y=1997|3pp=14–15}} Maximian ruled in the West, from his capitals at ''[[Mediolanum]]'' ([[Milan]], Italy) or ''Augusta Treverorum'' ([[Trier]], Germany), while Diocletian ruled in the East, from [[Nicomedia]] ([[İzmit]], Turkey). The division was merely pragmatic: the empire was called "indivisible" in official panegyric, and both emperors could move freely throughout the empire.{{sfnm|1a1=Bowman|1y=2005|1p=70|2a1=Potter|2y=2004|2p=283|3a1a=Williams|3y=1997|3pp=49, 65}} In 288, Maximian appointed Constantius to serve as his praetorian prefect in [[Roman Gaul|Gaul]]. Constantius left Helena to marry Maximian's stepdaughter [[Flavia Maximiana Theodora|Theodora]] in 288 or 289.{{sfnm|1a1=Barnes|1y=1981|1p=3|2a1=Elliott|2y=1996|2p=20|3a1=Lenski et al.|3pp=59–60|4a1=Odahl|4y=2001|4pp=47, 299|5a1=Pohlsander|5y=2004a|5p=14}}

Diocletian divided the empire again in 293, appointing two caesars to rule over further subdivisions of East and West. Each would be subordinate to his respective ''augustus'' but would act with supreme authority in his assigned lands. This system would later be called the Tetrarchy. Diocletian's first appointee for the office of Caesar was [[Constantius Chlorus|Constantius]]; his second was [[Galerius]], a native of [[Gamzigrad|''Felix Romuliana'']]. According to [[Lactantius]], Galerius was a brutal, animalistic man. Although he shared the paganism of Rome's aristocracy, he seemed to them an alien figure, a semi-barbarian.<ref>Lactantius, ''De Mortibus Persecutorum'' 7.1; cited in {{harvnb|Barnes|1981|pp=13, 290}}</ref> On 1 March, Constantius was promoted to the office of ''Caesar'', and dispatched to Gaul to fight the rebels [[Carausius]] and [[Allectus]]. In spite of [[Meritocracy|meritocratic]] overtones, the Tetrarchy retained vestiges of hereditary privilege, and Constantine became the prime candidate for future appointment as Caesar as soon as his father took the position. Constantine went to the court of Diocletian, where he lived as his father's [[heir presumptive]].{{sfnm|1a1=Barnes|1y=1981|1pp=3, 8–9|2a1=Lenski et al.|2pp= 40–43, 54|3a1=Elliott|3y=1996|3p=20|4a1=Odahl|4y=2001|4pp=46–47, 56–57|5a1=Pohlsander|5y=2004a|5pp=8–9, 14|6a1=Treadgold|6y=1997|6p=17}}

=== In the East ===
Constantine received a formal education at Diocletian's court, where he learned Latin literature, Greek, and philosophy.{{sfnm|1a1=Barnes|1y=1981|1p=73–74|2a1=Lenski et al.|2pp=60|3a1=Odahl|3y=2001|3pp=72, 301}} The cultural environment in Nicomedia was open, fluid, and socially mobile; in it, Constantine could mix with intellectuals both pagan and Christian. He may have attended the lectures of Lactantius, a Christian scholar of Latin in the city.{{sfnm|1a1=Barnes|1y=1981|1p=73–74|2a1=Fowden|2y=1988|2pp=175–76}} Because Diocletian did not completely trust Constantius—none of the Tetrarchs fully trusted their colleagues—Constantine was held as something of a hostage, a tool to ensure Constantius' best behavior. Constantine was nonetheless a prominent member of the court: he fought for Diocletian and Galerius in Asia and served in a variety of [[tribune|tribunates]]; he campaigned against barbarians on the [[Danube]] in 296 and fought the Persians under Diocletian in Syria in 297, as well as under Galerius in [[Mesopotamia]] in 298–299.<ref>Constantine, ''Oratio ad Sanctorum Coetum'', 16.2</ref>{{sfnm|1a1=Elliott|1y=1996|1pp=29–30|2a1=Lenski et al.|2p=60|3a1=Odahl|3y=2001|3pp=72–74}} By late 305, according to some, he had become a tribune of the first order, a ''tribunus ordinis primi''.{{sfnm|1a1=Elliott|1y=1996|1pp=29–30|2a1=Lenski et al.|2p=60|3a1=Odahl|3y=2001|3pp=72–74}}{{sfn|Pohlsander|2004a|p=15}}

[[File:Romuliana Galerius head.jpg|thumb|left|[[Porphyry (geology)|Porphyry]] bust of Emperor Galerius]]
Constantine had returned to Nicomedia from the eastern front by the spring of 303, in time to witness the beginnings of Diocletian's "[[Diocletianic Persecution|Great Persecution]]", the most severe [[Persecution of Christians in the Roman Empire|persecution of Christians]] in Roman history.<ref>Constantine, ''Oratio ad Sanctorum Coetum'' 25</ref>{{sfnm|1a1=Elliott|1y=1996|1p=30|2a1=Odahl|2y=2001|2p=73}} In late 302, Diocletian and Galerius sent a messenger to the [[oracle]] of [[Apollo]] at [[Didyma]] with an inquiry about Christians.<ref>Lactantius, ''De Mortibus Persecutorum'' 10.6–11</ref>{{sfnm|1a1=Barnes|1y=1981|1p=21|2a1=Elliott|2y=1996|2pp=35–36|3a1=MacMullen|3y=1969|3p=24|4a1=Odahl|4y=2001|4p=67|5a1=Potter|5y=2004|5p=338}} Constantine could recall his presence at the palace when the messenger returned and Diocletian accepted the imperial court's demands for universal persecution.<ref>Eusebius, ''Vita Constantini'' 2.49–52</ref>{{sfnm|1a1=Barnes|1y=1981|1p=21|2a1=Odahl|2y=2001|2pp=67, 73, 304|3a1=Potter|3y=2004|3p=338}} On 23 February 303, Diocletian ordered the destruction of Nicomedia s new church, condemned its scriptures to the flames, and had its treasures seized. In the months that followed, churches and scriptures were destroyed, Christians were deprived of official ranks, and priests were imprisoned.{{sfnm|1a1=Barnes|1y=1981|1pp=22–25|2a1=MacMullen|2y=1969|2pp=24–30|3a1=Odahl|3y=2001|3pp=67–69|4a1=Potter|4y=2004|4p=337}} It is unlikely that Constantine played any role in the persecution.{{sfn|MacMullen|1969|pp=24–25}} In his later writings, he attempted to present himself as an opponent of Diocletian's "sanguinary edicts" against the "Worshippers of God",<ref>''Oratio ad Sanctorum Coetum'' 25</ref>{{sfn|Odahl|2001|p=73}} but nothing indicates that he opposed it effectively at the time. Although no contemporary Christian challenged Constantine for his inaction during the persecutions, it remained a political liability throughout his life.{{sfnm|1a1=Elliott|1y=1987|1pp=425–26|2a1=Lenski et al.|2p=126}}

On 1 May 305 Diocletian, as a result of a debilitating sickness taken in the winter of 304–305, announced his resignation. In a parallel ceremony in [[Milan]], Maximian did the same.{{sfnm|1a1=Barnes |1y=1981 |1pp=25–27 |2a1=Lenski et al. |2p=60 |3a1=Odahl |3y=2001 |3pp=69–72 |4a1=Pohlsander |4y=2004a |4p=15 |5a1=Potter |5y=2004 |5pp=341–342}} Lactantius states that Galerius manipulated the weakened Diocletian into resigning and forced him to accept Galerius' allies in the imperial succession. According to Lactantius, the crowd listening to Diocletian's resignation speech believed, until the last moment, that Diocletian would choose Constantine and Maxentius (Maximian's son) as his successors.<ref>Lactantius, ''De Mortibus Persecutorum'' 19.2–6</ref>{{sfnm|1a1=Barnes |1y=1981 |1p=26 |2a1=Potter |2y=2004 |2p=342}} It was not to be: Constantius and Galerius were promoted to ''augusti'', while [[Severus II|Severus]] and [[Maximinus Daza|Maximinus]], Galerius' nephew, were appointed their caesars respectively. Constantine and Maxentius were ignored.{{sfnm|1a1=Lenski et al. |1pp=60–61 |2a1=Odahl |2y=2001 |2pp=72–74 |3a1=Pohlsander |3y=2004a |3p=15}}

Some of the ancient sources detail plots that Galerius made on Constantine's life in the months following Diocletian's abdication. They assert that Galerius assigned Constantine to lead an advance unit in a cavalry charge through a swamp on the middle Danube, made him enter into single combat with a lion, and attempted to kill him in hunts and wars. Constantine always emerged victorious: the lion emerged from the contest in a poorer condition than Constantine; Constantine returned to Nicomedia from the Danube with a Sarmatian captive to drop at Galerius' feet.<ref>''Origo'' 4; Lactantius, ''De Mortibus Persecutorum'' 24.3–9; Praxagoras fr. 1.2; Aurelius Victor 40.2–3; ''Epitome de Caesaribus'' 41.2; Zosimus 2.8.3; Eusebius, ''Vita Constantini'' 1.21</ref>{{sfnm|1a1=Lenski et al. |1p=61 |2a1=MacMullen |2y=1969 |2p=32 |3a1=Odahl |3y=2001 |3p=73 }} It is uncertain how much these tales can be trusted.{{sfn|Lenski et al.|p=61}}

=== In the West ===
Constantine recognised the implicit danger in remaining at Galerius' court, where he was held as a virtual hostage. His career depended on being rescued by his father in the West. Constantius was quick to intervene. In the late spring or early summer of 305, Constantius requested leave for his son to help him campaign in Britain. After a long evening of drinking, Galerius granted the request. Constantine's later propaganda describes how he fled the court in the night, before Galerius could change his mind. He rode from [[Cursus publicus|post-house]] to post-house at high speed, [[hamstringing]] every horse in his wake. By the time Galerius awoke the following morning, Constantine had fled too far to be caught. Constantine joined his father in [[Roman Gaul|Gaul]], at ''Bononia'' ([[Boulogne-sur-Mer|Boulogne]]) before the summer of 305.{{sfnm|1a1=Barnes |1y=1981 |1p=27 |2a1=Elliott |2y=1987 |2pp=39–40 |3a1=Lenski et al.|3p=61 |4a1=Odahl |4y=2001 |4p=75–77|5a1=Pohlsander |5y=2004a |5pp=15–16|6a1=Potter |6y=2004 |6pp=344–45 |7a1=Southern |7y=2001 |7pp=169–70, 341 |8a1=MacMullen |8y=1969 |8p=32}}

[[File:Statue Constantin 1er York 13.jpg|thumb|[[Statue of Constantine the Great, York|Modern bronze statue of Constantine I in York]], England, near the spot where he was proclaimed [[Augustus (title)|Augustus]] in 306]]
From Bononia they crossed the [[English Channel]] to Britain and made their way to Eboracum ([[York]]), capital of the province of [[Britannia Secunda]] and home to a large military base. Constantine was able to spend a year in northern Britain at his father's side, campaigning against the [[Picts]] beyond [[Hadrian's Wall]] in the summer and autumn.{{sfnm|1a1=Barnes |1y=1981 |1pp=27, 298 |2a1=Elliott |2y=1996 |2p=39 |3a1=Odahl |3y=2001 |3p=77–78, 309 |4a1=Pohlsander |4y=2004a |4pp=15–16}} Constantius' campaign, like that of [[Septimius Severus]] before it, probably advanced far into the north without achieving great success.{{sfnm|1a1=Alföldi|1y=1948|1pp=233–34|2a1=Southern|2y=2001|2pp=170, 341}} Constantius had become severely sick over the course of his reign and died on 25 July 306 in Eboracum. Before dying, he declared his support for raising Constantine as emperor. The [[Alamanni]]c king [[Chrocus]], a barbarian taken into service under Constantius, then proclaimed Constantine as augustus. The troops loyal to Constantius' memory followed him in acclamation. Gaul and Britain quickly accepted his rule;{{sfnm|1a1=Barnes |1y=1981 |1pp=27–29 |2a1=Jones |2y=1978 |2p=59 |3a1=Lenski et al. |3pp=61–62 |4a1=Odahl |4y=2001 |4pp=78–80}} [[Hispania]], which had been in his father's domain for less than a year, rejected it.{{sfn|Jones|1978|p=59}}

Constantine sent Galerius an official notice of Constantius' death and his own acclamation. Along with the notice, he included a portrait of himself in the robes of an Augustus.{{sfnm|1a1=Barnes |1y=1981 |1pp=27–29 |2a1=Jones |2y=1978 |2p=59 |3a1=Lenski et al. |3pp=61–62 |4a1=Odahl |4y=2001 |4pp=78–80}} The portrait was wreathed in [[Laurus nobilis|bay]].{{sfnm|1a1=Jones|1y=1978|1p=59|2a1=MacMullen |2y=1969 |2p=39}} He requested recognition as heir to his father's throne and passed off responsibility for his unlawful ascension on his army, claiming they had "forced it upon him".{{sfn|Treadgold|1997|p=28}} Galerius was put into a fury by the message; he almost set the portrait and messenger on fire.<ref>{{Cite book |last=Gibbon, Edward |title=History of The Decline and Fall of The Roman Empire. |date=2018 |publisher=[Otbebookpublishing] |isbn=978-3-96272-518-1 |oclc=1059411020}}</ref> His advisers calmed him and argued that outright denial of Constantine's claims would mean certain war.{{sfnm|1a1=Barnes |1y=1981 |1pp=28–29 |2a1=Rees |2y=2002 |2p=160 |3a1=Lenski et al. |3p=62 |4a1=Odahl |4y=2001 |4pp=78–80}} Galerius was compelled to compromise: he granted Constantine the title "caesar" rather than "augustus" (the latter office went to Severus instead). Wishing to make it clear that he alone gave Constantine legitimacy, Galerius personally sent Constantine the emperor's traditional [[Tyrian purple|purple robes]]. Constantine accepted the decision, knowing that it would remove doubts as to his legitimacy.{{sfnm|1a1=Barnes |1y=1981 |1p=29 |2a1=Elliott |2y=1996 |2p=41 |3a1=Jones |3y=1978 |3p=41 |4a1=MacMullen |4y=1969 |4p=39 |5a1=Odahl |5y=2001 |5pp=79–80}}

== Reign ==
[[File:Constantine I RIC VI 824 (obverse).jpeg|thumb|left|upright|[[Aureus]] of Constantine; the inscription around the portrait is "Constantinus P[ius] F[elix] Aug[ustus]"]]

Constantine's share of the empire consisted of Britain, Gaul, and Spain, and he commanded one of the largest Roman armies which was stationed along the important [[Rhine]] frontier.<ref>Pohlsander, ''Emperor Constantine'', 16–17.</ref> He remained in Britain after his promotion to emperor, driving back the tribes of the Picts and securing his control in the northwestern dioceses. He completed the reconstruction of military bases begun under his father's rule, and he ordered the repair of the region's roadways.<ref>Odahl, 80–81.</ref> He then left for [[History of Trier|''Augusta Treverorum'']] ([[Trier]]) in Gaul, the Tetrarchic capital of the northwestern Roman Empire.<ref>Odahl, 81.</ref> The Franks learned of Constantine's acclamation and invaded Gaul across the lower Rhine over the winter of 306–307.<ref>MacMullen, ''Constantine'', 39; Odahl, 81–82.</ref> He drove them back beyond the Rhine and captured kings [[Ascaric]] and [[Merogais]]; the kings and their soldiers were fed to the beasts of [[Trier Amphitheater]] in the ''[[Adventus (ceremony)|adventus]]'' (arrival) celebrations which followed.<ref>Barnes, ''Constantine and Eusebius'', 29; Elliott, ''Christianity of Constantine'', 41; Lenski, "Reign of Constantine" (CC), 63; MacMullen, ''Constantine'', 39–40; Odahl, 81–83.</ref>

[[File:Trier Kaiserthermen BW 1.JPG|thumb|Public baths (''[[thermae]]''; [[Trier Imperial Baths]]) built in [[Trier]] by Constantine, more than {{convert|100|m|0}} wide by {{convert|200|m|0}} long and capable of serving several thousand at a time, built to rival those of Rome<ref>Odahl, 82–83.</ref>]]
[[File:San Giovanni in Laterano - 2019 - Statue of Constantius II 03.jpg|thumb|Original upper part of a statue of either Constantine or his son [[Constantine II (emperor)|Constantine II]], which probably decorated the [[Baths of Constantine (Rome)|Baths of Constantine in Rome]]<ref>[http://laststatues.classics.ox.ac.uk/database/detail.php?record=LSA-556 http://laststatues.classics.ox.ac.uk, LSA-556 (Heintze, H.)]</ref>]]
Constantine began a major expansion of Trier. He strengthened the circuit wall around the city with military towers and fortified gates, and he began building a palace complex in the northeastern part of the city. To the south of his palace, he ordered the construction of a large formal audience hall and a massive imperial bathhouse. He sponsored many building projects throughout Gaul during his tenure as emperor of the West, especially in Augustodunum ([[Autun]]) and Arelate ([[Arles]]).<ref>Odahl, 82–83. See also: William E. Gwatkin, Jr. [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/journals/CJ/29/1/Roman_Trier*.html Roman Trier]." ''The Classical Journal'' 29 (1933): 3–12.</ref> According to Lactantius, Constantine followed a tolerant policy towards Christianity, although he was not yet a Christian. He probably judged it a more sensible policy than open persecution<ref>Lactantius, ''De Mortibus Persecutorum'' 24.9; Barnes, "Lactantius and Constantine", 43–46; Odahl, 85, 310–11.</ref> and a way to distinguish himself from the "great persecutor" Galerius.<ref>Odahl, 86.</ref> He decreed a formal end to persecution and returned to Christians all that they had lost under the first of the persecuting edicts.<ref>Barnes, ''Constantine and Eusebius'', 28.</ref>

Constantine was largely untried and had a hint of illegitimacy about him; he relied on his father's reputation in his early propaganda, which gave as much coverage to his father's deeds as to his.<ref>Rodgers, 236.</ref> His military skill and building projects, however, soon gave the panegyrist the opportunity to comment favourably on the similarities between father and son, and Eusebius remarked that Constantine was a "renewal, as it were, in his own person, of his father's life and reign".<ref>''Panegyrici Latini'' 7(6)3.4; Eusebius, ''Vita Constantini'' 1.22, qtd. and tr. Odahl, 83; Rodgers, 238.</ref> Constantinian coinage, sculpture, and oratory also show a tendency for disdain towards the "barbarians" beyond the frontiers. He minted a coin issue after his victory over the Alemanni which depicts weeping and begging Alemannic tribesmen, "the Alemanni conquered" beneath the phrase "Romans' rejoicing".<ref>MacMullen, ''Constantine'', 40.</ref> There was little sympathy for these enemies; as his panegyrist declared, "It is a stupid clemency that spares the conquered foe."<ref>Qtd. in MacMullen, ''Constantine'', 40.</ref>

=== Maxentius's rebellion ===
[[File:Portrait of Maxentius (SK Dresden Hm 406) 05.jpg|thumb|left|upright|Dresden bust of Emperor [[Maxentius]], who was defeated by Constantine at the [[Battle of the Milvian Bridge]]]]

Following Galerius's recognition of Constantine as caesar, Constantine's portrait was brought to Rome, as was customary. Maxentius mocked the portrait's subject as the son of a harlot and lamented his own powerlessness.<ref>Zosimus, 2.9.2; Lenski, "Reign of Constantine" (CC), 62; MacMullen, ''Constantine'', 39.</ref> Maxentius, envious of Constantine's authority,<ref>Barnes, ''Constantine and Eusebius'', 29; Odahl, 86; Potter, 346.</ref> seized the title of emperor on 28 October 306. Galerius refused to recognise him but failed to unseat him. Severus was sent against Maxentius in April 307,<ref>Barnes, ''New Empire'', 5. Galerius and Maximinus ceased to be recognized as consuls at this time.</ref> but during the campaign, Severus' armies, previously under command of Maxentius' father Maximian, defected, and Severus was seized and imprisoned.<ref>Barnes, ''Constantine and Eusebius'', 30–31; Elliott, ''Christianity of Constantine'', 41–42; Lenski, "Reign of Constantine" (CC), 62–63; Odahl, 86–87; Potter, 348–49.</ref> Maximian, brought out of retirement by his son's rebellion, left for Gaul to confer with Constantine. He offered to marry his daughter [[Fausta]] to Constantine and elevate him to augustan rank. In return, Constantine would reaffirm the old family alliance between Maximian and Constantius and offer support to Maxentius' cause in Italy. Constantine accepted and married Fausta in Trier in summer 307.{{efn|The event is the focus of the ''[[Panegyrici Latini]]'' VI. The exact chronology of events is uncertain. Constantine and Fausta's wedding is sometimes dated to 31 March, but this is probably a mistake. It probably took place in September 307.<ref>{{Cite book |last1=Nixon |first1=C. E. V. |url=https://books.google.com/books?id=Vu3QEAAAQBAJ |title=In Praise of Later Roman Emperors: The Panegyrici Latini |last2=Rodgers |first2=Barbara S. |date=2023 |publisher=University of California Press |isbn=978-0-520-34282-8 |pages=180–185}} The ceremony took place after 25 July, as there are coins that refer to Constantine as ''caesar'' while also commemorating his ''[[dies imperii]]''.</ref>{{sfn|Rees|2002|p=[https://books.google.com/books?id=LQQ5Ce-2de4C&pg=PA165 165]}}<ref>{{Cite book |last=Sang |first=J.C. |url=https://open.uct.ac.za/server/api/core/bitstreams/842aeb2d-7a99-434e-8f92-3e31acdd39f5/content |title=Panegyrici Latini, VI and VII: Translated with Introductions and Commentary |date=1979 |publisher=University of Cape Town |isbn=978-0-19-924918-3 |pages=6–14, favouring late April/early May instead}}</ref>}} Constantine gave Maxentius his meagre support, offering Maxentius political recognition.<ref>Barnes, ''Constantine and Eusebius'', 31; Lenski, "Reign of Constantine" (CC), 64; Odahl, 87–88; Pohlsander, ''Emperor Constantine'', 15–16.</ref>

Constantine remained aloof from the Italian conflict, however. Over the spring and summer of 307 he had left Gaul for Britain to avoid any involvement in the Italian turmoil;<ref>Barnes, ''Constantine and Eusebius'', 30; Lenski, "Reign of Constantine" (CC), 62–63; Odahl, 86–87.</ref> now, instead of giving Maxentius military aid, he sent his troops against Germanic tribes along the Rhine. In 308, he raided the territory of the [[Bructeri]] and made a bridge across the Rhine at Colonia Agrippinensium ([[Cologne]]). In 310, he marched to the northern Rhine and fought the Franks. When not campaigning, he toured his lands advertising his benevolence and supporting the economy and the arts. His refusal to participate in the war increased his popularity among his people and strengthened his power base in the West.<ref>Barnes, ''Constantine and Eusebius'', 34; Lenski, "Reign of Constantine" (CC), 63–65; Odahl, 89; Pohlsander, ''Emperor Constantine'', 15–16.</ref> Maximian returned to Rome in the winter of 307–308 but soon fell out with his son. In early 308, after a failed attempt to usurp Maxentius' title, Maximian returned to Constantine's court.<ref>Barnes, ''Constantine and Eusebius'', 32; Lenski, "Reign of Constantine" (CC), 64; Odahl, 89, 93.</ref>

On 11 November 308 Galerius called a general council at the military city of [[Carnuntum]] ([[Petronell-Carnuntum]], Austria) to resolve the instability in the western provinces. In attendance were Diocletian, briefly returned from retirement, Galerius, and Maximian. Maximian was forced to abdicate again and Constantine was again demoted to caesar. [[Licinius]], one of Galerius' old military companions, was appointed augustus in the western regions. The new system did not last long: Constantine refused to accept the demotion and continued to style himself as augustus on his coinage, even as other members of the Tetrarchy referred to him as a caesar on theirs. [[Maximinus Daza|Maximinus]] was frustrated that he had been passed over for promotion while the newcomer Licinius had been raised to the office of augustus and demanded that Galerius promote him. Galerius offered to call both Maximinus and Constantine "sons of the augusti",<ref>Barnes, ''Constantine and Eusebius'', 32–34; Elliott, ''Christianity of Constantine'', 42–43; Jones, 61; Lenski, "Reign of Constantine" (CC), 65; Odahl, 90–91; Pohlsander, ''Emperor Constantine'', 17; Potter, 349–50; Treadgold, 29.</ref> but neither accepted the new title. By the spring of 310, Galerius was referring to both men as augusti.<ref>Barnes, ''Constantine and Eusebius'', 33; Jones, 61.</ref>

=== Maximian's rebellion ===
[[File:Constantin 1er multiple d'or 39,79 g.jpg|thumb|upright=1.2|A gold [[solidus (coin)|solidus]] of "Unconquered Constantine" with the god [[Sol Invictus]] behind him, struck in AD&nbsp;313. The use of Sol's image stressed Constantine's status as his father's successor, appealed to the educated citizens of Gaul, and was considered less offensive than the traditional pagan pantheon to the Christians.<ref>Barnes, ''Constantine and Eusebius'', 36–37.</ref>]]

In 310 a dispossessed Maximian rebelled against Constantine while Constantine was away campaigning against the Franks. Maximian had been sent south to Arles with a contingent of Constantine's army, in preparation for any attacks by Maxentius in southern Gaul. He announced that Constantine was dead and took up the imperial purple. In spite of a large donative pledge to any who would support him as emperor, most of Constantine's army remained loyal to their emperor, and Maximian was soon compelled to leave. When Constantine heard of the rebellion, he abandoned his campaign against the Franks and marched his army up the Rhine.<ref name="yuhknp">Barnes, ''Constantine and Eusebius'', 34–35; Elliott, ''Christianity of Constantine'', 43; Lenski, "Reign of Constantine" (CC), 65–66; Odahl, 93; Pohlsander, ''Emperor Constantine'', 17; Potter, 352.</ref> At Cabillunum ([[Chalon-sur-Saône]]), he moved his troops onto waiting boats to row down the slow waters of the [[Saône]] to the quicker waters of the [[Rhône|Rhone]]. He disembarked at [[Lugdunum]] ([[Lyon]]).<ref>Barnes, ''Constantine and Eusebius'', 34.</ref> Maximian fled to Massilia ([[Marseille]]), a town better able to withstand a long siege than Arles. It made little difference, however, as loyal citizens opened the rear gates to Constantine. Maximian was captured and reproved for his crimes. Constantine granted some clemency but strongly encouraged his suicide. In July 310, Maximian [[Suicide by hanging|hanged himself]].<ref name="yuhknp" />

In spite of the earlier rupture in their relations, Maxentius was eager to present himself as his father's devoted son after his death.<ref>Elliott, ''Christianity of Constantine'', 43; Lenski, "Reign of Constantine" (CC), 68; Pohlsander, ''Emperor Constantine'', 20.</ref> He began minting coins with his father's deified image, proclaiming his desire to avenge Maximian's death.<ref>Elliott, ''Christianity of Constantine'', 45; Lenski, "Reign of Constantine" (CC), 68.</ref> Constantine initially presented the suicide as an unfortunate family tragedy. By 311, however, he was spreading another version. According to this, after Constantine had pardoned him, Maximian planned to murder Constantine in his sleep. Fausta learned of the plot and warned Constantine, who put a [[eunuch]] in his own place in bed. Maximian was apprehended when he killed the eunuch and was offered suicide, which he accepted.<ref>Lactantius, ''De Mortibus Persecutorum'' 30.1; Barnes, ''Constantine and Eusebius'', 40–41, 305.</ref> Along with using propaganda, Constantine instituted a ''[[damnatio memoriae]]'' on Maximian, destroying all inscriptions referring to him and eliminating any public work bearing his image.<ref>Barnes, ''Constantine and Eusebius'', 41; Lenski, "Reign of Constantine" (CC), 68.</ref>

The death of Maximian required a shift in Constantine's public image. He could no longer rely on his connection to the elder Emperor Maximian and needed a new source of legitimacy.<ref>Potter, 352.</ref> In a speech delivered in Gaul on 25 July 310, the anonymous orator reveals a previously unknown dynastic connection to [[Claudius Gothicus|Claudius II]], a 3rd-century emperor famed for defeating the [[Goths]] and restoring order to the empire. Breaking away from tetrarchic models, the speech emphasises Constantine's ancestral [[prerogative]] to rule, rather than principles of imperial equality. The new ideology expressed in the speech made Galerius and Maximian irrelevant to Constantine's right to rule.<ref>''Panegyrici Latini'' 6(7); Barnes, ''Constantine and Eusebius'', 35–37, 301; Lenski, "Reign of Constantine" (CC), 66; Odahl, 94–95, 314–15; Potter, 352–53.</ref> Indeed, the orator emphasises ancestry to the exclusion of all other factors: "No chance agreement of men, nor some unexpected consequence of favour, made you emperor," the orator declares to Constantine.<ref>''Panegyrici Latini'' 6(7)1. Qtd. in Potter, 353.</ref>

The oration also moves away from the religious ideology of the Tetrarchy, with its focus on twin dynasties of [[Jupiter (mythology)|Jupiter]] and [[Hercules]]. Instead, the orator proclaims that Constantine experienced a divine vision of [[Apollo]] and [[Victoria (mythology)|Victory]] granting him [[laurel wreath]]s of health and a long reign. In the likeness of Apollo, Constantine recognised himself as the saving figure to whom would be granted "rule of the whole world",<ref>''Panegyrici Latini'' 6(7).21.5.</ref> as the poet [[Virgil]] had once foretold.<ref>Virgil, ''[[Bucolics|Ecologues]]'' 4.10.</ref> The oration's religious shift is paralleled by a similar shift in Constantine's coinage. In his early reign, the coinage of Constantine advertised [[Mars (mythology)|Mars]] as his patron. From 310 on, Mars was replaced by [[Sol Invictus]], a god conventionally identified with Apollo.<ref>Barnes, ''Constantine and Eusebius'', 36–37; Lenski, "Reign of Constantine" (CC), 67; Odahl, 95.</ref> There is little reason to believe that either the dynastic connection or the divine vision are anything other than fiction, but their proclamation strengthened Constantine's claims to legitimacy and increased his popularity among the citizens of Gaul.<ref>Barnes, ''Constantine and Eusebius'', 36–37; Elliott, ''Christianity of Constantine'', 50–53; Lenski, "Reign of Constantine" (CC), 66–67; Odahl, 94–95.</ref>

=== Civil wars ===
{{See also|Civil wars of the Tetrarchy}}

==== War against Maxentius ====
{{Campaignbox Constantine Wars}}
By the middle of 310 Galerius had become too ill to involve himself in imperial politics.<ref>Lactantius, ''De Mortibus Persecutorum'' 31–35; Eusebius, ''Historia Ecclesiastica'' 8.16; Elliott, ''Christianity of Constantine'', 43; Lenski, "Reign of Constantine" (CC), 68; Odahl, 95–96, 316.</ref> His final act survives: a letter to provincials posted in ''Nicomedia'' on 30 April 311, proclaiming an end to the persecutions, and the resumption of religious toleration.<ref>Lactantius, ''De Mortibus Persecutorum'' 34; Eusebius, ''Historia Ecclesiastica'' 8.17; Barnes, ''Constantine and Eusebius'', 304; Jones, 66.</ref>

Eusebius maintains "divine providence [...] took action against the perpetrator of these crimes" and gives a graphic account of Galerius' demise:

"Without warning suppurative inflammation broke out round the middle of his genitals, then a deep-seated fistula ulcer; these ate their way incurably into his innermost bowels. From them came a teeming indescribable mass of worms, and a sickening smell was given off, for the whole of his hulking body, thanks to over eating, had been transformed even before his illness into a huge lump of flabby fat, which then decomposed and presented those who came near it with a revolting and horrifying sight."<ref>{{Cite book |last=Eusebius |title=The History of the Church |publisher=Penguin Classics |year=1965 |isbn=0140445358 |pages=278}}</ref>

Galerius died soon after the edict's proclamation,<ref>Barnes, ''Constantine and Eusebius'', 39; Elliott, ''Christianity of Constantine'', 43–44; Lenski, "Reign of Constantine" (CC), 68; Odahl, 95–96.</ref> destroying what little remained of the Tetrarchy.<ref>Barnes, ''Constantine and Eusebius'', 41; Elliott, ''Christianity of Constantine'', 45; Lenski, "Reign of Constantine" (CC), 69; Odahl, 96.</ref> Maximinus mobilised against Licinius and seized [[Anatolia|Asia Minor]]. A hasty peace was signed on a boat in the middle of the [[Bosporus|Bosphorus]].<ref>Barnes, ''Constantine and Eusebius'', 39–40; Elliott, ''Christianity of Constantine'', 44; Odahl, 96.</ref> While Constantine toured Britain and Gaul, Maxentius prepared for war.<ref>Odahl, 96.</ref> He fortified northern Italy and strengthened his support in the Christian community by allowing it to elect [[Pope Eusebius|Eusebius]] as [[diocese of Rome|bishop of Rome]].<ref>Barnes, ''Constantine and Eusebius'', 38; Odahl, 96.</ref>[[File:Dame-Schmuckkasten-Trier.jpg|thumb|left|A Roman fresco in [[Trier]], Germany, possibly depicting [[Flavia Julia Constantia|Constantia]]<ref>{{Cite book |last=Hillner |first=Julia |date=2017 |title=Constantia |chapter=Constantia, half-sister of Constantine and wife of Licinius |url=https://oxfordre.com/display/10.1093/acrefore/9780199381135.001.0001/acrefore-9780199381135-e-8065 |series=Oxford Research Encyclopedia of Classics |doi=10.1093/acrefore/9780199381135.013.8065 |isbn=978-0-19-938113-5}}</ref>]]
Maxentius' rule was nevertheless insecure. His early support dissolved in the wake of heightened tax rates and depressed trade; riots broke out in Rome and [[Carthage]];<ref>Barnes, ''Constantine and Eusebius'', 37; Curran, 66; Lenski, "Reign of Constantine" (CC), 68; MacMullen, ''Constantine'', 62.</ref> and [[Domitius Alexander]] was able to briefly usurp his authority in Africa.<ref name="leohak">Barnes, ''Constantine and Eusebius'', 37.</ref> By 312, he was a man barely tolerated, not one actively supported,<ref>Barnes, ''Constantine and Eusebius'', 37–39.</ref> even among Christian Italians.<ref>Barnes, ''Constantine and Eusebius'', 38–39; MacMullen, ''Constantine'', 62.</ref> In the summer of 311, Maxentius mobilised against Constantine while Licinius was occupied with affairs in the East. He declared war on Constantine, vowing to avenge his father's "murder".<ref>Barnes, ''Constantine and Eusebius'', 40; Curran, 66.</ref> To prevent Maxentius from forming an alliance against him with Licinius,<ref>Barnes, ''Constantine and Eusebius'', 41.</ref> Constantine forged his own alliance with Licinius over the winter of 311–312 and offered him his sister [[Flavia Julia Constantia|Constantia]] in marriage. Maximinus considered Constantine's arrangement with Licinius an affront to his authority. In response, he sent ambassadors to Rome, offering political recognition to Maxentius in exchange for a military support, which Maxentius accepted.<ref>Barnes, ''Constantine and Eusebius'', 41; Elliott, ''Christianity of Constantine'', 44–45; Lenski, "Reign of Constantine" (CC), 69; Odahl, 96.</ref> According to Eusebius, inter-regional travel became impossible, and there was military buildup everywhere. There was "not a place where people were not expecting the onset of hostilities every day".<ref>Eusebius, ''Historia Ecclesiastica'' 8.15.1–2, qtd. and tr. in MacMullen, ''Constantine'', 65.</ref>

[[File:Battle of Constantine and Maxentius (detail-of-fresco-in-Vatican-Stanze) c1650 by Lazzaro Baldi after Giulio Romano at the University of Edinburgh.jpg|thumb|''Battle of Constantine and Maxentius'' (detail of part of a fresco by [[Giulio Romano (painter)|Giulio Romano]] in the Hall of Constantine in the [[Raphael Rooms]] in the [[Vatican Museums|Vatican]]), copy c. 1650 by [[Lazzaro Baldi]], now at the University of Edinburgh]]

Constantine's advisers and generals cautioned against preemptive attack on Maxentius;<ref>Barnes, ''Constantine and Eusebius'', 41; MacMullen, ''Constantine'', 71.</ref> even his soothsayers recommended against it, stating that the sacrifices had produced unfavourable omens.<ref>''Panegyrici Latini'' 12(9)2.5; Curran, 67.</ref> Constantine, with a spirit that left a deep impression on his followers, inspiring some to believe that he had some form of supernatural guidance,<ref>Curran, 67.</ref> ignored all these cautions.<ref>MacMullen, ''Constantine'', 70–71.</ref> Early in the spring of 312,<ref name="esyyqc">Barnes, ''Constantine and Eusebius'', 41; Odahl, 101.</ref> Constantine crossed the [[Cottian Alps]] with a quarter of his army, a force numbering about 40,000.<ref>''Panegyrici Latini'' 12(9)5.1–3; Barnes, ''Constantine and Eusebius'', 41; MacMullen, ''Constantine'', 71; Odahl, 101.</ref> The first town his army encountered was ''Segusium'' ([[Susa, Piedmont|Susa]], Italy), a heavily fortified town that shut its gates to him. Constantine ordered his men to set fire to its gates and scale its walls. He took the town quickly. Constantine ordered his troops not to loot the town and advanced into northern Italy.<ref name="esyyqc" />

At the approach to the west of the important city of Augusta Taurinorum ([[Turin]], Italy), Constantine met a large force of heavily armed Maxentian cavalry.<ref>Barnes, ''Constantine and Eusebius'', 41; Jones, 70; MacMullen, ''Constantine'', 71; Odahl, 101–02.</ref> In the ensuing [[Battle of Turin (312)|Battle of Turin]] Constantine's army encircled Maxentius' cavalry, [[Flanking maneuver|flanked]] them with his own cavalry, and dismounted them with blows from his soldiers' iron-tipped clubs. Constantine's armies emerged victorious.<ref>''Panegyrici Latini'' 12(9)5–6; 4(10)21–24; Jones, 70–71; MacMullen, ''Constantine'', 71; Odahl, 102, 317–18.</ref> Turin refused to give refuge to Maxentius' retreating forces, opening its gates to Constantine instead.<ref>Barnes, ''Constantine and Eusebius'', 41; Jones, 71; Odahl, 102.</ref> Other cities of the north Italian plain sent Constantine embassies of congratulation for his victory. He moved on to Milan, where he was met with open gates and jubilant rejoicing. Constantine rested his army in Milan until mid-summer 312, when he moved on to Brixia ([[Brescia]]).<ref>Barnes, ''Constantine and Eusebius'', 41–42; Odahl, 103.</ref>

Brescia's army was easily dispersed,<ref>Barnes, ''Constantine and Eusebius'', 42; Jones, 71; MacMullen, ''Constantine'', 71; Odahl, 103.</ref> and Constantine quickly advanced to [[Verona]] where a large Maxentian force was camped.<ref>Jones, 71; MacMullen, ''Constantine'', 71; Odahl, 103.</ref> [[Ruricius Pompeianus]], general of the Veronese forces and Maxentius' praetorian prefect,<ref>Jones, 71; Odahl, 103.</ref> was in a strong defensive position since the town was surrounded on three sides by the [[Adige]]. Constantine sent a small force north of the town in an attempt to cross the river unnoticed. Ruricius sent a large detachment to counter Constantine's expeditionary force but was defeated. Constantine's forces successfully surrounded the town and laid siege.<ref>Barnes, ''Constantine and Eusebius'', 42; Jones, 71; Odahl, 103.</ref> Ruricius gave Constantine the slip and returned with a larger force to oppose Constantine. Constantine refused to let up on the siege and sent only a small force to oppose him. In the desperately fought [[Battle of Verona (312)|encounter]] that followed, Ruricius was killed and his army destroyed.<ref>Barnes, ''Constantine and Eusebius'', 42; Jones, 71; Odahl, 103–04.</ref> Verona surrendered soon afterwards, followed by [[Aquileia]],<ref>Barnes, ''Constantine and Eusebius'', 42; Jones, 71; Lenski, "Reign of Constantine" (CC), 69; MacMullen, ''Constantine'', 71; Odahl, 104.</ref> Mutina ([[Modena]]),<ref>Jones, 71; MacMullen, ''Constantine'', 71.</ref> and [[Ravenna]].<ref>MacMullen, ''Constantine'', 71.</ref> The road to Rome was now wide open to Constantine.<ref>Barnes, ''Constantine and Eusebius'', 42; Curran, 67; Jones, 71.</ref>

[[File:Ponte Milvio-side view-antmoose.jpg|thumb|upright=1.8|right|The Milvian Bridge ([[Ponte Milvio]]) over the [[Tiber|River Tiber]], north of Rome, where Constantine and Maxentius fought in the [[Battle of the Milvian Bridge]]]]
Maxentius prepared for the same type of war he had waged against Severus and Galerius: he occupied Rome and prepared for a siege.<ref>Barnes, ''Constantine and Eusebius'', 42; Jones, 71; Odahl, 105.</ref> He still controlled Rome's [[Praetorian Guard]], was well-stocked with African grain, and was surrounded on all sides by the seemingly impregnable [[Aurelian Walls]]. He ordered all bridges across the [[Tiber]] cut, reportedly on the counsel of the gods,<ref>Jones, 71.</ref> and left the rest of central Italy undefended; Constantine secured that region's support without challenge.<ref>Odahl, 104.</ref> Constantine progressed slowly<ref name="BC42">Barnes, ''Constantine and Eusebius'', 42.</ref> along the ''[[Via Flaminia]]'',<ref>MacMullen, ''Constantine'', 72; Odahl, 107.</ref> allowing the weakness of Maxentius to draw his regime further into turmoil.<ref name="BC42" /> Maxentius' support continued to weaken: at chariot races on 27 October, the crowd openly taunted Maxentius, shouting that Constantine was invincible.<ref>Barnes, ''Constantine and Eusebius'', 42; Curran, 67; Jones, 71–72; Odahl, 107–8.</ref> Maxentius, no longer certain that he would emerge from a siege victorious, built a temporary boat bridge across the Tiber in preparation for a field battle against Constantine.<ref>Barnes, ''Constantine and Eusebius'', 42–43; MacMullen, ''Constantine'', 78; Odahl, 108.</ref> On 28 October 312, the sixth anniversary of his reign, he approached the keepers of the [[Sibylline Books]] for guidance. The keepers prophesied that, on that very day, "the enemy of the Romans" would die. Maxentius advanced north to meet Constantine in battle.<ref>Lactantius, ''De Mortibus Persecutorum'' 44.8; Barnes, ''Constantine and Eusebius'', 43; Curran, 67; Jones, 72; Odahl, 108.</ref>

==== Constantine adopts the Greek letters Chi Rho for Christ's initials ====
{{See also|Chi Rho}}
{{Main|Battle of the Milvian Bridge}}
{{Further|Ponte Milvio}}
[[File:Konstantinsmedaillon.jpg|thumb|Silver [[medallion]] of 315; Constantine with a [[chi-rho]] symbol as the crest of his [[Helmet of Constantine|helmet]]]]
Maxentius' forces were still twice the size of Constantine's, and he organised them in long lines facing the battle plain with their backs to the river.<ref name="bvubfs">Odahl, 108.</ref> Constantine's army arrived on the field bearing unfamiliar symbols on their standards and their shields.<ref>Barnes, ''Constantine and Eusebius'', 43; Digeser, 122; Jones, 72; Odahl, 106.</ref> According to Lactantius "Constantine was directed in a dream to cause the heavenly sign to be delineated on the shields of his soldiers, and so to proceed to battle. He did as he had been commanded, and he marked on their shields the letter Χ, with a perpendicular line drawn through it and turned round thus at the top, being the cipher of Christ. Having this sign (☧), his troops stood to arms."<ref>Lactantius, ''De Mortibus Persecutorum'' 44.4–6, tr. J.L. Creed, ''Lactantius: De Mortibus Persecutorum'' (Oxford: Oxford University Press, 1984), qtd. in Lenski, "Reign of Constantine" (CC), 71.</ref> Eusebius describes a vision that Constantine had while marching at midday in which "he saw with his own eyes the trophy of a cross of light in the heavens, above the sun, and bearing the inscription, ''In Hoc Signo Vinces''" ("In this sign thou shalt conquer").<ref>Eusebius, ''Vita Constantini'' 1.28, tr. Odahl, 105. Barnes, ''Constantine and Eusebius'', 43; Drake, "Impact of Constantine on Christianity" (CC), 113; Odahl, 105.</ref> In Eusebius' account, Constantine had a dream the following night in which Christ appeared with the same heavenly sign and told him to make an army standard in the form of the ''[[labarum]]''.<ref>Eusebius, ''Vita Constantini'' 1.27–29; Barnes, ''Constantine and Eusebius'', 43, 306; Odahl, 105–06, 319–20.</ref> Eusebius is vague about when and where these events took place,<ref>Drake, "Impact of Constantine on Christianity" (CC), 113.</ref> but it enters his narrative before the war begins against Maxentius.<ref>Cameron and Hall, 208.</ref> He describes the sign as [[Chi (letter)|Chi]] (Χ) traversed by [[Rho]] (Ρ) to form ☧, representing the first two letters of the Greek word {{lang|grc|ΧΡΙΣΤΟΣ}} (Christos).<ref>Barnes, ''Constantine and Eusebius'', 306; MacMullen, ''Constantine'', 73; Odahl, 319.</ref><ref>Cameron and Hall, 206–07; Drake, "Impact of Constantine on Christianity" (CC), 114; Nicholson, 311.</ref> A medallion was issued at [[Pavia|Ticinum]] in 315 which shows Constantine [[Helmet of Constantine|wearing a helmet]] emblazoned with the ''[[Chi Rho]]'',<ref>Lenski, "Reign of Constantine" (CC), 71, citing ''Roman Imperial Coinage'' 7 Ticinum 36.</ref> and coins issued at Siscia in 317/318 repeat the image.<ref>R. Ross Holloway, ''Constantine and Rome'' (New Haven: Yale University Press, 2004), 3, citing Kraft, "Das Silbermedaillon Constantins des Grosses mit dem Christusmonogram auf dem Helm", ''Jahrbuch für Numismatik und Geldgeschichte'' 5–6 (1954/55): 151–78.</ref> The figure was otherwise rare and is uncommon in imperial iconography and propaganda before the 320s.<ref>Lenski, "Reign of Constantine" (CC), 71.</ref> It was not completely unknown, however, being an abbreviation of the Greek word chrēston (good), having previously appeared on the coins of [[Ptolemy III Euergetes]] in the 3rd century BC. Following Constantine, centuries of Christians invoked the miraculous or the supernatural when justifying or describing their warfare.<ref>{{Cite book |title=Miracles, political authority and violence in medieval and early modern history |date=2022 |publisher=Routledge, Taylor & Francis Group |isbn=978-0-367-76728-0 |editor-last=Rowley |editor-first=Matthew |series=Themes in medieval and early modern history |location=London New York |editor-last2=Hodgson |editor-first2=Natasha R.}}</ref>

Constantine deployed his own forces along the whole length of Maxentius' line. He ordered his cavalry to charge, and they broke Maxentius' cavalry. He then sent his infantry against Maxentius' infantry, pushing many into the Tiber where they were slaughtered and drowned.<ref name="bvubfs" /> The battle was brief,<ref>Barnes, ''Constantine and Eusebius'', 43; Curran, 68.</ref> and Maxentius' troops were broken before the first charge.<ref>MacMullen, ''Constantine'', 78.</ref> His horse guards and praetorians initially held their position, but they broke under the force of a Constantinian cavalry charge; they also broke ranks and fled to the river. Maxentius rode with them and attempted to cross the bridge of boats ([[Ponte Milvio]]), but he was pushed into the Tiber and drowned by the mass of his fleeing soldiers.<ref>Barnes, ''Constantine and Eusebius'', 43; Curran, 68; Lenski, "Reign of Constantine" (CC), 70; MacMullen, ''Constantine'', 78; Odahl, 108.</ref>

==== In Rome ====
[[File:0 Gaius Flavius Valerius Constantinus, Palatino.jpg|thumb|Head of a [[bronze colossus of Constantine]], now in the [[Capitoline Museums]]<ref>[http://www.museicapitolini.org/it/percorsi/percorsi_per_sale/museo_del_palazzo_dei_conservatori/esedra_di_marco_aurelio/statua_colossale_bronzea_di_costantino_testa Head of the bronze colossus], Capitoline Museums</ref>
<!-- this is a difference stone head: <ref>{{cite web |url=http://www.metmuseum.org/art/collection/search/252884 |title=Portrait Head of the Emperor Constantine, Metropolitan Museum of Art, 26.229 |publisher=Metmuseum.org |date=28 June 2017 |access-date=28 June 2017}}</ref>-->
]]
Constantine entered Rome on 29 October 312{{sfn|Barnes|1981|loc=[https://books.google.com/books?id=LGDjJK-JeSwC&pg=PA44 p.&nbsp;44]}}<ref>MacMullen, ''Constantine'', 81; Odahl, 108.</ref> and staged a grand ''adventus'' in the city which was met with jubilation.<ref>Cameron, 93; Curran, 71–74; Odahl, 110.</ref> Maxentius' body was fished out of the Tiber and decapitated, and his head was paraded through the streets for all to see.<ref>Barnes, ''Constantine and Eusebius'', 44; Curran, 72; Jones, 72; Lenski, "Reign of Constantine" (CC), 70; MacMullen, ''Constantine'', 78; Odahl, 108.</ref> After the ceremonies, the disembodied head was sent to Carthage, and Carthage offered no further resistance.<ref>Barnes, ''Constantine and Eusebius'', 44–45.</ref> Unlike his predecessors, Constantine neglected to make the trip to the [[Capitoline Hill]] and perform customary sacrifices at the [[Temple of Jupiter Optimus Maximus|Temple of Jupiter]].<ref>Barnes, ''Constantine and Eusebius'', 44; MacMullen, ''Constantine'', 81; Odahl, 111. Cf. also Curran, 72–75.</ref> However, he did visit the Senatorial [[Curia Julia]],<ref>Barnes, ''Constantine and Eusebius'', 45; Curran, 72; MacMullen, ''Constantine'', 81; Odahl, 109.</ref> and he promised to restore its ancestral privileges and give it a secure role in his reformed government; there would be no revenge against Maxentius' supporters.<ref>Barnes, ''Constantine and Eusebius'', 45–46; Odahl, 109.</ref> In response, the [[Roman Senate|Senate]] decreed him "title of the first name", which meant that his name would be listed first in all official documents,<ref>Barnes, ''Constantine and Eusebius'', 46; Odahl, 109.</ref> and they acclaimed him as "the greatest augustus".<ref>Barnes, ''Constantine and Eusebius'', 46.</ref> He issued decrees returning property that was lost under Maxentius, recalling political exiles, and releasing Maxentius' imprisoned opponents.<ref>Barnes, ''Constantine and Eusebius'', 44.</ref>

An extensive propaganda campaign followed, during which Maxentius' image was purged from all public places. He was written up as a "tyrant" and set against an idealised image of Constantine the "liberator". Eusebius is the best representative of this strand of Constantinian propaganda.<ref>Barnes, ''Constantine and Eusebius'', 45–47; Cameron, 93; Curran, 76–77; Lenski, "Reign of Constantine" (CC), 70.</ref> Maxentius' rescripts were declared invalid, and the honours that he had granted to leaders of the Senate were also invalidated.<ref name="Barnes, CE, 45">Barnes, ''Constantine and Eusebius'', 45.</ref> Constantine also attempted to remove Maxentius' influence on Rome's urban landscape. All structures built by him were rededicated to Constantine, including the [[Santi Cosma e Damiano, Rome#History|Temple of Romulus]] and the [[Basilica of Maxentius]].<ref>Curran, 80–83.</ref> At the focal point of the basilica, a stone statue was erected of Constantine holding the Christian ''labarum'' in its hand. Its inscription bore the message which the statue illustrated: "By this sign, Constantine had freed Rome from the yoke of the tyrant."<ref>Barnes, ''Constantine and Eusebius'', 47.</ref>

Constantine also sought to upstage Maxentius' achievements. For example, the [[Circus Maximus]] was redeveloped so that its seating capacity was 25 times larger than that of Maxentius' racing complex on the [[Appian Way|Via Appia]].<ref>Curran, 83–85.</ref> Maxentius' strongest military supporters were neutralised when Constantine disbanded the Praetorian Guard and [[Equites singulares Augusti|Imperial Horse Guard]].<ref>Barnes, ''Constantine and Eusebius'', 45; Curran, 76; Odahl, 109.</ref> The tombstones of the Imperial Horse Guard were ground up and used in a basilica on the [[Via Labicana]],<ref>Curran, 101.</ref> and their former base was redeveloped into the [[Archbasilica of Saint John Lateran|Lateran Basilica]] on 9 November 312—barely two weeks after Constantine captured the city.<ref>Krautheimer, ''Corpus Basilicarum Christianarum Romanorum'', 5.90, cited in Curran, 93–96.</ref> The [[Legio II Parthica]] was removed from [[Albano Laziale]],<ref name="Barnes, CE, 45" /> and the remainder of Maxentius' armies were sent to do frontier duty on the Rhine.<ref>Odahl, 109.</ref>

==== Wars against Licinius ====
[[File:Aureus of Licinius.png|thumb|upright=1.2|Gold [[aureus]] of the emperor [[Licinius]]]]
In the following years, Constantine gradually consolidated his military superiority over his rivals in the crumbling Tetrarchy. In 313, he met Licinius in Milan to secure their alliance by the marriage of Licinius and Constantine's half-sister Constantia. During this meeting, the emperors agreed on the so-called [[Edict of Milan]],<ref>The term is a misnomer as the act of Milan was not an edict, while the subsequent edicts by Licinius—of which the edicts to the provinces of Bythinia and Palestine are recorded by Lactantius and Eusebius, respectively—were not issued in Milan.</ref> officially granting full tolerance to Christianity and all religions in the empire.<ref>Pohlsander, ''Emperor Constantine'', 25.</ref> The document had special benefits for Christians, legalising their religion and granting them restoration for all property seized during Diocletian's persecution. It repudiates past methods of religious coercion and used only general terms to refer to the divine sphere—"Divinity" and "Supreme Divinity", ''summa divinitas''.<ref>Drake, "Impact", 121–23.</ref> The conference was cut short, however, when news reached Licinius that his rival [[Maximinus Daza|Maximinus]] had crossed the Bosporus and invaded European territory. Licinius departed and eventually defeated Maximinus, gaining control over the entire eastern half of the Roman Empire. Relations between the two remaining emperors deteriorated, as Constantine suffered an assassination attempt at the hands of a character that Licinius wanted elevated to the rank of Caesar;<ref name="ReferenceA">Carrié & Rousselle, ''L'Empire Romain'', 229.</ref> Licinius, for his part, had Constantine's statues in Emona destroyed.<ref>Byfield, Ted, ed. ''The Christians: Their First Two Thousand Years''. vol. III. p. 148. {{cite web |url=http://www.christianhistoryproject.org/to-the-constantine-era/constantine |title=The sign in the sky that changed history |access-date=5 February 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160119071854/http://www.christianhistoryproject.org/to-the-constantine-era/constantine/ |archive-date=19 January 2016}}</ref> In either 314 or 316 the two augusti fought against one another at the [[Battle of Cibalae]], with Constantine being victorious. They clashed again at the [[Battle of Mardia]] in 317 and agreed to a settlement in which Constantine's sons [[Crispus]] and [[Constantine II (emperor)|Constantine II]], and Licinius' son [[Licinius II|Licinius Junior]] were made ''caesars''.<ref>Pohlsander, ''Emperor Constantine'', pp. 38–39.</ref>  After this arrangement, Constantine ruled the dioceses of Pannonia and Macedonia and took residence at [[Sirmium]], whence he could wage war on the Goths and Sarmatians in 322, and on the Goths in 323, defeating and killing their leader [[Rausimod]].<ref name="ReferenceA" />

In 320 Licinius allegedly reneged on the religious freedom promised by the Edict of Milan and began to oppress Christians anew,<ref>Pohlsander, ''Emperor Constantine'', pp. 41–42.</ref> generally without bloodshed, but resorting to confiscations and sacking of Christian office-holders.<ref>Carrié & Rousselle, ''L'Empire Romain'', pp. 229–30.</ref> Although this characterisation of Licinius as anti-Christian is somewhat doubtful, the fact is that he seems to have been far less open in his support of Christianity than Constantine. Therefore, Licinius was prone to see the Church as a force more loyal to Constantine than to the Imperial system in general,<ref>Timothy E. Gregory, ''A History of Byzantium''. Chichester: John Wiley & Sons, 2010, {{ISBN|978-1-4051-8471-7}}, p. 54.</ref> as the explanation offered by the Church historian [[Sozomen]].<ref>Philip Schaff, ed., ''Nicene and Post-nicene Fathers: Second Series''. New York: Cosimo, 2007, {{ISBN|978-1-60206-508-6}}, p. 418, footnote 6.</ref>

This dubious arrangement eventually became a challenge to Constantine in the West, climaxing in the great civil war of 324. Constantine's Christian eulogists present the war as a battle between Christianity and paganism; Licinius, aided by Gothic mercenaries, represented the past and ancient paganism, while Constantine and his [[Franks]] marched under the standard of the ''labarum''.{{citation needed|date=August 2021}} Outnumbered but fired by their zeal, Constantine's army emerged victorious in the [[Battle of Adrianople (324)|Battle of Adrianople]]. Licinius fled across the Bosphorus and appointed [[Martinian (emperor)|Martinian]], his ''[[magister officiorum]]'', as nominal augustus in the West, but Constantine next won the [[Battle of the Hellespont]] and finally the [[Battle of Chrysopolis]] on 18 September 324.<ref>Pohlsander, ''Emperor Constantine'', 42–43.</ref> Licinius and Martinian surrendered to Constantine at ''Nicomedia'' on the promise their lives would be spared: they were sent to live as private citizens in Thessalonica and Cappadocia respectively, but in 325 Constantine accused Licinius of plotting against him and had them both arrested and hanged; Licinius' son (the son of Constantine's half-sister) was killed in 326.<ref>Scarre, ''Chronicle of the Roman Emperors'', 215.</ref> Thus Constantine became the sole emperor of the Roman Empire.<ref name="macmullen">MacMullen, ''Constantine''.</ref>

=== Later rule ===

==== Foundation of Constantinople ====
{{further|New Rome}}
[[File:Silver medallion of Constantine I, AD 330.jpg|right|thumb|Coin struck by Constantine I to commemorate the founding of Constantinople]]
[[File:Glittica romana, costantino e la tyche di costantinopoli, sardonice IV sec.JPG|thumb|4th century sardonyx cameo with Constantine and the Tyche of Constantinople<ref>{{Cite book |url=https://books.google.com/books?id=hPX7EAAAQBAJ&pg=PA36 |title=The Early Reception and Appropriation of the Apostle Peter (60-800 CE): The Anchors of the Fisherman |date=2020-03-17 |publisher=BRILL |isbn=978-90-04-42568-2 |page=36 |language=en}}</ref>]]
Diocletian had chosen ''Nicomedia'' in the East as his capital during the Tetrarchy<ref>Sherrard, ed. Krieger, ''Byzantium'', Silver Burdett Company, Morristown, NJ, 1966 p. 15.</ref>—not far from Byzantium, well situated to defend Thrace, Asia, and Egypt, all of which had required his military attention.<ref>Sinnigen & Boak, ''A History of Rome to A.D. 565'', 6th ed., Macmillan Publishing Co., Inc., New York, 1977 pp. 409–10.</ref> Constantine had recognised the shift of the empire from the remote and depopulated{{why?|date=July 2024}} West to the richer cities of the East, and the military strategic importance of protecting the Danube from barbarian excursions and Asia from a hostile Persia in choosing his new capital<ref>Norwich, ''Byzantium: The Early Centuries'', Penguin Books, Middlesex, 1988, p. 40.</ref> as well as being able to monitor shipping traffic between the Black Sea and the Mediterranean.<ref>Sherrard, ed. Krieger, ''Byzantium'', Silver Burdett Company, Morristown, NJ, 1966 p. 18.</ref> Licinius' defeat came to represent the defeat of a rival centre of pagan and Greek-speaking political activity in the East, as opposed to the Christian and Latin-speaking Rome, and it was proposed that a new Eastern capital should represent the integration of the East into the Roman Empire as a whole, as a centre of learning, prosperity, and cultural preservation for the whole of the Eastern Roman Empire.<ref>Gilbert Dagron, ''Naissance d'une Capitale'',  24.</ref> Among the various locations proposed for this alternative capital, Constantine appears to have toyed earlier with [[History of Sofia|Serdica]] (present-day [[Sofia]]), as he was reported saying that "''Serdica is my Rome''".<ref>[[Petrus Patricius]] ''excerpta Vaticana'', 190: Κωνσταντίνος εβουλεύσατο πρώτον εν Σαρδική μεταγαγείν τά δημόσια· φιλών τε τήν πόλιν εκείνην συνεχώς έλεγεν "η εμή Ρώμη Σαρδική εστι."</ref> Sirmium and [[Thessalonica]] were also considered.<ref>Ramsey MacMullen, ''Constantine'', [[Routledge]] ed., 1987, 149.</ref> Eventually, however, Constantine decided to work on the Greek city of [[Byzantium]], which offered the advantage of having already been extensively rebuilt on Roman patterns of urbanism during the preceding century by Septimius Severus and [[Caracalla]], who had already acknowledged its strategic importance.<ref>Dagron, ''Naissance d'une Capitale'', 15/19.</ref> The city was thus founded in 324,<ref name=Oxf>"Constantinople" in ''The Oxford Dictionary of Byzantium'', [[Oxford University Press]], Oxford, 1991, p. 508. {{ISBN|0-19-504652-8}}</ref> dedicated on 11 May 330<ref name=Oxf /> and renamed ''Constantinopolis'' ("Constantine's City" or [[Constantinople]] in English). Special commemorative coins were issued in 330 to honour the event. The new city was protected by the relics of the [[True Cross]], the [[Rod of Moses]] and other holy relics, though a [[Cameo (carving)|cameo]] now at the [[Hermitage Museum]] also represented Constantine crowned by the [[tyche]] of the new city.<ref>[http://www.hermitagerooms.com/exhibitions/Byzantium/sardonyx.asp Sardonyx cameo depicting constantine the great crowned by Constantinople, 4th century AD] {{webarchive|url=https://web.archive.org/web/20060316221103/http://www.hermitagerooms.com/exhibitions/Byzantium/sardonyx.asp |date=16 March 2006 }} at "The Road to Byzantium: Luxury Arts of Antiquity". ''The Hermitage Rooms at Somerset House'' (30 March 2006&nbsp;– 3 September 2006).</ref> The figures of old gods were either replaced or assimilated into a framework of [[Christian symbolism]]. Generations later there was the story that a [[Vision (spirituality)|divine vision]] led Constantine to this spot, and an angel no one else could see led him on a circuit of the new walls.<ref>Philostorgius, ''Historia Ecclesiastica'' 2.9.</ref> The capital would often be compared to the 'old' Rome as ''Nova Roma Constantinopolitana'', the "New Rome of Constantinople".<ref name="macmullen" /><ref>According to the ''Reallexikon für Antike und Christentum'', vol. 164 (Stuttgart: A. Hiersemann, 2005), column 442, there is no evidence for the tradition that Constantine officially dubbed the city "New Rome" (''Nova Roma'' or ''Nea Rhome''). Commemorative coins that were issued during the 330s already refer to the city as ''Constantinopolis'' (Michael Grant, ''The Climax of Rome'' (London: Weidenfeld and Nicolson, 1968), 133). It is possible that the emperor called the city "Second Rome" (''Deutera Rhome'') by official decree, as reported by the 5th-century church historian Socrates of Constantinople.</ref>

==== Religious policy ====
{{Main|Religious policies of Constantine the Great}}
{{further|Constantinian shift|Constantine the Great and Christianity|Constantine the Great and Judaism}}
{{Infobox saint
| honorific_prefix   = [[Saint]]
| name               = Constantine the Great
| resting_place      = [[Constantinople]]
| feast_day          = 21 May
| venerated_in       = {{plainlist|
*[[Eastern Orthodox Church]]
<!-- Talk in talk page before adding Latin Catholicism or Roman Catholicism. -->
*[[Eastern Catholic Church]]{{efn|Constantine is not revered as a saint but as "the great" in the [[Latin Catholic Church]].<ref>{{Cite encyclopedia |url=https://www.newadvent.org/cathen/04295c.htm |encyclopedia=Catholic Encyclopedia |title=Constantine the Great |publisher=New Advent |access-date=9 January 2022}}</ref><ref>{{Cite web |url=http://faith.nd.edu/s/1210/faith/interior.aspx?sid=1210&gid=609&pgid=14724&cid=30276&ecid=30276&crid=0 |title=St. Constantine |work=FaithND |publisher=University of Notre Dame |access-date=9 January 2022}}</ref> [[Eastern Catholic Churches]] such as the [[Ukrainian Greek Catholic Church|Ukrainian Catholic Church]] may revere him as a saint.<ref>{{cite web |url=http://www.stconstantine.org/OurParish/OurPatronSaint/index.php |url-status=dead |title=Saint Constantine the Great |publisher=Saint Constantine Ukrainian Catholic Church |archive-url=https://web.archive.org/web/20200225192016/http://www.stconstantine.org:80/OurParish/OurPatronSaint/index.php |archive-date=25 February 2020}}</ref>}}
*[[Oriental Orthodoxy]]
*[[Anglican Communion]]
*[[Lutheran Church]]}}
| image              = Byzantinischer Mosaizist um 1000 002.jpg
| imagesize          = 250px
| caption            = [[Mosaic]] in the [[Hagia Sophia]], section: Maria as patron saint of Constantinople, detail: [[donor portrait]] of Emperor Constantine I with a model of the city
| titles             = Emperor and Equal to the Apostles
| major_shrine       = [[Church of the Holy Apostles]], Constantinople
}}
[[File:Constantine burning Arian books.jpg|thumb|upright=1.2|left|Constantine burning books by Arian heretics ('Heretici Arriani'), from a 9th-century manuscript now in [[Vercelli]]]]
Constantine was the first emperor to stop the persecution of Christians and to legalise Christianity, along with all other religions/cults in the Roman Empire. In February 313, he met with Licinius in Milan and developed the Edict of Milan, which stated that Christians should be allowed to follow their faith without oppression.<ref>{{Cite book |last=Bowder |first=Diana |title=The Age of Constantine and Julian |publisher=Barnes & Noble Books |year=1987 |isbn=9780064906012 |pages=28 |language=English}}</ref> This removed penalties for professing Christianity, under which [[Persecution of Christians in the Roman Empire|many had been martyred previously]], and it returned confiscated Church property. The edict protected all religions from persecution, not only Christianity, allowing anyone to worship any deity that they chose. A similar edict had been issued in 311 by Galerius, senior emperor of the Tetrarchy, which granted Christians the right to practise their religion but did not restore any property to them.<ref>See Lactantius, ''De Mortibus Persecutorum'' 34–35.</ref> The Edict of Milan included several clauses which stated that all confiscated churches would be returned, as well as other provisions for previously persecuted Christians. Some scholars think that Helena adopted Christianity as an adult, and according to Eusebius she was converted by Constantine,{{sfn|Young|2006|p=6 and n. 24}} but other historians debate whether Constantine adopted his mother Helena's Christianity in his youth or whether he adopted it gradually over the course of his life.<ref>R. Gerberding and J. H. Moran Cruz, ''Medieval Worlds'' (New York: Houghton Mifflin Company, 2004) p. 55.</ref>

[[File:Sylvester I and Constantine.jpg|thumb|upright=1.4|[[Pope Sylvester I]] and Emperor Constantine]]
Constantine possibly retained the title of ''[[pontifex maximus]]'' which emperors bore as heads of the ancient Roman religion until [[Gratian]] renounced the title.<ref>"[https://www.britannica.com/biography/Gratian-Roman-emperor Gratian]" Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 3 February 2008.</ref><ref name=livius>[https://www.livius.org/pn-po/pontifex/maximus.html Pontifex Maximus] {{Webarchive|url=https://web.archive.org/web/20130303013139/http://www.livius.org/pn-po/pontifex/maximus.html |date=3 March 2013 }} Livius article by Jona Lendering retrieved 21 August 2011.</ref> According to Christian writers, Constantine was over 40 when he finally declared himself a Christian, making it clear that he owed his successes to the protection of the Christian High God alone.<ref>[[Peter Brown (historian)|Peter Brown]], ''The Rise of Christendom'' 2nd edition (Oxford, Blackwell Publishing, 2003) p. 60.</ref> Despite these declarations of being a Christian, he waited to be baptised on his deathbed, believing that the baptism would release him of any sins he committed in the course of carrying out his policies while emperor.{{sfn|Drake|2000|p= 395}} He supported the Church financially, built basilicas, granted privileges to clergy (such as exemption from certain taxes), promoted Christians to high office, and returned property confiscated during the long period of persecution.<ref>R. Gerberding and J. H. Moran Cruz, ''Medieval Worlds'' (New York: Houghton Mifflin Company, 2004) pp. 55–56.</ref> His most famous building projects include the [[Church of the Holy Sepulchre]] and [[Old St. Peter's Basilica]]. In constructing the Old St. Peter's Basilica, Constantine went to great lengths to erect the basilica on top of [[Saint Peter|St. Peter]]'s resting place, so much so that it even affected the design of the basilica, including the challenge of erecting it on the hill where St. Peter rested, making its complete construction time over 30 years from the date Constantine ordered it to be built.

Constantine might not have patronised Christianity alone. A [[Arch of Constantine|triumphal arch]] was built in 315 to celebrate his victory in the Battle of the Milvian Bridge which was decorated with images of the goddess [[Victoria (mythology)|Victoria]], and sacrifices were made to pagan gods at its dedication, including [[Apollo]], [[Diana (mythology)|Diana]], and [[Hercules]]. Absent from the arch are any depictions of Christian symbolism. However, the arch was commissioned by the Senate, so the absence of Christian symbols may reflect the role of the [[Curia]] at the time as a pagan redoubt.<ref>Robin Lane Fox, ''apud'' Jonathan Bardill, '' Constantine, Divine Emperor of the Christian Golden Age''. Cambridge University Press, 2011, {{ISBN|978-0-521-76423-0}}, p. 307, note 27.</ref>

In 321, he legislated that the ''venerable Sunday'' should be a day of rest for all citizens.<ref>''[[Codex Justinianeus]]'' 3.12.2.</ref> In 323, he issued a decree banning Christians from participating in state sacrifices.<ref>''[[Codex Theodosianus]]'' 16.2.5.</ref> After the pagan gods had disappeared from his coinage, Christian symbols appeared as Constantine's attributes, the chi rho between his hands or on his labarum,<ref>Cf. Paul Veyne, ''Quand notre monde est devenu chrétien'', 163.</ref> as well on the coinage.<ref name="ramsey">R. MacMullen, "Christianizing The Roman Empire A.D. 100–400, Yale University Press, 1984, p. 44, {{ISBN|0-300-03642-6}}</ref> The reign of Constantine established a precedent for the emperor to have great influence and authority in the early Christian councils, most notably the dispute over Arianism. Constantine disliked the risks to societal stability that religious disputes and controversies brought with them, preferring to establish an orthodoxy.<ref>Richards, Jeffrey. ''The Popes and the Papacy in the Early Middle Ages 476–752'' (London: Routledge & Kegan Paul, 1979) 14–15; ''The Popes and the Papacy in the Early Middle Ages 476–752'' (London: Routledge & Kegan Paul, 1979) 15.</ref> His influence over the Church councils was to enforce doctrine, root out heresy, and uphold ecclesiastical unity; the Church's role was to determine proper worship, doctrines, and dogma.<ref>Richards, Jeffrey. ''The Popes and the Papacy in the Early Middle Ages 476–752'' (London: Routledge & Kegan Paul, 1979) pp. 15–16.</ref>

North African bishops struggled with Christian bishops who had been ordained by Donatus in opposition to [[Caecilianus|Caecilian]] from 313 to 316. The African bishops could not come to terms, and the Donatists asked Constantine to act as a judge in the dispute. Three regional Church councils and another trial before Constantine all ruled against Donatus and the [[Donatism]] movement in North Africa. In 317, Constantine issued an edict to confiscate Donatist church property and to send Donatist clergy into exile.<ref>Frend, W.H.C., "The Donatist Church; A Movement of Protest in Roman North Africa," (1952 Oxford), pp. 156–162.</ref> More significantly, in 325 he summoned the First Council of Nicaea, most known for its dealing with Arianism and for instituting the [[Nicene Creed]].<ref>{{Cite book |last=Norwich |first=John Julius |title=Byzantium |year=1996 |isbn=0394537785 |edition=First American |location=New York |publisher=Alfred A. Knopf |pages=54–57 |oclc=18164817}}</ref> He enforced the council's prohibition against celebrating the Lord's Supper on the day before the Jewish [[Passover]], which marked a definite break of Christianity from the Judaic tradition. From then on, the solar [[Julian calendar]] was given precedence over the lunisolar [[Hebrew calendar]] among the Christian churches of the Roman Empire.<ref>{{Cite web |url=https://www.newadvent.org/fathers/25023.htm |title=Church Fathers: Life of Constantine, Book III (Eusebius), chapter 18 |website=New Advent}}</ref>

Constantine made some new laws regarding the Jews; some of them were unfavourable towards Jews, although they were not harsher than those of his predecessors.<ref name="Goldsworthy187">Cf. Adrian Goldsworthy, ''How Rome Fell'', 187.</ref> It was made illegal for Jews to seek converts or to attack other Jews who had converted to Christianity.<ref name="Goldsworthy187" /> They were forbidden to own Christian slaves or to [[brit milah|circumcise]] their slaves.<ref>{{Cite book |last=Stemberger |first=Gunter |url=https://books.google.com/books?id=BXuxAwAAQBAJ&pg=PA37 |title=Jews and Christians in the Holy Land |publisher=A&C Black |year=1999 |pages=37–38 |isbn=978-0-567-23050-8 |quote=If a Jew has bought and circumcised a Christian slave or one belonging to any other religious community, he may under no circumstances keep the circumcised person in slavery; rather, whoever suffers such a thing shall obtain the privilege of freedom.}}</ref><ref>{{Cite book |last=Schäfer |first=Peter |url=https://books.google.com/books?id=tdKCAgAAQBAJ&pg=PA182 |title=The History of the Jews in the Greco-Roman World |publisher=Routledge |year=2003 |page=182 |isbn=978-1-134-40317-2 |quote=Constantine forbade the circumcision of Christian slaves, and declared any slave circumcised despite this prohibition a free man}}</ref> On the other hand, Jewish clergy were given the same exemptions as Christian clergy.<ref name="Goldsworthy187" /><ref>Cameron, 107.</ref>

==== Administrative reforms ====
[[File:Gold coin pendant BM.JPG|thumb|right|Hexagonal gold pendant with double [[Solidus (coin)|solidus]] of Constantine the Great in the centre, AD&nbsp;321, now in the [[British Museum]]]]
Beginning in the mid-3rd century, the emperors began to favour members of the [[Equites|equestrian order]] over senators, who had a monopoly on the most important offices of the state. Senators were stripped of the command of legions and most provincial governorships, as it was felt that they lacked the specialised military upbringing needed in an age of acute defense needs;<ref>Christol & Nony, ''Rome et son Empire'', 241.</ref> such posts were given to equestrians by Diocletian and his colleagues, following a practice enforced piecemeal by their predecessors. The emperors, however, still needed the talents and the help of the very rich, who were relied on to maintain social order and cohesion by means of a web of powerful influence and contacts at all levels. Exclusion of the old senatorial aristocracy threatened this arrangement.

In 326 Constantine reversed this pro-equestrian trend, raising many administrative positions to senatorial rank and thus opening these offices to the old aristocracy; at the same time, he elevated the rank of existing equestrian office-holders to senator, degrading the equestrian order in the process (at least as a bureaucratic rank).<ref>As equestrian ''order'' refers to people of equestrian ''census'' that had an actual position in the state bureaucracy, thousands of whom had no state function; cf. [[Claude Lepelley]], "Fine delle' ordine equestre: le tappe delle'unificazione dela classe dirigente romana nel IV secolo", IN Giardina, ed., ''Società romana e impero tardoantico'', Bari: Laterza, 1986, V. 1, quoted by Carrié & Rouselle, p. 660.</ref> The title of ''perfectissimus'' was granted only to mid- or low-level officials by the end of the 4th century.

By the new Constantinian arrangement, one could become a senator by being elected [[praetor]] or by fulfilling a function of senatorial rank.<ref>Christol & Nony, ''Rome et son Empire'', 247; Carrié & Rousselle ''L'Empire Romain'', 658.</ref> From then on, holding actual power and social status were melded together into a joint imperial hierarchy. Constantine gained the support of the old nobility with this,<ref>Carrié & Rousselle ''L'Empire Romain'', 658–59.</ref> as the Senate was allowed to elect praetors and [[quaestor]]s in place of the usual practice of the emperors directly creating magistrates (''adlectio''). An inscription in honour of [[Praefectus urbi|city prefect]] [[Ceionius Rufius Albinus|Ceionius Rufus Albinus]] states that Constantine had restored the Senate "the ''[[auctoritas]]'' it had lost at Caesar's time".<ref>{{citation |title=Inscriptiones Latinae Selectae |url=http://oracle-vm.ku-eichstaett.de:8888/epigr/epieinzel_de?p_belegstelle%3DCIL%2B06%252C%2B01708%26r_sortierung%3DBelegstelle |access-date=5 February 2016 |url-status=dead |archive-url=https://web.archive.org/web/20120720213655/http://oracle-vm.ku-eichstaett.de:8888/epigr/epieinzel_de?p_belegstelle=CIL%2B06%2C%2B01708&r_sortierung=Belegstelle |archive-date=20 July 2012}}; {{citation |author=Carrié & Rousselle |title=L'Empire Romain |page=659}}</ref>

The Senate as a body remained devoid of any significant power; nevertheless, the senators had been marginalised as potential holders of imperial functions during the 3rd century but could dispute such positions alongside more upstart bureaucrats.<ref>Carrié & Rousselle, ''L'Empire Romain'', 660.</ref> Some modern historians see in those administrative reforms an attempt by Constantine at reintegrating the senatorial order into the imperial administrative elite to counter the possibility of alienating pagan senators from a Christianised imperial rule;<ref>Cf. Arnhein, ''The Senatorial Aristocracy in the Later Roman Empire'', quoted by Perry Anderson, ''Passages from Antiquity to Feudalism'', 101.</ref> however, such an interpretation remains conjectural, given the fact that we do not have the precise numbers about pre-Constantine conversions to Christianity in the old senatorial milieu. Some historians suggest that early conversions among the old aristocracy were more numerous than previously supposed.<ref>Carrié & Rousselle, p.657 citing T.D. Barnes, "Statistics and the Conversion of the Roman Aristocracy", ''Journal of Roman Studies'', 85, 1995.</ref>

Constantine's reforms had to do only with the civilian administration. The military chiefs had risen from the ranks since the [[Crisis of the Third Century]]<ref>Cf. Paul Veyne, ''L'Empire Gréco-Romain'', 49.</ref> but remained outside the Senate, in which they were included only by Constantine's children.<ref>Christol & Nony, ''Rome et son Empire'', 247.</ref>

==== Monetary reforms ====
[[File:Nummus of Constantine (YORYM 2001 10313) obverse.jpg|thumb|left|A [[nummus]] of Constantine]]
In the 3rd century the production of [[fiat money]] to pay for public expenses resulted in [[Crisis of the Third Century#Economic impact|runaway inflation]], and Diocletian tried unsuccessfully to re-establish trustworthy minting of silver coins, as well as silver-bronze "[[Billon (alloy)|billon]]" coins (the term "billon" meaning an alloy of precious and base metals that is mostly base metal). Silver currency was overvalued in terms of its actual metal content and therefore could only circulate at much discounted rates. Constantine stopped minting the Diocletianic "pure" silver ''[[argenteus]]'' soon after 305, while the "billon" currency continued to be used until the 360s. From the early 300s on, Constantine forsook any attempts at restoring the silver currency, preferring instead to concentrate on minting large quantities of the gold [[solidus (coin)|solidus]], 72 of which made a pound of gold. New and highly debased silver pieces continued to be issued during his later reign and after his death, in a continuous process of retariffing, until this "billon" minting ceased in 367, and the silver piece was continued by various denominations of bronze coins, the most important being the ''[[centenionalis]]''.<ref>Walter Scheidel, "The Monetary Systems of the Han and Roman Empires", 174/175.</ref>

These bronze pieces continued to be devalued, assuring the possibility of keeping fiduciary minting alongside a gold standard. The author of ''[[De rebus bellicis|De Rebus Bellicis]]'' held that the rift widened between classes because of this monetary policy; the rich benefited from the stability in purchasing power of the gold piece, while the poor had to cope with ever-degrading bronze pieces.<ref>''De Rebus Bellicis'', 2.</ref> Later emperors such as [[Julian (emperor)|Julian the Apostate]] insisted on trustworthy mintings of the bronze currency.<ref>Sandro Mazzarino, according to Christol & Nony, ''Rome et son Empire'', 246.</ref>

Constantine's monetary policies were closely associated with his religious policies; increased minting was associated with the confiscation of all gold, silver, and bronze statues from pagan temples between 331 and 336 which were declared to be imperial property. Two imperial commissioners for each province had the task of getting the statues and melting them for immediate minting, with the exception of a number of bronze statues that were used as public monuments in Constantinople.<ref>Carrié & Rousselle, ''L'Empire Romain'', 245–246.</ref>

==== Executions of Crispus and Fausta ====
{{multiple image|total_width=350
|image1=Crispus.jpg
|caption1=Gold coin of Constantine's eldest son [[Crispus]], who was executed by his father
|image2=P1070865 Louvre tête de Fausta Ma4881 rwk.JPG
|caption2=Bust of Constantine's wife [[Fausta]], in the [[Louvre]], Paris
}}
Constantine had his eldest son Crispus seized and put to death by "cold poison" at Pola ([[Pula]], Croatia) sometime between 15 May and 17 June 326.<ref>Guthrie, 325–326.</ref> In July, he had his wife Empress Fausta (stepmother of Crispus) killed in an overheated bath.<ref>Guthrie, 326; Woods, "Death of the Empress", 70–72.</ref> Their names were wiped from the face of many inscriptions, references to their lives were eradicated from the literary record, and their memory was condemned. Eusebius, for example, edited out any praise of Crispus from later copies of ''[[Church History (Eusebius)|Historia Ecclesiastica]]'', and his ''[[Life of Constantine|Vita Constantini]]'' contains no mention of Fausta or Crispus.<ref>Guthrie, 326; Woods, "Death of the Empress", 72.</ref> Few ancient sources are willing to discuss possible motives for the events, and the few that do are of later provenance and are generally unreliable.<ref name="google">{{cite book |title=Encyclopedia of Roman Empire |date=2008 |publisher=MobileReference.com |isbn=978-1-60501-314-5 |url=https://books.google.com/books?id=62Qf64DdGu0C |access-date=5 October 2014}}</ref> At the time of the executions it was commonly believed that Empress Fausta was either in an illicit relationship with Crispus or was spreading rumours to that effect. A popular myth arose, modified to allude to the [[Hippolytus of Athens|Hippolytus]]–[[Phaedra (mythology)|Phaedra]] legend, with the suggestion that Constantine killed Crispus and Fausta for their immoralities;<ref name="GUTH326.7">Guthrie, 326–27.</ref> the largely fictional ''Passion of Artemius'' explicitly makes this connection.<ref>''Art. Pass'' 45; Woods, "Death of the Empress", 71–72.</ref> The myth rests on slim evidence as an interpretation of the executions; only late and unreliable sources allude to the relationship between Crispus and Fausta, and there is no evidence for the modern suggestion that Constantine's "godly" edicts of 326 and the irregularities of Crispus are somehow connected.<ref name="GUTH326.7" />

Although Constantine created his apparent heirs "caesars", following a pattern established by Diocletian, he gave his creations a hereditary character, alien to the tetrarchic system: Constantine's caesars were to be kept in the hope of ascending to empire and entirely subordinated to their augustus, as long as he was alive.<ref>Christol & Nony, ''Rome et son Empire'', 237/238.</ref> Adrian Goldsworthy speculates an alternative explanation for the execution of Crispus was Constantine's desire to keep a firm grip on his prospective heirs, this—and Fausta's desire for having her sons inheriting instead of their half-brother—being reason enough for killing Crispus; the subsequent execution of Fausta, however, was probably meant as a reminder to her children that Constantine would not hesitate in "killing his own relatives when he felt this was necessary".<ref>Cf. Adrian Goldsworthy, ''How Rome Fell'', 189 & 191.</ref>

==== Later campaigns ====
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|caption2=Gold medallion struck at [[Nicomedia]] in 335–336 to celebrate the 30th anniversary of his rule
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Constantine considered Constantinople his capital and permanent residence. He lived there for a good portion of his later life. In 328, construction was completed on [[Constantine's Bridge (Danube)|Constantine's Bridge]] at ''[[Sucidava]]'', (today [[Corabia|Celei]] in [[Romania]])<ref>Madgearu, Alexandru
(2008). Istoria Militară a Daciei Post Romane 275–376. Cetatea de Scaun. {{ISBN|978-973-8966-70-3}}, pp. 64–126.</ref> in hopes of reconquering [[Roman Dacia|Dacia]], a province that had been abandoned under Aurelian. In the late winter of 332, Constantine campaigned with the [[Sarmatians]] against the [[Goths]]. The weather and lack of food reportedly cost the Goths dearly before they submitted to Rome. In 334, after Sarmatian commoners had overthrown their leaders, Constantine led a campaign against the tribe. He won a victory in the war and extended his control over the region, as remains of camps and fortifications in the region indicate.<ref>Barnes, ''Constantine and Eusebius'', 250.</ref> Constantine resettled some Sarmatian exiles as farmers in Illyrian and Roman districts and conscripted the rest into the army. Constantine reconquered the South of Dacia and the new frontier in Dacia was along the wall and ditch called [[Brazda lui Novac]] line supported by new ''[[castra]]''.<ref>Madgearu, Alexandru(2008). Istoria Militară a Daciei Post Romane 275–376. Cetatea de Scaun. {{ISBN|978-973-8966-70-3}}, pp. 64–126.</ref> Constantine took the title ''Dacicus maximus'' in 336.<ref>Odahl, 261.</ref>

In the last years of his life, Constantine made plans for a campaign against [[Sasanian Empire|Persia]]. In a letter written to the king of Persia, [[Shapur II|Shapur]], Constantine had asserted his patronage over Persia's Christian subjects and urged Shapur to treat them well.<ref>Eusebius, ''VC'' 4.9ff, cited in Barnes, ''Constantine and Eusebius'', 259.</ref> The letter is undatable. In response to border raids, Constantine sent Constantius to guard the eastern frontier in 335. In 336, Prince Narseh invaded Armenia (a Christian kingdom since 301) and installed a Persian client on the throne. Constantine then resolved to campaign against Persia. He treated the war as a Christian crusade, calling for bishops to accompany the army and commissioning a tent in the shape of a church to follow him everywhere. Constantine planned to be baptised in the [[Jordan River]] before crossing into Persia. Persian diplomats came to Constantinople over the winter of 336–337, seeking peace, but Constantine turned them away. The campaign was called off, however, when Constantine became sick in the spring of 337.<ref>Barnes, ''Constantine and Eusebius'', 258–59. See also: Fowden, "Last Days", 146–48, and Wiemer, 515.</ref>

==== Illness and death ====
[[File:Raphael Baptism Constantine.jpg|thumb|''[[The Baptism of Constantine]]'', as imagined by students of [[Raphael]]]]
{{multiple image
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|footer=Constantine's sons and successors: [[Constantine II (emperor)|Constantine II]], [[Constantius II]], and [[Constans]]
}}
From his recent illness, Constantine knew death would soon come. Within the [[Church of the Holy Apostles]], which he had built in Constantinople, Constantine had secretly prepared a final resting-place for himself.<ref>Eusebius, ''Vita Constantini'' 4.58–60; Barnes, ''Constantine and Eusebius'', 259.</ref> It came sooner than he had expected. Soon after the Feast of Easter 337, Constantine fell seriously ill.<ref>Eusebius, ''Vita Constantini'' 4.61; Barnes, ''Constantine and Eusebius'', 259.</ref> He left Constantinople for the hot baths near his mother's city of [[Helenopolis (Bithynia)|Helenopolis]] ([[Altınova]]), on the southern shores of the Gulf of Nicomedia (present-day [[Gulf of İzmit]]). There, in a church his mother built in honour of [[Lucian of Antioch|Lucian the Martyr]], he prayed, and there he realised that he was dying. Seeking purification, he became a [[Catechesis|catechumen]] and attempted a return to Constantinople, making it only as far as a suburb of ''Nicomedia''.<ref>Eusebius, ''Vita Constantini'' 4.62.</ref> He summoned the bishops and told them of his hope to be baptised in the River Jordan, where Christ was written to have been baptised. He requested the baptism right away, promising to live a more Christian life should he live through his illness. The bishops, Eusebius records, "performed the sacred ceremonies according to custom".<ref>Eusebius, ''Vita Constantini'' 4.62.4.</ref> He chose the [[Arianism|Arian]] bishop [[Eusebius of Nicomedia]], bishop of the city where he lay dying, as his baptiser.<ref>Pohlsander, ''Emperor Constantine'', 75–76; Lenski, "Reign of Constantine" (CC), 82.</ref> In postponing his baptism, he followed one custom at the time which postponed baptism until after infancy.{{efn|Because he was so old, he could not be submerged in water to be baptised, and therefore, the rules of baptism were changed to what they are today, having water placed on the forehead alone. In this period infant baptism, though practiced (usually in circumstances of emergency) had not yet become a matter of routine in the west. Thomas M. Finn, ''Early Christian Baptism and the Catechumenate: East and West Syria'' (Collegeville: The Liturgical Press/Michael Glazier, 1992); Philip Rousseau, "Baptism," in ''Late Antiquity: A Guide to the Post Classical World'', ed. G.W. Bowersock, Peter Brown, and Oleg Grabar (Cambridge, MA: Belknap Press, 1999).}} It has been thought that Constantine put off baptism as long as he did so as to be absolved from as much of his sin as possible.<ref>{{cite book | last=Amerise | first=Marilena | year=2005 | title=Il battesimo di Costantino il Grande: storia di una scomoda eredità | trans-title=The baptism of Constantine the Great: The story of an uncomfortable legacy | language=it | publication-place=Stuttgart | publisher=Franz Steiner Verlag | series=[[Hermes (classical philology journal)|Hermes: Bulletin for Classical Philology]], supplements | issn=0341-0064 | isbn=978-3-515-08721-6 | url=https://books.google.com/books?id=am2Wv6gxBjEC | oclc=61029662}}<!-- Note: The [https://books.google.com/books?id=am2Wv6gxBjEC&pg=PA4 printed] {{ISBN|3-515-08679-X}} was also used for another work. --></ref> Constantine died soon after at a suburban villa called Achyron, on the last day of the fifty-day festival of [[Pentecost]] directly following Pascha (or [[Easter]]), on 22 May 337.<ref>Eusebius, ''Vita Constantini'' 4.64; Fowden, "Last Days of Constantine", 147; Lenski, "Reign of Constantine" (CC), 82.</ref>

Although Constantine's death follows the conclusion of the Persian campaign in Eusebius's account, most other sources report his death as occurring in its middle. Emperor Julian (a nephew of Constantine), writing in the mid-350s, observes that the Sassanians escaped punishment for their ill-deeds, because Constantine died "in the middle of his preparations for war".<ref>Julian, ''Orations'' 1.18.b.</ref> Similar accounts are given in the ''[[Origo Constantini]]'', an anonymous document composed while Constantine was still living, which has Constantine dying in ''Nicomedia'';<ref>''Origo Constantini'' 35.</ref> the ''Historiae abbreviatae'' of Sextus [[Aurelius Victor]], written in 361, which has Constantine dying at an estate near ''Nicomedia'' called Achyrona while marching against the Persians;<ref>Sextus Aurelius Victor, ''Historiae abbreviatae'' XLI.16.</ref> and the ''Breviarium'' of [[Eutropius (historian)|Eutropius]], a handbook compiled in 369 for the Emperor [[Valens]], which has Constantine dying in a nameless state villa in ''Nicomedia''.<ref>Eutropius, ''Breviarium'' X.8.2.</ref> From these and other accounts, some have concluded that Eusebius's ''Vita'' was edited to defend Constantine's reputation against what Eusebius saw as a less congenial version of the campaign.<ref>Fowden, "Last Days of Constantine", 148–49.</ref>

[[File:Sarcophagi Byzantine emperors Istanbul (11).JPG|thumb|left|A fragment of a [[Porphyry (geology)|porphyry]] sarcophagus that is believed to be Constantine's.]]
Following his death, his body was transferred to Constantinople and buried in the Church of the Holy Apostles,<ref>Pohlsander, ''Emperor Constantine'', 75–76.</ref> in a [[Porphyry (geology)|porphyry sarcophagus]] that was described in the 10th century by [[Constantine VII|Constantine VII Porphyrogenitus]] in the ''[[De Ceremoniis]]''.<ref>{{cite journal |author=A. A. Vasiliev |title=Imperial Porphyry Sarcophagi in Constantinople |journal=Dumbarton Oaks Papers |volume=4 |date=1848 |pages=1+3–26 |url=https://lucazavagno.files.wordpress.com/2012/12/vasiliev.pdf |archive-url=https://web.archive.org/web/20191231151500/https://lucazavagno.files.wordpress.com/2012/12/vasiliev.pdf |archive-date=31 December 2019 |url-status=live |doi=10.2307/1291047 |jstor=1291047}}</ref> His body survived the plundering of the city during the [[Fourth Crusade]] in 1204 but was destroyed at some point afterwards.<ref>{{Cite book |url=https://books.google.com/books?id=teyNhL3AuGEC&q=body%20of%20constantine%20the%20great&pg=PA305 |title=Russian Travelers to Constantinople in the Fourteenth and Fifteenth Centuries |via=Google Knihy |date=1984 |access-date=15 April 2017 |isbn=978-0-88402-101-8 |last1=Majeska |first1=George P |publisher=Dumbarton Oaks }}</ref> A fragment of a sarcophagus that is believed to be Constantine's is currently on display at the [[Istanbul Archaeology Museums]].

Constantine was succeeded by his three sons born of Fausta, Constantine II, [[Constantius II]] and [[Constans]]. His sons, along with his nephew [[Dalmatius]], had already received one division of the empire each to administer as caesars; Constantine may have intended his successors to resume a structure akin to Diocletian's Tetrarchy.<ref>{{cite book |last1=Edward J. Watts |title=The Final Pagan Generation: Rome's Unexpected Path to Christianity |date=2020 |publisher=University of California Press |isbn=9780520379220 |page=83}}</ref> A number of relatives were killed by followers of Constantius, notably Constantine's nephews Dalmatius (who held the rank of caesar) and [[Hannibalianus]], presumably to eliminate possible contenders to an already complicated succession. He also had two daughters, [[Constantina]] and [[Helena (wife of Julian)|Helena]], wife of Emperor Julian.<ref>Pohlsander, ''Emperor Constantine'', 71, figure 9.</ref>

== Assessment and legacy ==
{{Integralism |expanded=people}}
[[File:Colossus of Constantine I 03.jpg|left|thumb|Reconstructed version of the Colossus of Constantine at the Capitoline Museum in 2024]]
Constantine reunited the empire under one emperor, and he won major victories over the Franks and Alamanni in 306–308, the Franks again in 313–314, the Goths in 332, and the Sarmatians in 334. By 336, he had reoccupied most of the long-lost province of Dacia which Aurelian had been forced to abandon in 271. At the time of his death, he was planning a great expedition to end raids on the eastern provinces from the Persian Empire.<ref>Pohlsander, ''Emperor Constantine'', 72.</ref>

In the cultural sphere, Constantine revived the clean-shaven face fashion of earlier emperors, originally introduced among the Romans by [[Scipio Africanus]] (236–183 BC) and changed into the wearing of the [[beard#Rome|beard]] by [[Hadrian]] (r. 117–138). With some departures, such as [[Julian (emperor)|Julian the Apostate]] (r. 360–363), this new Roman imperial fashion lasted until the reign of [[Phocas]] (r. 602–610) in the 7th century.<ref>{{cite web |url=http://www.byzantium.gr/statfirst.html|last=Byzantine Chronicle |title=Imperial first times/last times |access-date=4 December 2024}}</ref><ref>{{cite web |url=http://www.forumancientcoins.com/numiswiki/view.asp?key=Barba |title=Barba – NumisWiki, The Collaborative Numismatics Project |publisher=Forum Ancient Coins |access-date=7 November 2012}}</ref>{{Better source needed|date=May 2025}}

The [[Holy Roman Empire]] reckoned Constantine among the venerable figures of its tradition. In the later Byzantine state, it became a great honour for an emperor to be hailed as a "new Constantine"; ten emperors carried the name, including the last emperor of the Eastern Roman Empire.<ref>Pohlsander, ''Emperor Constantine'', 91.</ref> [[Charlemagne]] used monumental Constantinian forms in his court to suggest that he was Constantine's successor and equal. Charlemagne, [[Henry VIII]], [[Philip II of Spain]], [[Godfrey of Bouillon]], [[House of Capet]], [[House of Habsburg]], [[House of Stuart]], [[Macedonian dynasty]] and [[Phokas (Byzantine family)|Phokas family]] claimed descent from Constantine.<ref>{{cite book |url=https://books.google.com/books?id=9DXZY2giQOAC&pg=PA34 |page=34 |title=The Italian Romance Epic in the Age of Humanism: The Matter of Italy and the World of Rome |author=Jane E. Everson |publisher=Oxford University Press |date=2001 |isbn=978-0-19-816015-1}}</ref><ref>{{cite book |url=https://books.google.com/books?id=XGXVO8aOg1QC&pg=PA17 |page=17 |title=Empire and Nation in Early English Renaissance Literature |publisher=Boydell & Brewer Ltd |date=2008 |author=Stewart James Mottram |isbn=978-1843841821}}</ref><ref>{{cite book |url=https://books.google.com/books?id=lV9Xdn3c6IoC&pg=PA135 |page=135 |title=Clio and the Crown: The Politics of History in Medieval and Early Modern Spain |author=Richard L. Kagan |date=2009 |publisher=JHU Press |isbn=978-1421401652}}</ref><ref>{{cite book |url=https://books.google.com/books?id=CSZQ-VPFKoMC&pg=PA187 |page=187 |author=Paul Magdalino |title=Byzantinum in the Year 1000 |publisher=Brill |date=2003 |isbn=9004120971}}</ref><ref>{{cite book |url=https://books.google.com/books?id=JTWAEAAAQBAJ&pg=PA91 |title=John Zonaras' Epitome of Histories: A Compendium of Jewish-Roman History and Its Reception |date=2022 |author=Theofili Kampianaki |publisher=Oxford University Press |page=91 |isbn=978-0-19-268858-3}}</ref><ref name="Marshall2000">{{cite book |author=Tristan Marshall |title=Theatre and Empire: Great Britain on the London Stages under James VI and I |url=https://books.google.com/books?id=Vje2I7_1njwC&pg=PA36 |access-date=14 December 2012 |date=18 November 2000 |publisher=Manchester University Press |isbn=978-0-7190-5748-9 |pages=36–7}}</ref><ref>{{cite book |url=https://books.google.com/books?id=CAFREAAAQBAJ&pg=PA22 |title=An Empire of Memory: The Legend of Charlemagne, the Franks, and Jerusalem before the First Crusade |publisher=Oxford University Press |page=22 |date=2011 |isbn=978-0-19-161640-2}}</ref><ref>{{cite book |url=https://books.google.com/books?id=mRkpAAAAYAAJ&pg=PA670 |title=The English Historical Review, Volume 2 |author1=Mandell Creighton |author2=Justin Winsor |author3=Samuel Rawson Gardiner |author4=Reginald Lane Poole |author5=Sir John Goronwy Edwards |page=670 |publisher=Oxford University Press |date=1887}}</ref><ref>{{cite book |url=https://books.google.com/books?id=MJB2DwAAQBAJ&pg=PA204 |page=204 |title=The Cambridge Companion to the Literature of the Crusades |publisher=Cambridge University Press |date=2019 |author=Anthony Bale |isbn=9781108474511}}</ref>{{Citation overkill|date=January 2025}} [[Geoffrey of Monmouth]] embroidered a tale that the legendary king of Britain, [[King Arthur]], was also a descendant of Constantine.<ref>Mulligan, pp. 262–264.</ref> Constantine acquired a mythic role as a hero and warrior against heathens. His reception as a saint seems to have spread within the Byzantine empire during wars against the Sasanian Persians and the Muslims in the late 6th and 7th century.<ref>Fourlas 2020.</ref> The motif of the Romanesque equestrian, the mounted figure in the posture of a triumphant Roman emperor, became a visual metaphor in statuary in praise of local benefactors. The name "Constantine" enjoyed renewed popularity in western France in the 11th and 12th centuries.<ref>Seidel, 237–239.</ref> During the [[Fascist Italy|Fascist period in Italy]] in the {{nowrap|20th century}}, parallels between Constantine and [[Mussolini]] became especially popular after the signing of the [[Lateran Pacts]] by the Italian State and the [[Holy See|Catholic Church]] in 1929. Mussolini's perceived role in bringing about the historic agreement was sometimes even explicitly compared to Constantine's Edict of Milan. For example, the archbishop of Milan, Cardinal [[Ildefonso Schuster]], claimed that, after sixteen centuries, a second [[March on Rome]] had occurred and a second 'religious pact' had been established, linking Mussolini to the ''spiriti magni'' of both Constantine and [[Augustus]].<ref>{{cite journal|url=https://doi.org/10.1163/22116257-00802002 |last1=Bettegazzi |first1=Nicolò |last2=Lamers |first2=Han |last3=Reitz-Joosse |first3=Bettina |date=December 2019 |title=Viewing Rome in the Latin Literature of the ''Ventennio Fascista'': Francesco Giammaria's ''Capitolium Novum'' |journal=Fascism |volume=8 |issue=2 |publisher=Brill |page=172 |doi=10.1163/22116257-00802002 |hdl=10852/76385 |hdl-access=free |issn=2211-6249}}</ref>

The [[Niš Constantine the Great Airport]] is named in honour of him. A large cross was planned to be built on a hill overlooking Niš, but the project was cancelled.<ref>{{Cite web |url=https://www.novosti.rs/vesti/srbija.73.html:372896-Nis-Vinik-osta-pusto-brdo |title=Niš: Vinik osta pusto brdo |website=NOVOSTI}}</ref> In 2012, a memorial was erected in Niš in his honour. The ''Commemoration of the Edict of Milan'' was held in Niš in 2013.<ref>{{cite news |url=http://www.b92.net/eng/news/society.php?yyyy=2013&mm=01&dd=17&nav_id=84193 |title=Edict of Milan celebration to begin in Niš |date=17 January 2013}}</ref> The Orthodox Church considers Constantine a saint (Άγιος Κωνσταντίνος, Saint Constantine), having a feast day on 21 May,<ref>Pohlsander, ''Emperor Constantine'', 92–93.</ref> and calls him ''isapostolos'' (ισαπόστολος Κωνσταντίνος)—an [[equal-to-apostles|equal of the Apostles]].<ref>Lieu, "Constantine in Legendary Literature" (CC), 305.</ref>

Constantine is sometimes associated with the [[Religion in politics|religiopolitical]] [[ideology]] known as [[Caesaropapism]], which epitomises the unity of church and state. However, his association with this ideology has been debated.<ref>Averil Cameron, "Introduction", in ''Constantine: History, Historiography, and Legend'', ed. Samuel N. C. Lieu and [[Dominic Montserrat]] (New York: Routledge, 1998), 3; Pohlsander, ''Emperor Constantine'', 91</ref>

=== Historiography ===
[[File:Sir Peter Paul Rubens - Constantius appoints Constantine as his successor - Google Art Project.jpg|thumb|upright=1.2|''[[Constantius Chlorus|Constantius]] appoints Constantine as his successor'' by [[Peter Paul Rubens]], 1622]]
During Constantine's lifetime, [[Praxagoras of Athens]] and [[Libanius]], pagan authors, showered Constantine with praise, presenting him as a paragon of virtue. His nephew and son-in-law Julian the Apostate, however, wrote the satire ''Symposium, or the Saturnalia'' in 361, after the last of his sons died; it denigrated Constantine, calling him inferior to the great pagan emperors, and given over to luxury and greed.<ref>Barnes, ''Constantine and Eusebius'', 272–223.</ref> Following Julian, [[Eunapius]] began – and [[Zosimus (historian)|Zosimus]] continued – a historiographic tradition that blamed Constantine for weakening the empire through his indulgence to the Christians.<ref name="auto">Barnes, ''Constantine and Eusebius'', 273.</ref>

During the [[Middle Ages]], European and Near-East Byzantine writers presented Constantine as an ideal ruler, the standard against which any king or emperor could be measured.<ref name="auto" /> The [[Renaissance]] rediscovery of anti-Constantinian sources prompted a re-evaluation of his career. German humanist [[Johannes Leunclavius]] discovered Zosimus' writings and published a Latin translation in 1576. In its preface, he argues that Zosimus' picture of Constantine offered a more balanced view than that of Eusebius and the Church historians.<ref>[[Johannes Leunclavius]], ''{{lang|la|Apologia pro Zosimo adversus Evagrii, Nicephori Callisti et aliorum acerbas criminationes}}'' (''Defence of Zosimus against the Unjustified Charges of Evagrius, Nicephorus Callistus, and Others'') (Basel, 1576), cited in Barnes, ''Constantine and Eusebius'', 273, and Odahl, 282.</ref> Cardinal [[Caesar Baronius]] criticised Zosimus, favouring Eusebius' account of the Constantinian era. Baronius' ''Life of Constantine'' (1588) presents Constantine as the model of a Christian prince.<ref>Caesar Baronius, ''{{lang|la|[[Annales Ecclesiastici]]}}'' 3 (Antwerp, 1623), cited in Barnes, ''Constantine and Eusebius'', 274, and Odahl, 282.</ref> [[Edward Gibbon]] aimed to unite the two extremes of Constantinian scholarship in his work ''[[The History of the Decline and Fall of the Roman Empire]]'' (1776–1789) by contrasting the portraits presented by Eusebius and Zosimus.<ref>Edward Gibbon, ''The Decline and Fall of the Roman Empire'' Chapter 18, cited in Barnes, ''Constantine and Eusebius'', 274, and Odahl, 282. See also Lenski, "Introduction" (CC), 6–7.</ref> He presents a noble war hero who transforms into an Oriental despot in his old age, "degenerating into a cruel and dissolute monarch".<ref>Gibbon, ''Decline and Fall'', 1.256; David P. Jordan, "Gibbon's 'Age of Constantine' and the Fall of Rome", ''History and Theory'' 8:1 (1969): 71–96.</ref>

Modern interpretations of Constantine's rule begin with [[Jacob Burckhardt]]'s ''The Age of Constantine the Great'' (1853, rev. 1880). Burckhardt's Constantine is a scheming secularist, a politician who manipulates all parties in a quest to secure his own power.<ref>Jacob Burckhardt, ''{{lang|de|Die Zeit Constantins des Grossen}}'' (Basel, 1853; revised edition, Leipzig, 1880), cited in Barnes, ''Constantine and Eusebius'', 274; Lenski, "Introduction" (CC), 7.</ref> [[Henri Grégoire (historian)|Henri Grégoire]] followed Burckhardt's evaluation of Constantine in the 1930s, suggesting that Constantine developed an interest in Christianity only after witnessing its political usefulness. Grégoire was skeptical of the authenticity of Eusebius's ''{{lang|la|Vita}}'', and postulated a pseudo-Eusebius to assume responsibility for the vision and conversion narratives of that work.<ref>Lenski, "Introduction" (CC), 7.</ref> [[Otto Seeck]]'s ''{{lang|de|Geschichte des Untergangs der antiken Welt}}'' (1920–1923) and [[André Piganiol]]'s ''{{lang|fr|L'empereur Constantin}}'' (1932) go against this historiographic tradition. Seeck presents Constantine as a sincere war hero whose ambiguities were the product of his own naïve inconsistency.<ref>Lenski, "Introduction" (CC), 7–8.</ref> Piganiol's Constantine is a philosophical monotheist, a child of his era's religious syncretism.<ref>Barnes, ''Constantine and Eusebius'', 274.</ref> Related histories by [[Arnold Hugh Martin Jones]] (''Constantine and the Conversion of Europe'', 1949) and [[Ramsay MacMullen]] (''Constantine'', 1969) give portraits of a less visionary and more impulsive Constantine.<ref>Lenski, "Introduction" (CC), 8.</ref>

These later accounts were more willing to present Constantine as a genuine convert to Christianity. [[Norman H. Baynes]] began a historiographic tradition with ''Constantine the Great and the Christian Church'' (1929) which presents Constantine as a committed Christian, reinforced by [[Andreas Alföldi]]'s ''The Conversion of Constantine and Pagan Rome'' (1948), and [[Timothy Barnes (classicist)|Timothy Barnes]]'s ''Constantine and Eusebius'' (1981) is the culmination of this trend. Barnes' Constantine experienced a radical conversion which drove him on a personal crusade to convert his empire.<ref>Lenski, "Introduction" (CC), 8–9; Odahl, 283.</ref> Charles Matson Odahl's ''Constantine and the Christian Empire'' (2004) takes much the same tack.<ref>Odahl, 283; Mark Humphries, "Constantine", review of ''Constantine and the Christian Empire'', by Charles Odahl, ''Classical Quarterly'' 56:2 (2006), 449.</ref> In spite of Barnes' work, arguments continue over the strength and depth of Constantine's religious conversion.<ref>Averil Cameron, "Introduction", in ''Constantine: History, Historiography, and Legend'', ed. Samuel N. C. Lieu and [[Dominic Montserrat]] (New York: Routledge, 1998), 3.</ref> Certain themes in this school reached new extremes in T. G. Elliott's ''The Christianity of Constantine the Great'' (1996), which presented Constantine as a committed Christian from early childhood.<ref>Lenski, "Introduction" (CC), 10.</ref> [[Paul Veyne]]'s 2007 work ''{{lang|fr|Quand notre monde est devenu chrétien}}'' holds a similar view which does not speculate on the origin of Constantine's Christian motivation, but presents him as a religious revolutionary who fervently believed that he was meant "to play a providential role in the millenary economy of the salvation of humanity".<ref>[https://archive.today/20120708061334/http://findarticles.com/p/articles/mi_hb6404/is_2_69/ai_n29437350/?tag=content;col1 Quand notre monde est devenu chretien], Fabian E. Udoh, review, ''Theological Studies'', June 2008.</ref> [[Peter Heather]] argues that it is most plausible that Constantine had been a Christian considerably before 312&nbsp;&ndash; possibly even for his entire life&nbsp;&ndash; with the public timeline of events instead reflecting his "coming out" as Christian in stages as doing so became politically viable. As a parallel illustrating the cogency of this interpretation, Heather gestures to the later conversion of Constantine's nephew [[Julian (emperor)|Julian]] from Christianity to Hellenism, after which he practiced in secret for a decade.<ref>Peter Heather, ''Christendom'' (London: Allen Lane, 2022), pp. 11–20.</ref>

=== Donation of Constantine ===
{{Main|Donation of Constantine}}
[[Latin Church|Latin Christians]] considered it inappropriate that Constantine was baptised only on his death bed by an unorthodox bishop, and a [[Acts of Sylvester|legend emerged]] by the early 4th century that [[Pope Sylvester I]] had cured the pagan emperor from leprosy. According to this legend, Constantine was baptised and began the construction of a church in the [[Archbasilica of Saint John Lateran|Lateran Basilica]].<ref>{{cite book |last1=Canella |first1=Tessa |title=Gli Actus Silvestri fra Oriente e Occidente: Storia e diffusione di una leggenda Costantiniana |location=Academia |pages=243–244 |url=https://www.academia.edu/31467158 |access-date=10 May 2021}}</ref><ref>Lieu, "Constantine in Legendary Literature" (CC), 298–301.</ref> The ''Donation of Constantine'' appeared in the 8th century, most likely during the pontificate of [[Pope Stephen II]], in which the freshly converted Constantine gives "the city of Rome and all the provinces, districts, and cities of Italy and the Western regions" to Sylvester and his successors.<ref>''Constitutum Constantini'' 17, qtd. in Lieu, "Constantine in Legendary Literature" (CC), 301–303.</ref> In the [[High Middle Ages]],<ref>Gregory, ''A History of Byzantium'', 49.</ref><ref>Van Dam, ''Remembering Constantine at the Milvian Bridge'', 30.</ref> this document was used and accepted as the basis for the pope's [[Temporal power of the Holy See|temporal power]], though it was denounced as a forgery by Emperor [[Otto III, Holy Roman Emperor|Otto III]]<ref>Henry Charles Lea, "The 'Donation of Constantine'". ''The English Historical Review'' 10: 37 (1895), 86–87.</ref> and lamented as the root of papal worldliness by [[Dante Alighieri]].<ref>''Inferno'' 19.115; ''Paradisio'' 20.55; cf. ''De Monarchia'' 3.10.</ref> Philologist and Catholic priest [[Lorenzo Valla]] proved in 1440 that the document was indeed a forgery.<ref>Fubini, 79–86; Lenski, "Introduction" (CC), 6.</ref>

=== Geoffrey of Monmouth's ''Historia'' ===
During the medieval period, [[Celtic Britons|Britons]] regarded Constantine as a king of their own people, particularly associating him with [[Segontium|Caernarfon]] in [[Kingdom of Gwynedd|Gwynedd]]. While some of this is owed to his fame and his proclamation as emperor in [[Roman Britain|Britain]], there was also confusion of his family with [[Magnus Maximus]]'s supposed wife [[Saint Elen|Elen]] and her son, another Constantine {{nowrap|({{langx|cy|Custennin}})}}. In the 12th century [[Henry of Huntingdon]] included a passage in his ''Historia Anglorum'' that the Emperor Constantine's mother was a Briton, making her the daughter of [[Coel Hen|King Cole]] of [[Colchester]].<ref>Henry of Huntingdon, ''Historia Anglorum'', Book I, ch. 37.</ref> [[Geoffrey of Monmouth]] expanded this story in his highly fictionalised {{Lang|la|Historia Regum Britanniae}}, an account of the supposed [[list of legendary kings of Britain|Kings of Britain]] from their [[Troy|Trojan]] origins to the [[Anglo-Saxon settlement of Britain|Anglo-Saxon invasion]].<ref name="Greenway">{{cite book |last1=Greenway |first1=Diana (Ed.) |author2=Henry of Huntingdon |title=Historia Anglorum: The History of the English People |publisher=Oxford University Press |year=1996 |isbn=978-0-19-822224-8 |page=civ}}</ref> According to Geoffrey, Cole was King of the Britons when Constantius, here a senator, came to Britain. Afraid of the Romans, Cole submits to Roman law so long as he retains his kingship. However, he dies only a month later, and Constantius takes the throne himself, marrying Cole's daughter Helena. They have their son Constantine, who succeeds his father as King of Britain before becoming Roman emperor.

Historically, this series of events is extremely improbable. Constantius had already left Helena by the time he left for Britain.{{sfnm|1a1=Barnes|1y=1981|1p=3|2a1=Elliott|2y=1996|2p=20|3a1=Lenski et al.|3pp=59–60|4a1=Odahl|4y=2001|4pp=47, 299|5a1=Pohlsander|5y=2004a|5p=14}} Additionally, no earlier source mentions that Helena was born in Britain, let alone that she was a princess. Henry's source for the story is unknown, though it may have been a lost hagiography of Helena.<ref name="Greenway" />

==Family tree==
{{see also|Constantinian dynasty}}

{{Constantinian dynasty family tree}}

{{Chart top|width=100%|collapsed=auto}}
Emperors are shown with a rounded-corner border with their dates as [[Augusti]], names with a thicker border appear in both sections

'''1: Constantine's parents and half-siblings'''
{{Tree chart/start|align=center}}
{{tree chart| | | | | | |CGOTH|CGOTH={{ubl|[[Claudius Gothicus]]|268–270|''fabricated ancestry''}}|boxstyle_CGOTH=border:2px solid; border-radius:1em}}
{{tree chart| | | | | | | |Q|}}
{{tree chart| | |HELEN|y|CCHLO|y|THEO1|HELEN=[[Helena, mother of Constantine I|Julia Helena]]|boxstyle_HELEN=border:2px solid|CCHLO={{ubl|[[Constantius Chlorus|Constantius I]]|305–306}}|boxstyle_CCHLO=border:2px solid; border-radius:1em|THEO1=[[Flavia Maximiana Theodora|Maximiana Theodora]]}}
{{tree chart| | | | | |!| | | |)|-|v|-|v|-|-|-|v|-|-|-|-|-|v|-|.| | | | | }}
{{tree chart| | | | |CONST| |FLAVD|!|HANN1| |CONS2|y|LICI1|!|ANAST|~|BASSI|CONST={{ubl|'''Constantine I'''|306–337}}|boxstyle_CONST=border:3px solid; border-radius:1em|FLAVD=[[Flavius Dalmatius]]|HANN1=Hannibalianus|CONS2=[[Flavia Julia Constantia]]|LICI1={{ubl|[[Licinius]]|308–324}}|boxstyle_LICI1=border:2px solid; border-radius:1em|ANAST=[[Anastasia (sister of Constantine I)|Anastasia]]|BASSI=[[Bassianus (executed by Constantine)|Bassianus]]}}
{{tree chart| |,|-|-|-|-|-|-|-|'| |!| | | | | | | |!| | | |!}}
{{tree chart| |!| | | | |GALL1|y|JULIC|y|BASIL| |LICI2| |EUTR2|y|NEPO1|GALL1=[[Galla (wife of Julius Constantius)|Galla]]|JULIC=[[Julius Constantius]]|BASIL=[[Basilina]]|LICI2=[[Licinius II]]|EUTR2=[[Eutropia (sister of Constantine I)|Eutropia]]|NEPO1=[[Viria gens|Virius Nepotianus]]}}
{{tree chart| |!| | | | | | | |!| | | |!| | | | | | | | | | | |!}}
{{tree chart|HANN2|~|CONS6|~|GALLU| |JULIA|~|HELE2| | | | | |NEPO2|HANN2=[[Hannibalianus]]|boxstyle_HANN2=border:3px solid|CONS6=[[Constantina]]|boxstyle_CONS6=border:3px solid|GALLU=[[Constantius Gallus]]|boxstyle_GALLU=border:3px solid|JULIA={{ubl|[[Julian (emperor)|Julian]]|360–363}}|boxstyle_JULIA=border:3px solid; border-radius:1em|HELE2=[[Helena (wife of Julian)|Helena]]|boxstyle_HELE2=border:3px solid|NEPO2=[[Nepotianus]]}}
{{tree chart/end}}
{{break}}
'''2: Constantine's children'''
{{Tree chart/start|align=center}}
{{tree chart|MINER|y|CONST|y|FAUS1|MINER=[[Minervina]]|CONST={{ubl|'''Constantine I'''|306–337}}|boxstyle_CONST=border:3px solid; border-radius:1em|FAUS1=[[Fausta]]}}
{{tree chart| | | |!| | | |)|-|v|-|v|-|v|-|-|-|-|-|.|}}
{{tree chart| | |CRISP| |CONS3|!|CONS5|!|HANN2|~|CONS6|~|GALLU|CRISP=[[Crispus]]|CONS3={{ubl|[[Constantine II (emperor)|Constantine II]]|337–340}}|boxstyle_CONS3=border:2px solid; border-radius:1em|CONS5={{ubl|[[Constans]]|337–350}}|boxstyle_CONS5=border:2px solid; border-radius:1em|HANN2=[[Hannibalianus]]|boxstyle_HANN2=border:3px solid|CONS6=[[Constantina]]|boxstyle_CONS6=border:3px solid|GALLU=[[Constantius Gallus]]|boxstyle_GALLU=border:3px solid}}
{{tree chart| | | | | | | | | |!| | | |!}}
{{tree chart| | | | |FAUS2|y|CONS4| |HELE2|~|JULIA|FAUS2=[[Faustina (wife of Constantius II)|Faustina]]|CONS4={{ubl|[[Constantius II]]|337–361}}|boxstyle_CONS4=border:2px solid; border-radius:1em|JULIA={{ubl|[[Julian (emperor)|Julian]]|360–363}}|boxstyle_JULIA=border:3px solid;  border-radius:1em|HELE2=[[Helena (wife of Julian)|Helena]]|boxstyle_HELE2=border:3px solid}}
{{tree chart| | | | | | | |!}}
{{tree chart| | |GRATI|~|CONS7|GRATI={{ubl|[[Gratian]]|367–383}}|boxstyle_GRATI=border:2px solid; border-radius:1em|CONS7=[[Constantia (wife of Gratian)|Constantia]]}}
{{Tree chart/end}}
{{Chart bottom}}

== See also ==
{{Portal|Byzantine Empire|Saints}}
* [[Bronze colossus of Constantine]]
* [[Colossus of Constantine]]
* [[Fifty Bibles of Constantine]]
* [[German and Sarmatian campaigns of Constantine]]
* ''[[Life of Constantine]]''
* [[List of Byzantine emperors]]
* [[List of people known as the Great|List of people known as the great]]

== Notes ==
{{Notelist}}


== Citations ==
{{Reflist|26em}}

=== Bibliography ===
====Ancient sources====
{{refbegin|40em}}
*[[Athanasius]] of Alexandria. ''Apologia contra Arianos'' (''Defence against the Arians'') {{Circa|349}}.
**Atkinson, M., and Archibald Robertson, trans. ''Apologia Contra Arianos''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 4. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1892. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2808.htm New Advent]. Retrieved 14 August 2009.
*Athanasius of Alexandria ''Epistola de Decretis Nicaenae Synodi'' (''Letter on the Decrees of the Council of Nicaea'') {{Circa|352}}.
**Newman, John Henry, trans. ''De Decretis''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 4. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1892. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2809.htm New Advent]. Retrieved 28 September 2009.
*Athanasius of Alexandria ''Historia Arianorum'' (''History of the Arians'') {{Circa|357}}.
**Atkinson, M., and Archibald Robertson, trans. ''Historia Arianorum''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 4. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1892. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2815.htm New Advent]. Retrieved 14 August 2009.
*[[Aurelius Victor|Sextus Aurelius Victor]], ''Liber de Caesaribus'' (''Book on the Caesars'') {{Circa|361}}.
*''Codex Theodosianus'' (''Theodosian Code'') 439.
**Mommsen, T. and Paul M. Meyer, eds. ''Theodosiani libri XVI cum Constitutionibus Sirmondianis et Leges novellae ad Theodosianum pertinentes''<sup>2</sup> (in Latin). Berlin: Weidmann, [1905] 1954. Compiled by Nicholas Palmer, revised by [[Tony Honoré]] for Oxford Text Archive, 1984. Prepared for online use by R.W.B. Salway, 1999. Preface, books 1–8. Online at [https://web.archive.org/web/20090826174516/http://www.ucl.ac.uk/history2/volterra/texts/cthinfo.htm University College London] and the [https://web.archive.org/web/20070312033154/http://webu2.upmf-grenoble.fr/Haiti/Cours/Ak/Constitutiones/codtheod.html University of Grenoble]. Retrieved 25 August 2009.
**Unknown edition (in Latin). Online at [http://ancientrome.ru/ius/library/codex/theod/ AncientRome.ru]. Retrieved 15 August 2009.
*''Codex Justinianeus'' (''Justinianic Code'' or ''Code of Justinian'').
**Scott, Samuel P., trans. ''The Code of Justinian'', in ''The Civil Law''. 17 vols. 1932. Online at the [http://www.constitution.org/sps/sps.htm Constitution Society]. Retrieved 14 August 2009.
** {{cite book |editor1-last=Krueger |editor1-first=Paul |date=1954 |title=Codex Justinianus |language=la |url=http://web.upmf-grenoble.fr/Haiti/Cours/Ak/ |archive-url=https://web.archive.org/web/20120831060912/http://web.upmf-grenoble.fr/Haiti/Cours/Ak/ |url-status=dead |archive-date=31 August 2012 |location=Berlin |publisher=Apud Weidmannos |via=the Internet Archive |access-date=28 September 2009}}
* Constantine the Great, ''Speech to the Assembly of the Saints''.
** [[Klaus Martin Girardet|Girardet, Klaus Martin]] (2013). ''Konstantin, Rede an die Versammlung der Heiligen – Oratio ad sanctorum coetum. Einleitung, griechischer Text, Übersetzung, Kommentar.'' [[Fontes Christiani]] vol. 55. Freiburg: Herder, {{ISBN|978-3-451-30957-1}}.
* Constantine the Great, ''Letters''
** [[Pierre Maraval|Maraval, Pierre]] (2010). ''Constantin, Lettres et discours.'' La roue à livres, volume 57. Paris: Les Belles Lettres, {{ISBN|978-2-251-33958-0}}.
*''[[Epitome de Caesaribus]]'' (''Epitome on the Caesars'') {{Circa|395}}.
**Banchich, Thomas M., trans. ''A Booklet About the Style of Life and the Manners of the Imperatores''. ''Canisius College Translated Texts'' 1. Buffalo, NY: Canisius College, 2009. Online at [http://www.roman-emperors.org/epitome.htm De Imperatoribus Romanis]. Retrieved 15 August 2009.
*{{Lang|la|[[De Rebus Bellicis]]}} (''On Military Matters'') fourth/fifth century.
*[[Eunapius]], ''History from Dexippus'' first edition {{Circa|390}}, second edition {{Circa|415}}. [Fragmentary]
*[[Eusebius of Caesarea]].
**''Historia Ecclesiastica'' (''Church History'') first seven books {{Circa|300}}, eighth and ninth book {{Circa|313}}, tenth book {{Circa|315}}, epilogue {{Circa|325}}.
***Williamson, G.A., trans. ''Church History''. London: Penguin, 1989. {{ISBN|0-14-044535-8}}
***McGiffert, Arthur Cushman, trans. ''Church History''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 1. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1890. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2501.htm New Advent]. Retrieved 28 September 2009.
**''Oratio de Laudibus Constantini'' (''Oration in Praise of Constantine'', sometimes the ''Tricennial Oration'') 336.
***Richardson, Ernest Cushing, trans. ''Oration in Praise of Constantine''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 1. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1890. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2504.htm New Advent]. Retrieved 16 August 2009.
**''Vita Constantini'' (''The Life of the Blessed Emperor Constantine'') {{Circa|336}}–339.
***Richardson, Ernest Cushing, trans. ''Life of Constantine''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 1. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1890. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2502.htm New Advent]. Retrieved 9 June 2009.
***[http://www.evolpub.com/CRE/CREseries.html#CRE8 ''Life of the Blessed Emperor Constantine'']. 2009. Reprint of Bagster edition [1845]. Evolution Publishing. {{ISBN|978-1-889758-93-0}}.
***Cameron, Averil and Stuart Hall, trans. ''[http://archive.eclass.uth.gr/eclass/modules/document/file.php/SEAD260/%CE%95%CF%85%CF%83%CE%AD%CE%B2%CE%B9%CE%BF%CF%82%2C%20Life%20of%20Constantine%20%28trans.%20Averil%20Cameron%20-%20Stuart%20Hall%29.pdf Life of Constantine]''. 1999. Oxford University Press. {{ISBN|0-19-814924-7}}.
*[[Eutropius (historian)|Eutropius]], ''Breviarium ab Urbe Condita'' (''Abbreviated History from the City's Founding'') {{Circa|369}}.
**Watson, John Henry, trans. ''Justin, Cornelius Nepos and Eutropius''. London: George Bell & Sons, 1886. Online at [http://www.tertullian.org/fathers/eutropius_breviarium_2_text.htm Tertullian]. Retrieved 28 September 2009.
*[[Festus (historian)|Rufus Festus]], ''Breviarium Festi'' (''The Abbreviated History of Festus'') {{Circa|370}}.
**Banchich, Thomas M., and Jennifer A. Meka, trans. ''Breviarium of the Accomplishments of the Roman People''. ''Canisius College Translated Texts'' 2. Buffalo, NY: Canisius College, 2001. Online at [http://www.roman-emperors.org/festus.htm De Imperatoribus Romanis]. Retrieved 15 August 2009.
*[[Jerome]], ''[[Chronicon (Jerome)|Chronicon]]'' (''Chronicle'') {{Circa|380}}.
**Pearse, Roger, ''et al.''., trans. ''The Chronicle of St. Jerome'', in ''Early Church Fathers: Additional Texts''. Tertullian, 2005. Online at [http://www.tertullian.org/fathers/jerome_chronicle_00_eintro.htm Tertullian]. Retrieved 14 August 2009.
*[[Jordanes]], ''[[Getica|De origine actibusque Getarum]]'' [''Getica''] (''The Origin and Deeds of the Goths'') {{Circa|551}}.
**[[Charles Christopher Mierow|Mierow, Charles C.]], trans. ''The Origins and Deeds of the Goths''. Princeton: Princeton University Press, 1915.
***Online at the [https://www.ucalgary.ca/~vandersp/Courses/texts/jordgeti.html University of Calgary]. Retrieved 28 September 2009.
***''The Gothic History of Jordanes''. 2006. Reprint of 1915 edition. Evolution Publishing. {{ISBN|978-1-889758-77-0}}. [http://www.evolpub.com/CRE/CREseries.html#CRE2 The Christian Roman Empire series]
*[[Lactantius]], ''[[De mortibus persecutorum]]'' (''On the Deaths of the Persecutors'') {{Circa|313–315}}.
**Fletcher, William, trans. ''Of the Manner in Which the Persecutors Died''. From ''Ante-Nicene Fathers'', Vol. 7. Edited by Alexander Roberts, James Donaldson, and A. Cleveland Coxe. Buffalo, NY: Christian Literature Publishing Co., 1886. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/0705.htm New Advent]. Retrieved 9 June 2009.
*[[Libanius]], ''[https://opengreekandlatin.github.io/libanius-dev/ Orationes]'' (''Orations'') {{Circa|362}}–365.
*[[Saint Optatus|Optatus]], ''Libri VII de Schismate Donatistarum'' (''Seven Books on the Schism of the Donatists'') first edition {{Circa|365}}–367, second edition {{Circa|385}}.
**Vassall-Phillips, O.R., trans. ''The Work of St. Optatus Against the Donatists''. London: Longmans, Green, & Co., 1917. Transcribed at The Tertullian Project by Roger Pearse, 2006. Online at [http://www.tertullian.org/fathers/optatus_00_intro.htm Tertullian]. Retrieved 9 June 2009.
**{{cite book |author=Optatus |editor1-last=Edwards |editor1-first=Mark |year=1997 |title=Optatus: Against the Donatists |url=https://archive.org/details/optatusagainstdo0000opta |url-access=registration |translator-last=Edwards |translator-first=Mark |doi=10.3828/978-0-85323-752-5 |doi-broken-date=1 November 2024 |isbn=978-0-85323-752-5}}
*''Origo Constantini Imperiatoris'' (''The Lineage of the Emperor Constantine'') {{Circa|340}}–390.
**Rolfe, J.C., trans. ''Excerpta Valesiana'', in vol. 3 of Rolfe's translation of Ammianus Marcellinus' ''History''. Loeb ed. London: Heinemann, 1952. Online at [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Excerpta_Valesiana/1*.html LacusCurtius]. Retrieved 16 August 2009.
*[[Paulus Orosius|Orosius]], ''[http://attalus.org/info/orosius.html Historiarum Adversum Paganos Libri VII]'' (''Seven Books of History Against the Pagans'') {{Circa|417}}.
*''[[Panegyrici Latini|XII Panegyrici Latini]]'' (''Twelve Latin Panegyircs'') relevant panegyrics dated 289, 291, 297, 298, 307, 310, 311, 313 and 321.
*[[Philostorgius]], ''Historia Ecclesiastica'' (''Church History'') {{Circa|433}}.
**Walford, Edward, trans. ''Epitome of the Ecclesiastical History of Philostorgius, Compiled by Photius, Patriarch of Constantinople''. London: Henry G. Bohn, 1855. Online at [http://www.tertullian.org/fathers/philostorgius.htm Tertullian]. Retrieved 15 August 2009.
*[[Praxagoras of Athens]], ''Historia'' (''History of Constantine the Great'') {{Circa|337}}. [Fragmentary]
*[[Socrates of Constantinople]] (Scholasticus), ''Historia Ecclesiastica'' (''Church History'') {{Circa|443}}.
**Zenos, A.C., trans. ''Ecclesiastical History''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 2. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1890. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2601.htm New Advent]. Retrieved 14 August 2009.
*[[Sozomen]], ''Historia Ecclesiastica'' (''Church History'') {{Circa|445}}.
**[[Chester D. Hartranft|Hartranft, Chester D.]] ''Ecclesiastical History''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 2. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1890. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2602.htm New Advent]. Retrieved 15 August 2009.
*[[Theodoret]], ''Historia Ecclesiastica'' (''Church History'') {{Circa|448}}.
**Jackson, Blomfield, trans. ''Ecclesiastical History''. From ''Nicene and Post-Nicene Fathers'', Second Series, Vol. 3. Edited by Philip Schaff and Henry Wace. Buffalo, NY: Christian Literature Publishing Co., 1892. Revised and edited for New Advent by Kevin Knight. Online at [http://www.newadvent.org/fathers/2702.htm New Advent]. Retrieved 15 August 2009.
*[[Zosimus (historian)|Zosimus]], ''Historia Nova'' (''New History'') {{Circa|500}}.
**Unknown, trans. ''The History of Count Zosimus''. London: Green and Champlin, 1814. Online at [http://www.tertullian.org/fathers/zosimus00_intro.htm Tertullian]. Retrieved 15 August 2009.<!-- {{refn|This translation is not very good. The pagination is broken in several places, there are many typographical errors (including several replacements of "Julian" with "Jovian" and "Constantine" with "Constantius"). It is nonetheless the only translation of the ''Historia Nova'' in the public domain.<ref>Roger Pearse, "[http://www.tertullian.org/fathers/zosimus00_intro.htm Preface to the online edition of Zosimus' ''New History'']". 19 November 2002, rev. 20 August 2003. Retrieved 15 August 2009.</ref>|group=notes}}
<ref>This list of primary sources is based principally on the summary in Odahl, 2–11 and further lists in Odahl, 372–76. See also Bruno Bleckmann, "Sources for the History of Constantine" (CC), "Sources for the History of Constantine", in ''The Cambridge Companion to the Age of Constantine'', trans. Noel Lenski, ed. Noel Lenski (New York: Cambridge University Press, 2006), 14–31; and Noel Lenski, ed. ''The Cambridge Companion to the Age of Constantine'' (New York: Cambridge University Press, 2006), 411–17.</ref> -->
{{refend}}

====Modern sources====
{{refbegin|40em|indent=y}}
*{{Cite book |last=Alföldi |first=Andreas |url=https://archive.org/details/conversionofcons0000alfl |title=The conversion of Constantine and pagan Rome |date=1948 |publisher=Clarendon Press |isbn=9780198143567 |translator-last=Harold Mattingly}}
*{{cite book |last=Anderson |first=Perry |author-link=Perry Anderson |date=2013 |orig-year=1974 |title=Passages from Antiquity to Feudalism |publisher=Verso Books |isbn=9781781680087 |url=https://books.google.com/books?id=NE9qw3_yCRgC}}
*{{cite journal |doi=10.1093/jaarel/XXXII.1.1 |title=Church and State Relations: The Changes Wrought by Constantine |journal=Journal of the American Academy of Religion |pages=1–7 |year=1964 |last1=Armstrong |first1=Gregory T. |volume=XXXII}}
*{{cite journal |doi=10.2307/988835 |jstor=988835 |title=Constantine's Churches: Symbol and Structure |journal=Journal of the Society of Architectural Historians |volume=33 |issue=1 |pages=5–16 |year=1974 |last1=Armstrong |first1=Gregory T.}}
*{{cite journal |doi=10.2307/299163 |jstor=299163 |title=Lactantius and Constantine |journal=Journal of Roman Studies |volume=63 |pages=29–46 |year=1973 |last1=Barnes |first1=T. D. |s2cid=163051414}}
*{{cite book |last=Barnes |first=Timothy D. |author-link=Timothy Barnes (classicist) |title=Constantine and Eusebius |url=https://books.google.com/books?id=LGDjJK-JeSwC |year=1981 |publisher=Harvard University Press |location=Cambridge, MA |isbn=978-0-674-16531-1}}
*{{cite book |doi=10.4159/harvard.9780674280670 |title=The New Empire of Diocletian and Constantine |year=1982 |last1=Barnes |first1=Timothy D. |s2cid=162343436 |isbn=9780674280670}}
*{{cite journal |doi=10.2307/300656 |jstor=300656 |title=Constantine and the Christians of Persia |journal=Journal of Roman Studies |volume=75 |pages=126–136 |year=1985 |last1=Barnes |first1=T. D. |s2cid=162744718}}
*{{cite book |last=Barnes |year=2011 |first=Timothy |title=Constantine: Dynasty, Religion and Power in the Later Roman Empire |publisher=Wiley-Blackwell |place=Oxford |isbn=978-1-405-11727-2}}
*{{Cite book |url=https://books.google.com/books?id=dGzDDwAAQBAJ&pg=PA530 |title=Armenia between Byzantium and the Orient|date=2019|publisher=BRILL |isbn=978-90-04-39774-3 |last=Bernard |first=Outtier |pages=230–580|display-authors=etal}}
*{{cite book |doi=10.1017/CHOL9780521301992.004 |chapter=Diocletian and the first tetrarchy, a.d. 284–305 |title=The Cambridge Ancient History |pages=67–89 |year=2005 |last1=Bowman |first1=Alan K. |isbn=9781139053921}}
*{{cite book |doi=10.1017/CHOL9780521301992.005 |chapter=The Reign of Constantine, a.d. 306–337 |title=[[The Cambridge Ancient History]] | volume=12 |pages=90–109 |year=2005 |last1=Cameron |first1=Averil |isbn=9781139053921 |chapter-url=https://books.google.com/books?id=MNSyT_PuYVMC&pg=PA90}}
*{{cite book |year=1999 |last1=Carrié |first1=Jean-Michel |last2=Rouselle |first2=Aline |title=L'Empire Romain en mutation- des Sévères à Constantin, 192–337 |publisher=Seuil |place=Paris |isbn=2-02-025819-6}}
*{{cite book |year=2003 |last1=Christol |first1=Michel |author1-link=Michel Christol |last2=Nony |first2=D. |title=Rome et son Empire |publisher=Hachette |place=Paris |isbn=2-02-025819-6}}
*{{cite book |year=1996 |last1=Corcoran |first1=Simon |author-link=Simon Corcoran |title=The Empire of the Tetrarchs: Imperial Pronouncements and Government, AD 284–324 |publisher=Clarendon Press |place=Oxford |isbn=0-19-815304-X}}
*{{cite book |last=Curran |first=John |title=Pagan City and Christian Capital |location=Oxford |publisher=Clarendon Press |year=2000 |edition=Hardcover |isbn=0-19-815278-7}} Paperback {{ISBN|0-19-925420-6}}
*{{cite book |last=Dagron |first=Gilbert |title=Naissance d'une Capitale: Constantinople et ses institutions de 330 a 451 |location=Paris |publisher=Presses Universitaires de France |year=1984 |isbn=2-13-038902-3 |url=https://gallica.bnf.fr/ark:/12148/bpt6k3403692s/f9.item.texteImage}}
*{{cite book |last=Digeser |first=Elizabeth DePalma |author-link=Elizabeth DePalma Digeser |title=The Making of A Christian Empire: Lactantius and Rome |location=London |publisher=Cornell University Press |year=2000 |isbn=0-8014-3594-3}}
*{{Cite book |last=Doležal |first=Stanislav |url=https://books.google.com/books?id=4hVuEAAAQBAJ&pg=PA221 |title=The Reign of Constantine, 306–337: Continuity and Change in the Late Roman Empire |date=2022 |publisher=Springer Nature |isbn=978-3-030-97464-0 }}
*{{cite journal |doi=10.2307/2849245 |jstor=2849245 |title=Education in the Christian Roman Empire: Christian and Pagan Theories under Constantine and His Successors |journal=Speculum |volume=32 |issue=1 |pages=48–61 |year=1957 |last1=Downey |first1=Glanville |s2cid=161904593}}
*{{cite journal |doi=10.1086/367077 |title=What Eusebius Knew: The Genesis of the "Vita Constantini" |journal=Classical Philology |volume=83 |pages=20–38 |year=1988 |last1=Drake |first1=H. A. |s2cid=162370910}} 
*{{cite journal |doi=10.2307/3168653 |jstor=3168653 |title=Constantine and Consensus |journal=Church History |volume=64 |issue=1 |pages=1–15 |year=1995 |last1=Drake |first1=H. A. |s2cid=163129848}}
*{{cite journal |doi=10.1093/past/153.1.3 |title=Lambs into Lions: Explaining Early Christian Intolerance |journal=Past & Present |issue=153 |pages=3–36 |year=1996 |last1=Drake |first1=H. A.}}
*{{cite book |last=Drake |first=H. A. |title=Constantine and the Bishops: The Politics of Intolerance |location=Baltimore |publisher=Johns Hopkins University Press |year=2000 |isbn=0-8018-6218-3}}
*{{cite journal |doi=10.2307/1088714 |jstor=1088714 |title=Constantine's Conversion: Do We Really Need It? |journal=Phoenix |volume=41 |issue=4 |pages=420–438 |year=1987 |last1=Elliott |first1=T. G.}}
*{{cite journal |doi=10.2307/1088553 |jstor=1088553 |title=Eusebian Frauds in the "Vita Constantini" |journal=Phoenix |volume=45 |issue=2 |pages=162–171 |year=1991 |last1=Elliott |first1=T. G.}}
*{{cite book |last=Elliott |first=T. G. |title=The Christianity of Constantine the Great |location=Scranton, PA |publisher=University of Scranton Press |year=1996 |isbn=0-940866-59-5}}
*{{cite journal |doi=10.2307/301456 |jstor=301456 |title=Between Pagans and Christians |journal=Journal of Roman Studies |volume=78 |pages=173–182 |year=1988 |last1=Fowden |first1=Garth |s2cid=163374397}}
*{{cite journal |doi=10.2307/300874 |jstor=300874 |title=The Last Days of Constantine: Oppositional Versions and their Influence |journal=Journal of Roman Studies |volume=84 |pages=146–170 |year=1994 |last1=Fowden |first1=Garth |s2cid=161959828}}
*{{cite journal |doi=10.1353/jhi.1996.0004 |title=Humanism and Truth: Valla Writes Against the Donation of Constantine |journal=Journal of the History of Ideas |volume=57 |pages=79–86 |year=1996 |last1=Fubini |first1=Riccardo |s2cid=170927536}}
*{{cite book |last=Gibbon |first=Edward |author-link=Edward Gibbon |date=1952 |orig-year=1789 |title=[[Decline and Fall of the Roman Empire]] |publisher=[[Encyclopædia Britannica, Inc.]] in 2 volumes}}
*{{cite book |last=Goldsworthy |first=Adrian |author-link=Adrian Goldsworthy |date=2009 |title=How Rome Fell |publisher=Yale University Press |url=https://archive.org/details/howromefelldeath0000gold |isbn=978-0-300-13719-4}}
*{{cite journal |doi=10.1086/486406 |title=Religion and Politics at the Council at Nicaea |journal=The Journal of Religion |volume=55 |pages=1–12 |year=1975 |last1=Grant |first1=Robert M. |s2cid=170410226}}
*{{cite journal |doi=10.2307/1087057 |jstor=1087057 |title=The Execution of Crispus |journal=Phoenix |volume=20 |issue=4 |pages=325–331 |year=1966 |last1=Guthrie |first1=Patrick}}
*{{cite journal |doi=10.2307/3163949 |jstor=3163949 |title=Christians and the Roman Army A.D. 173–337 |journal=Church History |volume=43 |issue=2 |pages=149–163 |year=1974 |last1=Helgeland |first1=John |s2cid=162376477}}
*{{cite book |last=Jones |year=1971 |first=A.H.M. |author2=J.R. Martindale |author3=J. Morris |title=Prosopography of the Later Roman Empire |volume=1 |publisher=Cambridge University Press |isbn=0-521-07233-6 |url=https://archive.org/details/prosopography-later-roman-empire/PLRE-I |name-list-style=amp |author-link=A. H. M. Jones |author-link2=John Robert Martindale |author-link3=John Morris (historian) |ref={{sfnref|Jones|Martindale|Morris}}}}
*{{cite journal |doi=10.2307/2504190 |jstor=2504190 |title=Gibbon's "Age of Constantine" and the Fall of Rome |journal=History and Theory |volume=8 |issue=1 |pages=71–96 |year=1969 |last1=Jordan |first1=David P.}}
*{{Cite book |date=1991 |url=https://archive.org/details/odb_20210521 |title=Oxford Dictionary of Byzantium |editor-last=Kazhdan |editor-first=Alexander P. |editor-link=Alexander Kazhdan |publisher=Oxford University Press |isbn=978-0-19-504652-6}}
*{{cite book |last=Jones |first=A.H.M. |author-link=Arnold Hugh Martin Jones |title=Constantine and the Conversion of Europe |location=Buffalo |publisher=University of Toronto Press |year=1978 |isbn=9780802063694 |orig-year=1948 |url=https://archive.org/details/constantineconve00jone_0}}
*{{cite book |last=Lenski |first=Noel |display-authors=etal|ref={{SfnRef|Lenski et al.}} |title=The Cambridge Companion to the Age of Constantine |location=New York |publisher=Cambridge University Press |year=2006 |url=https://books.google.com/books?id=cfRTip1qBJcC&pg=PA1 |isbn=9780521521574}}
*{{cite book |last1=Lieu |first1=Samuel N.C. |author-link=Samuel N. C. Lieu |last2=Montserrat |first2=Dominic |author2-link=Dominic Montserrat |title=From Constantine to Julian: Pagan and Byzantine Views; A Source History |location=New York |publisher=Routledge |year=1996 |isbn=9780415093354 |url=https://books.google.com/books?id=XnTNWtBmhv8C}}
*{{cite journal |doi=10.1086/449431 |title=Lactantius and the Succession to Diocletian |journal=Classical Philology |volume=94 |issue=2 |pages=198–209 |year=1999 |last1=MacKay |first1=Christopher S. |s2cid=161141658}}
*{{cite book |last=MacMullen |first=Ramsay |author-link=Ramsay MacMullen |title=Constantine |location=New York |publisher=Dial Press |year=1969 |isbn=0-7099-4685-6}}
*[[David Mattingly (author)|Mattingly, David]]. ''An Imperial Possession: Britain in the Roman Empire''. London: Penguin, 2007. {{ISBN|978-0-14-014822-0}}
*{{citation|last=McLay |first=Denis |title=An Examination of the Role of Ossius, Bishop of Córdoba, in the Arian Controversy |journal=Dissertation – Durham University |url=https://www.academia.edu/65018532|year=2015}}
*{{cite journal |doi=10.1163/157007200X00189 |title=Constantine's Vision of the Ecross |journal=Vigiliae Christianae |volume=54 |issue=3 |pages=309–323 |year=2000 |last1=Nicholson |first1=Oliver}}
*{{cite book |last1=Odahl |first1=Charles M.|title=Constantine and the Christian Empire |date=2001 |publisher=Routledge |isbn=978-0-415-17485-5 |location=London|url=https://books.google.com/books?id=770uCgAAQBAJ}}
*{{cite journal |doi=10.1093/ehr/XXIV.XCIII.1 |title=The Campaign against Paganism A.D. 824 |journal=The English Historical Review |pages=1–17 |year=1909 |last1=Pears |first1=Edwin |volume=XXIV |issue=XCIII}}
*{{cite journal |doi=10.3406/etnor.1984.2597 |title=La céramique normande |journal=Études Normandes |volume=33 |issue=2 |pages=79–106 |year=1984 |last1=Vaudour |first1=Catherine}}
*{{cite book |last=Pohlsander |first=Hans |title=The Emperor Constantine |location=London & New York |publisher=Routledge |year=2004a |isbn=0-415-31937-4 |url=https://books.google.com/books?id=-DCEKDw7I7cC}} Paperback {{ISBN|0-415-31938-2}}
*{{cite web |last=Pohlsander|first=Hans|year=2004b|url=http://www.roman-emperors.org/conniei.htm |title=Constantine I (306–337)|website=[[De Imperatoribus Romanis]]|archive-url=https://web.archive.org/web/20220402075317/http://www.roman-emperors.org/conniei.htm |archive-date=2 April 2022 }}
*{{cite book |last=Potter |first=David S. |title=The Roman Empire at Bay: AD 180–395 |location=New York |publisher=Routledge |year=2004 |edition=Hardcover |isbn=0-415-10057-7 |url=https://books.google.com/books?id=Da6U4NaBMZAC}} Paperback {{ISBN|0-415-10058-5}}
*{{cite book |doi=10.1093/acprof:oso/9780199249183.001.0001 |title=Layers of Loyalty in Latin Panegyric |year=2002 |last1=Rees |first1=Roger |isbn=9780199249183}}
*{{cite journal |doi=10.1017/S0009838800040611 |title=The Metamorphosis of Constantine |journal=The Classical Quarterly |volume=39 |pages=233–246 |year=1989 |last1=Rodgers |first1=Barbara Saylor |s2cid=170720156}}
*Scheidel, Walter. "The Monetary Systems of the Han and Roman Empires". In Scheidel, ed., ''Rome and China: Comparative Perspectives on Ancient World Empires''. Oxford: Oxford University Press, 2010, {{ISBN|978-0-19-975835-7}}
*{{cite journal |doi=10.2307/766771 |jstor=766771 |title=Constantine 'and' Charlemagne |journal=Gesta |volume=15 |issue=1/2 |pages=237–239 |year=1976 |last1=Seidel |first1=Linda |s2cid=193434433}}
*{{cite book |last=Southern |first=Pat. |title=The Roman Empire from Severus to Constantine |location=New York |publisher=Routledge |year=2001 |isbn=0-415-23944-3}}
*{{cite journal |doi=10.2307/3162367 |jstor=3162367 |title=The 'Eusebian Constantine' |journal=Church History |volume=40 |issue=2 |pages=145–155 |year=1971 |last1=Storch |first1=Rudolph H. |s2cid=162937055}}
*{{Cite book |last=Treadgold |first=Warren |title=A History of the Byzantine State and Society |publisher=Stanford University Press |year=1997 |isbn=978-0-8047-2630-6 |location=Stanford |author-link=Warren Treadgold |url=https://books.google.com/books?id=nYbnr5XVbzUC}}
*Udoh, Fabian E. "Quand notre monde est devenu chretien", review, ''Theological Studies'', June 2008
*[[Paul Veyne|Veyne, Paul]]. ''L'Empire Gréco-Romain'', Paris: Seuil, 2005. {{ISBN|2-02-057798-4}}
*[[Paul Veyne|Veyne, Paul]].''Quand notre monde est devenu chrétien'', Paris: Albin Michel, 2007. {{ISBN|978-2-226-17609-7}}
*{{cite book |last1=Warmington|first1=Brian|editor-last=Drijvers|editor-first=J.W.|chapter=Some Constantinian References in Ammianus|title=The Late Roman World and its Historian: Interpreting Ammianus Marcellinus |year=1999|isbn=0-415-20271-X|chapter-url=https://archive.org/details/lateromanworldit0000unse/page/166/mode/2up|pages=166–167|publisher=Routledge }}
*{{cite journal |doi=10.1017/S1047759400013088 |title=The vision of Constantine |journal=Journal of Roman Archaeology |volume=16 |pages=237–259 |year=2003 |last1=Weiss |first1=Peter |s2cid=162396067}}
*{{cite journal |doi=10.1017/S0009838800043962 |title=Libanius on Constantine |journal=The Classical Quarterly |volume=44 |issue=2 |pages=511–524 |year=1994 |last1=Wiemer |first1=Hans-Ulrich |s2cid=170876695}}
*{{cite book |last1=Wienand |first1=Johannes |title=Der Kaiser als Sieger |year=2012 |isbn=9783050059044|url=https://books.google.com/books?id=RVjyCQAAQBAJ&pg=PA26|doi=10.1524/9783050059044 }}
*Wienand, Johannes (ed.). ''Contested Monarchy. Integrating the Roman Empire in the Fourth Century AD''. Oxford: Oxford University Press 2015.
*{{Cite book |last=Williams |first=Stephen |title=Diocletian and the Roman Recovery |location=New York |publisher=Routledge |year=1997 |isbn=0-415-91827-8 |url=https://books.google.com/books?id=9il6P3TPj-AC}}
*{{cite journal |doi=10.1093/gr/45.1.70 |title=On the Death of the Empress Fausta |journal=Greece and Rome |volume=45 |pages=70–86 |year=1998 |last1=Woods |first1=David |doi-access=free}}
*{{cite journal |doi=10.1093/jts/48.2.531 |title=Where Did Constantine I Die? |journal=The Journal of Theological Studies |volume=48 |issue=2 |pages=531–535 |year=1997 |last1=Woods |first1=D.}}
*{{cite journal |doi=10.2307/1291584 |jstor=1291584 |title=The True Face of Constantine the Great |journal=Dumbarton Oaks Papers |volume=41 |pages=493–507 |year=1987 |last1=Wright |first1=David H.}}
*{{cite book|first = Frances M. |last =
Young |editor1-first = Margaret M. |editor1-last =
Mitchell |editor2-first = Frances M. |editor2-last = Young |title = Origins to Constantine |series = The Cambridge History of Christianity |chapter = Prelude: Jesus Christ, Foundation of Christianity |pages = 1–34 |publisher = Cambridge University Press |location = Cambridge, UK |year = 2006 |isbn=978-1-107-42361-9}}
{{refend}}

== Further reading ==
*Arjava, Antii. ''Women and Law in Late Antiquity''. Oxford: Oxford University Press, 1996. {{ISBN|0-19-815233-7}}
* [[Alessandro Barbero|Barbero, Alessandro]] (2016). ''Costantino il vincitore'' [Constantine the victor]. Rome: Salerno, {{ISBN|978-88-6973-138-9}}.
*{{cite book |last=Baynes |first=Norman H. |title=Constantine the Great and the Christian Church |year=1930 |publisher=Milford |location=London}}
*{{cite book |last=Burckhardt |first=Jacob |title=The Age of Constantine the Great |year=1949 |publisher=Routledge |location=London}}
*{{cite book |last=Cameron |first=Averil |title=The later Roman empire: AD 284–430 |year=1993 |publisher=Fontana Press |location=London |isbn=978-0-00-686172-0}}
*Cowan, Ross (2016). ''[https://www.academia.edu/80315867/Milvian_Bridge_AD_312_Constantines_Battle_for_Empire_and_Faith_proof_ Milvian Bridge AD 312: Constantine's Battle for Empire and Faith]''. Oxford: Osprey Publishing.
* [[Alexander Demandt|Demandt, Alexander]]; Engemann, Josef (eds) (2006). ''Konstantin der Große. Geschichte – Archäologie – Rezeption'' [Constantine the Great. History - Archaeology - Reception]. Trier: Rheinisches Landesmuseum, {{ISBN|3-923319-67-3}}.
* Doležal, Stanislav (2022). ''The Reign of Constantine, 306–337: Continuity and Change in the Late Roman Empire.'' Cham: Palgrave Macmillan.
*{{cite book |editor-last=Eadie |editor-first=John W. |title=The conversion of Constantine |year=1971 |publisher=Holt, Rinehart and Winston |location=New York |isbn=978-0-03-083645-9}}
*Fourlas, Benjamin (2020). "St Constantine and the Army of Heroic Men Raised by Tiberius II Constantine in 574/575. Some Thoughts on the Historical Significance of the Early Byzantine Silver Hoard at Karlsruhe". ''Jahrbuch des Römisch-Germanischen Zentralmuseums'' 62, 2015 [published 2020], 341–375. {{doi|10.11588/jrgzm.2015.1.77142}}
* Girardet, Klaus Martin (2010). ''Der Kaiser und sein Gott. Das Christentum im Denken und in der Religionspolitik Konstantins des Großen'' [The Emperor and his God. Christianity in the Thought and Religious Policy of Constantine the Great]. Berlin/New York: De Gruyter, {{ISBN|978-3-11-022788-8}}.
* Goltz, Andreas; Schlange-Schöningen, Heinrich (eds) (2008). ''Konstantin der Große. Das Bild des Kaisers im Wandel der Zeiten'' [Constantine the Great. The image of the emperor through the ages]. Köln: Böhlau, {{ISBN|978-3-412-20192-0}}.
*Harries, Jill. ''Law and Empire in Late Antiquity''. Cambridge, UK: Cambridge University Press, 2004. Hardcover {{ISBN|0-521-41087-8}} Paperback {{ISBN|0-521-42273-6}}
*Hartley, Elizabeth. ''Constantine the Great: York's Roman Emperor''. York: Lund Humphries, 2004. {{ISBN|978-0-85331-928-3}}.
*Heather, Peter J. "''Foedera'' and ''Foederati'' of the Fourth Century." In ''From Roman Provinces to Medieval Kingdoms'', edited by Thomas F.X. Noble, 292–308. New York: Routledge, 2006. Hardcover {{ISBN|0-415-32741-5}} Paperback {{ISBN|0-415-32742-3}}
*Leithart, Peter J. Defending Constantine: The Twilight of an Empire and the Dawn of Christendom. Downers Grove: IL, InterVarsity Press 2010
*MacMullen, Ramsay. ''Christianizing the Roman Empire A.D. 100–400''. New Haven, CT; London: Yale University Press, 1984. {{ISBN|978-0-300-03642-8}}
*MacMullen, Ramsay. ''Christianity and Paganism in the Fourth to Eighth Centuries''. New Haven: Yale University Press, 1997. {{ISBN|0-300-07148-5}}
*Percival J. [http://cliojournal.wikispaces.com/On+the+Question+of+Constantine%27s+Conversion+to+Christianity On the Question of Constantine's Conversion to Christianity] {{webarchive|url=https://web.archive.org/web/20150614025144/http://cliojournal.wikispaces.com/On%2Bthe%2BQuestion%2Bof%2BConstantine%27s%2BConversion%2Bto%2BChristianity |date=14 June 2015 }}, Clio History Journal, 2008
*{{cite book |last=Pelikán |first=Jaroslav |title=The excellent empire: the fall of Rome and the triumph of the church |year=1987 |publisher=Harper & Row |location=San Francisco |isbn=978-0-06-254636-4 |url=https://archive.org/details/excellentempiref00peli}}
*Velikov, Yuliyan (2013). ''Imperator et Sacerdos''. Veliko Turnovo University Press. {{ISBN|978-954-524-932-7}} (in Bulgarian)

== External links ==
{{Commons|Gaius Flavius Valerius Constantinus|Constantine I}}
{{Wikiquote}}
{{Library resources box |by=no |onlinebooks=yes |others=yes |about=yes |label= Constantine the Great
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*[https://web.archive.org/web/20130219081254/http://www.fourthcentury.com/works-of-constantine/ Complete chronological list of Constantine's extant writings] (archived 19 February 2013)
*{{cite web |url=http://www.third-millennium-library.com/readinghall/GalleryofHistory/CONSTANTINE_THE_GREAT/constantine_DOOR.html |title=Constantine the Great, the Reorganisation of the Empire and the Triumph of the Church |first=John B. |last=Firth |format=BTM |access-date=19 February 2016 |url-status=usurped |archive-url=https://web.archive.org/web/20120315132325/http://www.third-millennium-library.com/readinghall/GalleryofHistory/CONSTANTINE_THE_GREAT/constantine_DOOR.html |archive-date=15 March 2012 }}
*Letters of Constantine: [http://www.seanmultimedia.com/Pie_Constantine_The_Great_Letters_1.html Book 1], [http://www.seanmultimedia.com/Pie_Constantine_The_Great_Letters_2.html Book 2], & [http://www.seanmultimedia.com/Pie_Constantine_The_Great_Letters_3.html Book 3]
*[https://www.britannica.com/eb/article-9109633/Constantine-I Encyclopædia Britannica, Constantine I]
*Henry Stuart Jones (1911). "[[wikisource:1911 Encyclopædia Britannica/Constantine (emperors)|Constantine (emperors)]]". In Chisholm, Hugh (ed.). ''Encyclopædia Britannica''. '''6.''' (11th ed.), Cambridge University Press. pp.&nbsp;988–992.
*Charles George Herbermann and Georg Grupp (1908). "[[wikisource:Catholic Encyclopedia (1913)/Constantine the Great|Constantine the Great]]". In ''Catholic Encyclopedia''. '''4.''' New York: Robert Appleton Company.
*[http://www.bbc.co.uk/northyorkshire/iloveny/romans/2004/constantine_great/ BBC North Yorkshire's site on Constantine the Great]
*[http://www.historyofyork.org.uk/themes/constantine-the-great Constantine's time in York on the 'History of York']
*[http://www.lcms.org/page.aspx?pid=506 Commemorations]
*[https://www.academia.edu/98627208 Roman Legionary AD 284–337: The Age of Diocletian and Constantine the Great]
*[https://www.academia.edu/80315867 Milvian Bridge AD 312: Constantine's Battle for Empire and Faith]

{{s-start}}
{{s-hou | [[Constantinian dynasty]] | 27 February | 272 | 22 May | 337 }}
{{s-reg}}
{{s-bef | before = {{nowrap|[[Constantius Chlorus]]}} }}
{{s-ttl | title = [[List of Roman emperors|Roman emperor]] | years = 306–337 | with= [[Galerius]], [[Severus II]], [[Maxentius]], [[Maximian]],<br /> [[Licinius]], [[Maximinus II]], [[Valerius Valens]] & [[Martinian (emperor)|Martinian]]}}
{{s-aft | after = [[Constantine II (emperor)|Constantine II]]|after2=[[Constantius II]]|after3=[[Constans]] }}
{{s-off}}
{{s-bef | before = [[Constantius Chlorus]]|before2= [[Galerius]] }}
{{s-ttl | title = [[List of Roman consuls|Roman consul]] | years = 307 | regent1 = [[Maximian]]}}
{{s-aft | after = [[Diocletian]]|after2=[[Galerius]]}}
{{s-bef | before = Galerius|before2= Maximinus}}
{{s-ttl | title = Roman consul II–III| years = 312–313 | regent1 = Licinius|regent2=Maximinus}}
{{s-aft | after = [[Gaius Ceionius Rufius Volusianus|C. Ceionius Rufius Volusianus]]|after2= [[Petronius Annianus]] }}
{{s-bef | before = [[Gaius Ceionius Rufius Volusianus|C. Ceionius Rufius Volusianus]]|before2= Petronius Annianus }}
{{s-ttl | title = Roman consul IV| years = 315 | regent1 = Licinius }}
{{s-aft | after = [[Antonius Caecina Sabinus]]|after2=[[Vettius Rufinus]] }}
{{s-bef | before = Licinius|before2= [[Crispus]] }}
{{s-ttl | title = Roman consul V–VI| years = 319–320 | regent1 = [[Licinius II]]|regent2= Constantine II }}
{{s-aft | after = Crispus|after2= Constantine II}}
{{s-bef | before = [[Sextus Anicius Paulinus|Sex. Anicius Paulinus]]|before2=[[Julius Julianus]] }}
{{s-ttl | title = Roman consul VII| years = 326 | regent1 = Constantius II }}
{{s-aft | after = Flavius Constantius|after2= [[Valerius Maximus (praetorian prefect)|Valerius Maximus]] }}
{{s-bef | before = Januarinus|before2=[[Vettius Iustus]] }}
{{s-ttl | title = Roman consul VIII| years = 329 | regent1 = Constantine II }}
{{s-aft | after = [[Gallicanus (consul 330)|Gallicanus]]|after2= [[Aurelius Valerius Symmachus Tullianus]] }}
{{s-reg | leg }}
{{s-bef | before = Constantius Chlorus }}
{{s-ttl | title = [[List of legendary kings of Britain|King of Britain]] }}
{{s-aft | after = [[Eudaf Hen|Octavius]] }}
{{s-end}}

{{History of the Catholic Church}}
{{Roman emperors}}
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{{DEFAULTSORT:Constantine 01}}
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