View source for German nuclear program during World War II

{{Short description|none}}
{{about|German nuclear research during World War II|nuclear power decommissioning in modern Germany|nuclear power phase-out}}
{{Use dmy dates|date=March 2020}}
{{Use American English|date=May 2021}}
{{Infobox military unit
| unit_name                     = German nuclear program
| image                         = {{multiple image|border=infobox|perrow=3/2/2/2|total_width=300
| image1 = Bundesarchiv Bild183-R57262, Werner Heisenberg crop.jpg
| image2 = Bundesarchiv_Bild_183-2005-0331-501%2C_Paul_Harteck.jpg
| image3 = Bothe.jpg
| image4 = UMHK_1917.jpg
| image5 = Rjukan - no-nb digifoto 20160511 00012 NB MIT FNR 04361 (cropped).jpg
| image6 = Leipziger_Uranmaschine.jpg
| image7 = German Experimental Pile - Haigerloch - April 1945.jpg
}} From top to bottom, left to right: {{flatlist|
* [[Werner Heisenberg]], a theoretical physics leader of the project
* [[Paul Harteck]], an experimental leader
* [[Walter Bothe]], a leader on the project's [[cyclotron]]s
* Uranium processing in [[Katanga Province|Katanga]], [[Belgian Congo]]
* [[Vemork]], the project's source of [[heavy water]]
* [[Leipzig L-IV]], an early nuclear experiment
* [[Alsos Mission]] soldiers dismantle the [[Haigerloch research reactor|Haigerloch atomic pile]]
}}
| image_size                    = 250px
| start_date                    = April 1939
| country                       = {{flagcountry|Nazi Germany}}
| patron                        = {{ubl|[[Wehrmacht|Army Ordnance Office]]|[[Reich Research Council]]}}
| size                          = 
| nickname                      = {{ubl|Uranverein|Uranprojekt}}
| colors                        = 
| colors_label                  = 
| march                         = 
| mascot                        = 
| equipment                     = 
| equipment_label               = 
| anniversaries                 = 
| decorations                   = 
| battle_honours                = 
| battle_honours_label          = 
| disbanded                     = 1945{{Efn|Due to the surrender of Germany. The program effort ceased due to the [[Battle of Berlin|Fall of Berlin]].}}
| flying_hours                  = 
| website                       = 
}}

[[Nazi Germany]] undertook several research programs relating to [[nuclear technology]], including [[nuclear weapons]] and [[nuclear reactors]], before and during [[World War II]]. These were variously called {{lang|de|'''Uranverein'''}} ({{transliteration|en|Uranium Society}}) or {{lang|de|'''Uranprojekt'''}} ({{transliteration|en|Uranium Project}}). The first effort started in April 1939, just months after the [[discovery of nuclear fission]] in Berlin in December 1938, but ended shortly ahead of the September 1939 [[Invasion of Poland|German invasion of Poland]], for which many German physicists were drafted into the {{lang|de|[[Wehrmacht]]}}. A second effort under the administrative purview of the {{lang|de|Wehrmacht}}'s {{lang|de|[[Waffenamt|Heereswaffenamt]]}} began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: {{lang|de|Uranmaschine}} ([[nuclear reactor]]) development, uranium and [[heavy water]] production, and uranium [[isotope separation]]. Eventually, the German military determined that nuclear fission would not contribute significantly to the war, and in January 1942 the {{lang|de|Heereswaffenamt}} turned the program over to the Reich Research Council ({{lang|de|[[Reichsforschungsrat]]}}) while continuing to fund the activity.

The program was split up among nine major institutes where the directors dominated research and set their own objectives. Subsequently, the number of scientists working on applied nuclear fission began to diminish as many researchers applied their talents to more pressing wartime demands. The most influential people in the {{lang|de|Uranverein}} included [[Kurt Diebner]], [[Abraham Esau]], [[Walther Gerlach]], and [[Erich Schumann]]. Schumann was one of the most powerful and influential physicists in Germany. Diebner, throughout the life of the nuclear weapon project, had more control over nuclear fission research than did [[Walther Bothe]], [[Klaus Clusius]], [[Otto Hahn]], [[Paul Harteck]], or [[Werner Heisenberg]]. Esau was appointed as {{lang|de|[[Reichsmarschall]]}} [[Hermann Göring]]'s [[plenipotentiary]] for [[nuclear physics]] research in December 1942, and was succeeded by Walther Gerlach after he resigned in December 1943.

Politicization of German [[academia]] under the [[Nazism|Nazi]] regime of 1933–1945 had driven many physicists, engineers, and mathematicians out of Germany as early as 1933. Those of [[Jewish]] heritage who did not leave were quickly purged, further thinning the ranks of researchers. The politicization of the universities, along with  [[Wehrmacht|German armed forces]] demands for more manpower (many scientists and technical personnel were conscripted, despite possessing technical and engineering skills), substantially reduced the number of able German physicists.<ref>{{Cite book |last=Judt |first=Matthias |author2=Burghard Ciesla |title=Technology transfer out of Germany after 1945 |publisher=Routledge |year=1996 |page=55 |isbn=978-3-7186-5822-0}}</ref>

Developments took place in several phases, but in the words of historian Mark Walker, it ultimately became "frozen at the laboratory level" with the "modest goal" to "build a nuclear reactor which could sustain a [[nuclear fission]] chain reaction for a significant amount of time and to achieve the complete separation of at least tiny amounts of the uranium isotopes". The scholarly consensus is that it failed to achieve these goals, and that despite fears at the time, the Germans had never been close to producing nuclear weapons.{{sfn|Walker|1995|pp=198-9}}<ref>{{Cite journal|last1=Grasso |first1=Giacomo |last2=Oppici|first2=Carlo|last3=Rocchi|first3=Federico|last4=Sumini|first4=Marco|date=2009 |title=A Neutronics Study of the 1945 Haigerloch B-VIII Nuclear Reactor|url=http://link.springer.com/10.1007/s00016-008-0396-0 |journal=Physics in Perspective|language=en|volume=11|issue=3 |pages=318–335|doi=10.1007/s00016-008-0396-0|bibcode=2009PhP....11..318G|s2cid=122294499|issn=1422-6944|url-access=subscription}}</ref> With the war in Europe ending in early 1945, various [[Allies of World War II|Allied powers]] competed with each other to obtain surviving components of the German nuclear industry (personnel, facilities, and [[materiel]]), as they did with the pioneering [[V-2 rocket|V-2]] [[SRBM]] program.

==Discovery of nuclear fission==
{{Main|Discovery of nuclear fission}}

In December 1938, German chemist [[Otto Hahn]] and his assistant [[Fritz Strassmann]] sent a manuscript to the German science journal ''[[Die Naturwissenschaften|Naturwissenschaften]]'' ("Natural Sciences") reporting that they had detected and identified the element [[barium]] after bombarding [[uranium]] with [[neutrons]].<ref>O. Hahn and F. Strassmann ''Über den Nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle'' (''On the detection and characteristics of the alkaline earth metals formed by irradiation of uranium with neutrons''), ''Naturwissenschaften'' Volume 27, Number 1, 11–15 (1939). The authors were identified as associated with the ''Kaiser-Wilhelm-Institut für Chemie'', Berlin-Dahlem. Received 22 December 1938.</ref> Their article was published on 6 January 1939. On 19 December 1938, eighteen days before the publication, Otto Hahn communicated these results and his conclusion of a ''bursting'' of the uranium nucleus in a letter to his colleague and friend [[Lise Meitner]], who had fled Germany in July to the Netherlands and then to Sweden.<ref>Ruth Lewin Sime ''Lise Meitner's Escape from Germany'', ''American Journal of Physics'' Volume 58, Number 3, 263–267 (1990).</ref> Meitner and her nephew [[Otto Robert Frisch]] confirmed Hahn's conclusion of a ''bursting'' and correctly interpreted the results as "[[nuclear fission]]" – a term coined by Frisch.<ref>Lise Meitner and O. R. Frisch ''Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction'', ''Nature'', Volume 143, Number 3615, 239–240 [http://www.nature.com/physics/looking-back/meitner/index.html (11 February 1939)]. The paper is dated 16 January 1939. Meitner is identified as being at the Physical Institute, Academy of Sciences, Stockholm. Frisch is identified as being at the Institute of Theoretical Physics, University of Copenhagen.</ref> Frisch confirmed this experimentally on 13 January 1939.<ref>
O. R. Frisch ''Physical Evidence for the Division of Heavy Nuclei under Neutron Bombardment'', ''Nature'', Volume 143, Number 3616, 276–276 [http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Frisch-Fission-1939.html (18 February 1939)] {{webarchive |url=https://web.archive.org/web/20090123165907/http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Frisch-Fission-1939.html |date=23 January 2009 }}. The paper is dated 17 January 1939. [The experiment for this letter to the editor was conducted on 13 January 1939; see Richard Rhodes, ''The Making of the Atomic Bomb'' 263 and 268 (Simon and Schuster, 1986).]
</ref><ref>In 1944 Hahn received the [[Nobel Prize for Chemistry]] for the discovery and the radiochemical proof of nuclear fission. Some American historians have documented their view of the history of the discovery of nuclear fission and believe Meitner should have been awarded the Nobel Prize with Hahn. See {{harvnb|Sime|2005|}}, {{harvnb|Sime|1997|}} and {{harvnb|Crawford|Sime|Walker|1997|}}</ref>

==First ''Uranverein'' and other early 1939 efforts==
On 22 April 1939, after hearing a colloquium paper by his colleague [[Wilhelm Hanle]] at the [[University of Göttingen]] proposing the use of [[uranium]] [[nuclear fission|fission]] in an ''Uranmaschine'' (uranium machine, i.e., [[nuclear reactor]]), [[Georg Joos]], along with Hanle, notified Wilhelm Dames, at the ''[[Reichserziehungsministerium]]'' (REM, Reich Ministry of Education), of potential military and economic applications of nuclear energy. [[Abraham Esau]], a physicist at the Reich Research Council of the REM, organized a meeting for what become informally known as a ''Uranverein'' (Uranium Club). The group included the physicists [[Walther Bothe]], [[Robert Döpel]], [[Hans Geiger]], [[Wolfgang Gentner]] (probably sent by [[Walther Bothe]]), [[Wilhelm Hanle]], [[Gerhard Hoffmann (physicist)|Gerhard Hoffmann]], and [[Georg Joos]]; [[Peter Debye]] was invited, but he did not attend. After this, informal work began at the [[University of Göttingen|Georg-August University of Göttingen]] by Joos, Hanle, and their colleague [[Reinhold Mannkopff]]. Formally the group of physicists was known as the ''Arbeitsgemeinschaft für Kernphysik'' (Nuclear Physics Association). This initial work at Göttingen lasted until the fall of 1939, when Joos and Hanle were drafted into other military research.{{sfn|Kant|2002|loc=Reference 8 on p. 3}}{{sfn|Hentschel|Hentschel|1996|loc=p. 363-4 and Appendix F; see the entries for Esau, Harteck and Joos. See also the entry for the KWIP in Appendix A and the entry for the HWA in Appendix B}}<ref name=Macrakis1993>{{harvnb|Macrakis|1993|pp=164–69}}.</ref><ref name=Mehra_Rechenberg_01>{{harvnb|Mehra|Rechenberg|2001|loc=Volume 6, Part 2, pp. 1010–1}}.</ref>

Independently of this effort, [[Paul Harteck]], director of the physical chemistry department at the [[University of Hamburg]] and an advisor to the ''[[Heereswaffenamt]]'' (HWA, Army Ordnance Office), and his teaching assistant [[Wilhelm Groth]] wrote a letter on 24 April 1939 to Army Ordnance which also mentioned the military application of nuclear chain reactions. Harteck would not receive a reply until August 1939, however, as part of the second ''Uranverein''.{{sfn|Walker|1993|pp=17-18}}

Also independently of the first ''Uranverein'', [[Nikolaus Riehl]], the head of the scientific headquarters at ''[[Auergesellschaft]]'' (usually known as just "Auer"), a German industrial firm, read a June 1939 paper by [[Siegfried Flügge]], on the technical use of nuclear energy from uranium.<ref>Siegfried Flügge ''Kann der Energieinhalt der Atomkerne technisch nutzbar gemacht werden?'', [[Die Naturwissenschaften]] Volume 27, Issues 23/24, 402–10 (9 June 1939).</ref><ref>Also see: Siegfried Flügge ''Die Ausnutzung der Atomenergie. Vom Laboratoriumsversuch zur Uranmaschine&nbsp;– Forschungsergebnisse in Dahlem'', ''Deutsche Allgemeine Zeitung'' No. 387, Supplement (15 August 1939). English translation: Document No.&nbsp;74 ''Siegfried Flügge: Exploiting Atomic Energy. From the Laboratory Experiment to the Uranium Machine&nbsp;– Research Results in Dahlem [15 August 1939]'' in {{harvnb|Hentschel|Hentschel|1996|pp=197–206}}. [This article is Flügge's popularized version of the June 1939 article in ''Die Naturwissenschaften''.]</ref> As Auer had a substantial amount of [[uranium]] on hand as a waste product from the process of extracting [[radium]], Riehl recognized the possibility of uranium production as a business opportunity for the company, and July 1939 contacted the Army Ordnance Office on the matter.{{sfn|Walker|1993|pp=17-18}} Army Ordnance eventually provided an order for the production of uranium oxide, which took place in the Auer plant in [[Oranienburg]], north of Berlin.{{sfn|Hentschel|Hentschel|1996|loc=p. 369, Appendix F, see the entry for Riehl, and Appendix D, see the entry for Auergesellschaft}}{{sfn|Riehl|Seitz|1996|p=13}}

These three efforts, as noted, were independent and lasted until the fall of 1939, when the outbreak of World War II disrupted the work at Göttingen, and also prompted the HWA (Army Ordnance) to take over the work from the Reich Research Council. After the fact, this early work was designated as the first ''Uranverein'', with the HWA's reorganized project being designated the second ''Uranverein''.

==Second ''Uranverein''==
[[File:Atomreaktor Museum Stadtilm.jpg|thumb|''Atomkeller'' in [[Stadtilm]]]]

In August 1939, just before the German invasion of Poland precipitated the formal start of World War II, the Army Ordnance Office (HWA) moved to take over the work of the ''Reichsforschungsrat'' (RFR, Reich Research Council) of the Reich Education Ministry (REM), and ordered the RFR to halt all experiments and work on nuclear energy. Esau protested that the discovery of nuclear fission was too recent to warrant such an action, but was ignored.{{sfn|Walker|1993|pp=18}} These actions were initiated by the physicist [[Kurt Diebner]], an advisor to the HWA, in association with [[Erich Bagge]]. In September 1939, Diebner organized a meeting in Berlin on 16 September.{{sfn|Hentschel|Hentschel|1996|loc=p. 365, fn. 18.}}{{sfn|Bernstein|2001|pp=xxii-xxiii}}

The invitees to this meeting included [[Walther Bothe]], [[Siegfried Flügge]], [[Hans Geiger]], [[Otto Hahn]], [[Paul Harteck]], [[Gerhard Hoffmann (physicist)|Gerhard Hoffmann]], [[Josef Mattauch]], and [[Georg Stetter]]. Its purpose, as Bagge later recalled, was

{{blockquote|to make all preparations to be able to answer beyond doubt the question of whether generating nuclear energy was feasible. It would certainly be very nice if it were possible to acquire a new source of energy, it would also very probably have military importance; a negative answer would be just as important, since we could be sure that the enemy would also not be able to make use of it.{{sfn|Hentschel|Hentschel|1996|loc=p. 365, fn. 18.}}}}

This group, like the one before it, referred to itself informally as a ''Uranverein''. A second meeting was held soon thereafter, and included [[Klaus Clusius]], [[Robert Döpel]], [[Werner Heisenberg]], and [[Carl Friedrich von Weizsäcker]]. Also at this time, the ''Kaiser-Wilhelm Institut für Physik'' (KWIP, Kaiser Wilhelm Institute for Physics, after World War II the [[Max Planck Institute for Physics]]), in [[Dahlem (Berlin)|Berlin-Dahlem]], was placed under HWA authority, with Diebner as the administrative director, and the military control of the nuclear research commenced.<ref name=Macrakis1993/><ref name=Mehra_Rechenberg_01/>{{sfn|Hentschel|Hentschel|1996|loc=pp. 363–4 and Appendix F; see the entries for Diebner and Döpel. See also the entry for the KWIP in Appendix A and the entry for the HWA in Appendix B}} Although the official slogan of the government was "We must make use of physics for warfare", Heisenberg and his colleagues decided that they should instead "make use of warfare for physics".<ref>{{cite web|title=Interview with Werner Heisenberg by Joseph J. Ermenc (August 29, 1967)|url=https://www.haigerloch.de/de/Freizeit-Tourismus/Kunst,Kultur-und-Kernspaltung/Atomkeller/Interview-mit-Werner-Heisenberg|publisher=Stadt Haigerloch}}: "But this [a race for the atomic bomb] was not the situation. The situation psychologically was different. It was a new situation for us scientists in Germany. Now for the first time we could get money from our government to do something interesting and we intended to use this situation. The official slogan of the government was: We must make use of physics for warfare. We turned it around for our slogan: We must make use of warfare for physics. It was a very natural reaction. Everybody likes to make interesting experiments."</ref>

Heisenberg said that in 1939, the physicists at this second meeting concluded that "in principle atomic bombs could be made, but they also emphasized that it would take a number of years",{{sfn| Ermenc|1989|p=34}} certainly not less than five. He also said that he "didn't report it to the [[Führer]] until two weeks later and very casually because I did not want the Führer to get so interested that he would order great efforts immediately to make the atomic bomb. [[Albert Speer|Speer]] felt it was better that the whole thing should be dropped and the Führer also reacted that way."{{sfn| Ermenc|1989|p=34}} He said they presented the matter in this way for their own personal safety, as the probability of success was nearly zero, and that if many thousands of people working on an expensive and time-consuming project ended up developing nothing, there could be "extremely disagreeable consequences"{{sfn| Ermenc|1989|p=34}} for them. ''[[Luftwaffe]]'' ''[[Generalfeldmarschall]]'' [[Erhard Milch]] asked how long America might take to develop a nuclear weapon, and was given an estimate of 1944, though the group, among themselves, "believed that they would not be able to make atomic bombs before three or four years."{{sfn| Ermenc|1989|p=27}}

When it was apparent that the nuclear weapon project would not make a decisive contribution to ending the war in the near term, control of the KWIP was returned in January 1942 to its umbrella organization, the ''[[Kaiser-Wilhelm Gesellschaft]]'' (the Kaiser Wilhelm Society, after World War II the [[Max Planck Society|Max-Planck-Gesellschaft]]). HWA control of the project was subsequently passed to the RFR in July 1942. The nuclear weapon project thereafter maintained its ''kriegswichtig'' (war importance) designation, and funding continued from the military, but it was then split into the areas of [[uranium]] and [[heavy water]] production, uranium isotope separation, and the ''Uranmaschine'' (uranium machine, i.e., nuclear reactor). It was in effect broken up between institutes where the different directors dominated the research and set their own research agendas.<ref name=Macrakis1993/>{{sfn|Hentschel|Hentschel|1996|loc=See the entry for the KWIP in Appendix A and the entries for the HWA and the RFR in Appendix B. Also see p. 372 and footnote 50 on p. 372}}{{sfn|Walker|1993|pp=49–53}} The dominant personnel, facilities, and areas of research were:{{sfn|Walker|1993|pp=52–3}}{{sfn|Kant|2002|p=19}}<ref>[http://www.deutsches-museum.de/archiv/archiv-online/geheimdokumente/forschungszentren Deutsches Museum] "Geheimdokumente zu den Forschungszentren": Gottow, Hamburg, Berlin, Leipzig und Wien, Heidelberg, Straßburg</ref>
* [[Walther Bothe]]{{snd}}Director of the ''Institut für Physik'' (Institute for Physics) at the ''Kaiser-Wilhelm Institut für medizinische Forschung'' (KWImF, Kaiser Wilhelm Institute for Medical Research, after 1948 the [[Max Planck Institute for Medical Research|Max-Planck-Institut für medizinische Forschung]]), in [[Heidelberg]].
** Measurement of nuclear constants. ''6 physicists''
* [[Klaus Clusius]]{{snd}}Director of the Institute for Physical Chemistry at the [[Ludwig Maximilian University of Munich]]
** [[Isotope separation]] and [[heavy water]] production. ''ca. 4 physical chemists and physicists''
* [[Kurt Diebner]]{{snd}}Director of the HWA ''Versuchsstelle'' (testing station) in Gottow and of the RFR experimental station in [[Stadtilm]], Thuringia; he was also an advisor to the HWA on nuclear physics.
** Measurement of nuclear constants. ''ca. 6 physicists''
* [[Otto Hahn]]{{snd}}Director of the ''Kaiser-Wilhelm-Institut für Chemie'' (KWIC, Kaiser Wilhelm Institute for Chemistry, after World War II the ''[[Max Planck Institute for Chemistry|Max Planck Institut für Chemie{{snd}}Otto Hahn Institut]]''), in [[Dahlem (Berlin)|Berlin-Dahlem]].
** [[Transuranium element|Transuranic elements]], fission products, isotope separation, and measurement of nuclear constants. ''ca. 6 chemists and physicists''
* [[Paul Harteck]]{{snd}}Director of the Physical Chemistry Department of the [[University of Hamburg]].
** Heavy water production and isotope production. ''5 physical chemists, physicists, and chemists''
* [[Werner Heisenberg]]{{snd}}Director of the Department of Theoretical Physics at the [[University of Leipzig]] until summer 1942; thereafter acting director of the ''Kaiser-Wilhelm-Institut für Physik'' (Kaiser Wilhelm Institute for Physics), in [[Dahlem (Berlin)|Berlin-Dahlem]].
** ''Uranmaschine'', isotope separation, and measurement of nuclear constants. ''ca. 7 physicists and physical chemists''
* [[Hans Kopfermann]]{{snd}}Director of the Second Experimental Physics Institute at the [[University of Göttingen|Georg-August University of Göttingen]].
** Isotope separation. ''2 physicists''
* [[Nikolaus Riehl]]{{snd}}Scientific Director of the [[Auergesellschaft]].
** Uranium production. ''ca. 3 physicists and physical chemists''
* [[Georg Stetter]]{{snd}}Director of the ''II. Physikalisches Institut'' (Second Physics Institute) at the [[University of Vienna]].
** Transuranic elements and measurement of nuclear constants. ''ca. 6 physicists and physical chemists''

The point in 1942 when the army relinquished control of the project was its zenith in terms of the number of personnel devoted to the effort, and this was no more than about seventy scientists, with about forty devoting more than half their time to nuclear fission research. After this the number diminished dramatically, and many of those not working with the main institutes stopped working on nuclear fission and devoted their efforts to more pressing war related work.{{sfn|Walker|1993|loc=p. 52 and Reference n. 40 on p. 262}}

On 4 June 1942, a conference regarding the project, initiated by [[Albert Speer]] as head of the "[[Reich Ministry for Armament and Ammunition]]" (RMBM: '' Reichsministerium für Bewaffnung und Munition''; after late 1943 the Reich Ministry for Armament and War Production), decided on its continuation merely for the aim of energy production.{{sfn|Hanle|Rechenberg|1982|}} On 9 June 1942, [[Adolf Hitler]] issued a decree for the reorganization of the RFR as a separate legal entity under the RMBM; the decree appointed Reich Marshal [[Hermann Göring]] as its president.<ref>Document 98: ''The Führer's Decree on the Reich Research Council'', 9 June 1942, in {{harvnb|Hentschel|Hentschel|1996|p=303}}.</ref> The reorganization was done under the initiative of Minister [[Albert Speer]] of the RMBM; it was necessary as the RFR under [[Bernhard Rust]] the Minister of Science, Education and National Culture was ineffective and was not achieving its purpose.<ref>Read [[Samuel Abraham Goudsmit|Samuel Goudsmit's]] account and interpretation of the role of the RFR in Document 111: ''War Physics in Germany'', January 1946, in {{harvnb|Hentschel|Hentschel|1996|pp=345–52}}.</ref> The hope was that Göring would manage the RFR with the same discipline and efficiency as he had the aviation sector. A meeting was held on 6 July 1942 to discuss the function of the RFR and set its agenda. The meeting was a turning point in Nazi attitudes towards science, as well as recognition that the policies which drove Jewish scientists out of Germany were a mistake, as the Reich needed their expertise. [[Abraham Esau]] was appointed on 8 December 1942 as [[Hermann Göring|Hermann Göring's]] ''Bevollmächtigter'' (plenipotentiary) for nuclear physics research under the RFR; in December 1943, Esau was replaced by [[Walther Gerlach]]. In the final analysis, placing the RFR under Göring's administrative control had little effect on the German nuclear weapon project.<ref name=Council42>Document 99: ''Record of Conference Regarding the Reich Research Council'', 6 July 1942, in {{harvnb|Hentschel|Hentschel|1996|loc=pp. 304–8}}.</ref>{{sfn|Macrakis|1993|pp=91–4}}{{sfn|Hentschel|Hentschel|1996|loc=Appendix F; see the entries for Esau and Gerlach}}{{sfn|Walker|1993|p=86}}

Speer states that the project to develop the atom bomb was scuttled in the autumn of 1942. Though the scientific solution was there, it would have taken all of Germany's production resources to produce a bomb, and then no sooner than 1947.<ref name=Speer1995>{{cite book |last1=Speer |first1=Albert |title=Inside the Third Reich |date=1995 |location=London |publisher=Weidenfeld & Nicolson |isbn=9781842127353 |pages=314–20 }}</ref> Development did continue with a "uranium motor" for the navy and development of a German [[cyclotron]]. However, by the summer of 1943, Speer released the remaining 1200 [[metric ton]]s of uranium stock for the production of solid-core ammunition.<ref name=Speer1995/>

Over time, the HWA and then the RFR controlled the German nuclear weapon project. The most influential people were [[Kurt Diebner]], [[Abraham Esau]], [[Walther Gerlach]], and [[Erich Schumann]]. Schumann was one of the most powerful and influential physicists in Germany. He was director of the Physics Department II at the Frederick William University (later, University of Berlin), which was commissioned and funded by the ''Oberkommando des Heeres'' (OKH, Army High Command) to conduct physics research projects. He was also head of the research department of the HWA, assistant secretary of the Science Department of the OKW, and ''Bevollmächtigter'' (plenipotentiary) for high explosives. Diebner, throughout the life of the nuclear weapon project, had more control over nuclear fission research than did [[Walther Bothe]], [[Klaus Clusius]], Otto Hahn, [[Paul Harteck]], or Werner Heisenberg.{{sfn|Walker|1993|p=208}}{{sfn|Hentschel|Hentschel|1996|loc=Appendix F; see the entry for Schumann. Also see footnote 1 on p. 207}}

==Isotope separation==
[[Paul Peter Ewald]], a member of the ''Uranverein'', had proposed an [[Isotope separation#Electromagnetic|electromagnetic isotope separator]], which was thought applicable to <sup>235</sup>U production and enrichment. This was picked up by [[Manfred von Ardenne]], who ran a private research establishment.

In 1928, von Ardenne had come into his inheritance with full control as to how it could be spent, and he established his private research laboratory the ''Forschungslaboratorium für Elektronenphysik'',<ref>{{cite news |date=20 January 2006 |title=Zur Ehrung von Manfred von Ardenne |publisher=sachsen.de |url=http://www.sachsen.de/sadra/887.htm |archive-url=https://web.archive.org/web/20080325042138/http://www.sachsen.de/sadra/887.htm |archive-date=25 March 2008}}</ref> in Berlin-Lichterfelde, to conduct his own research on radio and television technology and [[electron microscopy]]. He financed the laboratory with income he received from his inventions and from contracts with other concerns. For example, his research on nuclear physics and high-frequency technology was financed by the ''[[Reichspostministerium]]'' (RPM, Reich Postal Ministry), headed by [[Wilhelm Ohnesorge]]. Von Ardenne attracted top-notch personnel to work in his facility, such as the nuclear physicist [[Fritz Houtermans]], in 1940. Von Ardenne had also conducted research on isotope separation.<ref>{{cite web |title=Manfred Baron von Ardenne 1907–1997 |website= Lemo – Lebendiges Museum Online |url=http://www.dhm.de/lemo/html/biografien/ArdenneManfred/ }}</ref>{{sfn|Hentschel|Hentschel|1996|loc=Appendix F; see entry for Ardenne. Also see the entry for the ''Reichspostministerium'' in Appendix C}} Taking Ewald's suggestion he began building a prototype for the RPM. The work was hampered by war shortages and ultimately ended by the war.<ref>{{harvnb|Walker|1993|loc=pp. 83–84, 170, 183, and Reference n. 85 on p. 247}}. See also {{cite book |last=Ardenne von |first=Manfred |author-link=Manfred von Ardenne |year=1997 |title=Erinnerungen, fortgeschrieben. Ein Forscherleben im Jahrhudert des Wandels der Wissenschaften und politischen Systeme |publisher=Droste |isbn=978-3770010882}}</ref>

Aside from the ''Uranverein'' and von Ardenne's team in Berlin-Lichterfelde, there was also a small research team in the [[Henschel & Son|Henschel Flugzeugwerke]]: the study group under the direction of Prof. Dr. Ing. Herbert Wagner (1900–1982) searched for alternative sources of energy for airplanes and became interested in nuclear energy in 1940. In August 1941, they finished a detailed internal survey of the history and potential of technical nuclear physics and its applications (''Übersicht und Darstellung der historischen Entwicklung der modernen technischen Kernphysik und deren Anwendungsmöglichkeit sowie Zusammenfassung eigener Arbeitsziele und Pläne'', signed by Herbert Wagner and Hugo Watzlawek (1912–1995) in Berlin. Their application to the Aviation Ministry (RLM) to found and fund an Institute for Nuclear Technology and Nuclear Chemistry (''Reichsinstituts für Kerntechnik und Kernchemie'') failed, but Watzlawek continued to explore potential applications of nuclear energy and wrote a detailed textbook on technical nuclear physics. It includes one of the most detailed presentations of contemporary German knowledge about the various processes of isotope separation, and recommends their combined usage to get to sufficient amounts of enriched uranium. Walther Gerlach refused to print this textbook, but it is preserved as a typed manuscript and it appeared after the War in 1948 virtually unchanged (with just a few additions on the US atomic bomb released in 1945).<ref>See {{cite book |last=Watzlawek |first=Hugo |year=1948 |title=Lehrbuch der technischen Kernphysik |publisher=Deuticke}}; the original typescript is available in the online-Archive of the Deutsches Museum München at https://digital.deutsches-museum.de/item/FA-002-752/</ref> In October 1944, Hugo Watzlawek wrote an article on the potential usage of nuclear energy and its many potential applications. In his view, to follow up this route of research and development was the "new pathway" to becoming the "Master of the World".<ref>See {{cite journal |last=Hentschel |first=Klaus |date=2020 |title=''Der neue Weg'': Mit inneratomarer Energie zum ''Herrn der Welt'' werden – Zu einem bislang unbekannten Typoskript vom Oktober 1944 (Inneratomic Energy as the ''New Path'' Towards Becoming ''Master of the World – On a Hitherto Unknown Typescript from October 1944'' |journal=NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin |volume=28 |issue=2 |pages=121–147 |doi=10.1007/s00048-020-00241-z |pmid=32415322 |doi-access=free }}</ref>

==Moderator production==

[[File:Rjukan - no-nb digifoto 20160511 00012 NB MIT FNR 04361 (cropped).jpg|thumb|The [[Vemork]] plant at Norsk Hydro, Norway, after the war. The heavy water was produced in the front building, the Hydrogen Production Plant.]]

The production of [[heavy water]] was already under way in Norway when the Germans invaded on 9 April 1940. The Norwegian production facilities for heavy water were quickly secured (though some heavy water had already been removed) and improved by the Germans. The Allies and Norwegians had [[Norwegian heavy water sabotage|sabotaged Norwegian heavy water production]] and destroyed stocks of heavy water by 1943. In November 1943, the 800,000 RM were allocated for the development of a German heavy water plant. A pilot plant project was operated by [[IG Farben]] at their [[Leuna Werke]] ammonia plant in [[Merseburg]], run by [[Paul Herold]], but the increasing strain of allied air raids against Germany made such projects increasingly difficult, and no apparent success was achieved.{{sfn|Hentschel|Hentschel|1996|p=321, 375}}

Graphite (carbon) as an alternative was not considered, because the neutron absorption coefficient value for carbon calculated by [[Walther Bothe]] was too high, probably due to the boron in the graphite pieces having high neutron absorption.<ref>{{Cite journal |last=Bethe |first=Hans A. |author-link=Hans Bethe |year=2000 |title=The German Uranium Project |journal=Physics Today |volume=53 |issue=7 |pages=34–6 |doi=10.1063/1.1292473 |bibcode=2000PhT....53g..34B }}</ref>

==Exploitation and denial strategies==
Near the end of World War II, the principal Allied war powers each made plans for exploitation of German science. In light of the implications of nuclear weapons, German nuclear fission and related technologies were singled out for special attention. In addition to exploitation, denial of these technologies, their personnel, and related materials to rival allies was a driving force of their efforts. This typically meant getting to these resources first, which to some extent put the Soviets at a disadvantage in some geographic locations easily reached by the Western Allies, even if the area was allotted to the Soviet zone of occupation at the [[Potsdam Conference]]. At times, all parties were heavy-handed in their pursuit and denial to others.{{sfn|Gimbel|1986|pp=433–51}}{{sfn|Gimbel|1990|}}{{sfn|Goudsmit|1986|}}{{sfn|Naimark|1995|}}{{sfn|Oleynikov|2000|pp=1–30}}

The best known US denial and exploitation effort was [[Operation Paperclip]], a broad dragnet that encompassed a wide range of advanced fields, including jet and rocket propulsion, nuclear physics, and other developments with military applications such as infrared technology. Operations directed specifically towards German nuclear fission were [[Operation Alsos]] and [[Operation Epsilon]], the latter being done in collaboration with the British. In lieu of the codename for the Soviet operation, it is referred to by the historian Oleynikov as the [[Russian Alsos|Russian "Alsos"]].{{sfn|Oleynikov|2000|p=3}}

===American and British===
Berlin had been a location of many German scientific research facilities. To limit casualties and loss of equipment, many of these facilities were dispersed to other locations in the later years of the war.

====Operation Big====
{{Main|Operation Big}}
Unfortunately for the Soviets, the ''Kaiser-Wilhelm-Institut für Physik'' (KWIP, Kaiser Wilhelm Institute for Physics) had mostly been moved in 1943 and 1944 to [[Hechingen]] and its neighboring town of [[Haigerloch]], on the edge of the [[Black Forest]], which eventually became the French occupation zone. This move allowed the Americans to take into custody a large number of German scientists associated with nuclear research. The only section of the institute which remained in Berlin was the low-temperature physics section, headed by {{ill|Ludwig Bewilogua|de|Ludwig Bewilogua}}, who was in charge of the experimental uranium pile.{{sfn|Naimark|1995|pp=208–09}}{{sfn|Bernstein|2001|pp=49–52}}

American Alsos teams carrying out Operation Big raced through [[Baden-Württemberg]] near the war's end in 1945, uncovering, collecting, and selectively destroying ''Uranverein'' elements, including capturing a prototype reactor at Haigerloch and records, heavy water, and uranium ingots at Tailfingen (today part of [[Albstadt]]).<ref>Beck, Alfred M, et al, ''United States Army in World War II: The Technical Services – The Corps of Engineers: The War Against Germany'', 1985 Chapter 24, ''Into the Heart of Germany''</ref> These were all shipped to the US for study and utilization in the US atomic program.<ref>
* {{Cite journal|last1=Koeth|first1=Timothy|last2=Hiebert|first2=Miriam|date=2019|title=Tracking the journey of a uranium cube|journal=Physics Today|language=en|volume=72|issue=5|pages=36–43|doi=10.1063/PT.3.4202|bibcode=2019PhT....72e..36K|s2cid=155333182|issn=0031-9228|doi-access=free}}
* {{cite news |title=Lost Nuclear Material Resurfaces In Maryland |url=https://www.npr.org/2019/08/31/755478866/have-you-seen-any-nazi-uranium-these-researchers-want-to-know |access-date=6 March 2023 |work=NPR}}
</ref> Although many of these materials remain unaccounted for, the [[National Museum of Nuclear Science & History]] displayed a cube of uranium attained from this mission from March 2020.<ref>{{Cite web |title=Dark Cube: Heisenberg's Race for the Bomb |url=https://www.nuclearmuseum.org/see/exhibits/dark-cube-heisenbergs-race-for-the-bomb-opens-march-14 |access-date=2023-08-22 |website=Nuclear Museum |language=en-US}}</ref>

====Operation Epsilon, and Farm Hall====

{{Main|Operation Epsilon}}

[[File:FarmHallLarge.jpg|right|thumb|Farm Hall, Godmanchester]]

A major goal of the [[Operation Alsos]] effort in Germany was the location, capture, and interrogation of German nuclear scientists. This involved some significant effort as many of them had become scattered during the chaotic last weeks of the war in Europe. Ultimately, nine of the prominent German scientists who published reports in ''Kernphysikalische Forschungsberichte'' as members of the ''Uranverein''{{sfn|Walker|1993|loc=pp. 268–74 and Reference n. 40 on p. 262}} were picked up by the Alsos team and incarcerated in England as part of what was called [[Operation Epsilon]]: [[Erich Bagge]], [[Kurt Diebner]], [[Walther Gerlach]], [[Otto Hahn]], [[Paul Harteck]], [[Werner Heisenberg]], [[Horst Korsching]], [[Carl Friedrich von Weizsäcker]], and [[Karl Wirtz]]. Also incarcerated was [[Max von Laue]], although he had nothing to do with the nuclear weapon project. [[Samuel Goudsmit|Goudsmit]], the chief scientific advisor to Operation Alsos, thought von Laue might be beneficial to the post-war rebuilding of Germany and would benefit from the high level contacts he would have in England.{{sfn|Bernstein|2001|pp=50, 363–65}}

The ten scientists were secretly relocated and kept confined and incommunicado with the broader world in [[Farm Hall]], a manor house in [[Godmanchester]]. The legal authority for this, the legal status of the prisoners, and the ultimate intentions of the British were unclear to all involved, to the great discomfort of the scientists. The manor house was wired with [[covert listening device]]s, and conversations between the German scientists were monitored and translated into English. It is unclear whether the scientists were aware, or whether they suspected, that they were being monitored.

Prior to the announcement of Hiroshima, the German scientists, though worried about the future, expressed confidence in their value to the Allies on the basis of their advanced knowledge of nuclear matters. The British then told the scientists that the [[BBC]] had announced the use of the atomic bomb after the attack on Hiroshima. Reactions from the Germans varied; Hahn expressed guilt for his role in the discovery of nuclear fission, while many others, including Heisenberg, expressed incredulity at the report ("I don’t believe a word of the whole thing"). Later that evening, the scientists were allowed to listen to a longer BBC announcement, which invited further debate. Throughout all of this, Heisenberg made arguments that it would take very large amounts of enriched uranium ("about a ton") to make such a weapon. In justifying his reasoning, he gave a brief explanation of how one would calculate the critical mass for an atomic bomb which contained serious errors.{{sfn|Bernstein|2001|pp=115-129}}

The transcripts were declassified in 1992, and this particular section of discussion was subjected to expert scrutiny. Two scientists on the Manhattan Project, [[Edward Teller]] and [[Hans Bethe]], concluded after reading the transcripts that Heisenberg had never done the calculation before. Heisenberg himself, in the transcript, said that, "quite honestly I have never worked it [the critical mass calculation for an atomic bomb] out as I never believed one could get pure [uranium-]235." A week after the bombing, Heisenberg had given a more formal lecture to his colleagues on the physics of the atomic bomb, which corrected many of his early mistakes and indicated a much smaller critical mass. Historians have cited Heisenberg's error as evidence of the degree to which his role in the project had been confined almost entirely to reactors, as the original equation is much more similar to how a reactor would work than to an atomic bomb.{{sfn|Bernstein|2001|pp=129-131, 171, 191-207}}<ref>{{Cite news |last=Popp |first=Manfred |date=2017-01-04 |title=Darum hatte Hitler keine Atombombe |url=https://www.zeit.de/wissen/geschichte/2016-12/ns-zeit-adolf-hitler-atombombe-entwicklung-werner-heisenberg-kernphysik/komplettansicht |website=Die Zeit.}}</ref><ref>{{Citation |last=Teller |first=Edward |title=Heisenberg, Bohr and the atomic bomb |url=https://www.webofstories.com/people/edward.teller/34?o=SH |access-date=2023-08-02 |language=en}}</ref>

At Farm Hall, the German scientists discussed why Germany did not create an atomic bomb, and the United States and United Kingdom did. The transcripts reveal them developing what has been called the ''Lesart'' ("version"). The ''Lesart'' argued that the German scientists ''chose'' not to build a bomb for Hitler, either by dragging their feet, being insufficiently enthusiastic, or, in some versions, active sabotage. The ''Lesart'' both offers up an explanation for their "failure" and also elevates their moral authority above the Allied scientists, despite the fact that they worked for the Nazis. After the war, von Weizsäcker and Heisenberg and several others spread this version of the story to journalists and historians, like [[Robert Jungk]], who reprinted and amplified it uncritically in the 1950s. Already by that time, the historical accuracy of the ''Lesart'' had been challenged forcefully by von Laue (who coined the term ''Lesart'') and nowadays most professional historians of science with knowledge of the subject do not believe that the ''Lesart'' is true.{{sfn|Bernstein|2001|pp=332-335}} As the historian and physicist [[Jeremy Bernstein]] put it in an annotated edition of the Farm Hall transcripts:

{{blockquote|What the Farm Hall reports make transparently clear is that, while they knew a few general principles — the use of fast fission from separated <sup>235</sup>U and the possibility of plutonium&nbsp;—&nbsp;they had not seriously investigated any of the details. All of the really hard problems were left untackled and unsolved. ... They had decided that making a bomb in wartime Germany was unfeasible on technical and economic grounds. It was simply too big and too costly. Morality had nothing to do with it.{{sfn|Bernstein|2001|pp=334}}}}

The ''Lesart'' has been perpetuated in many popular accounts of the German nuclear program, notably in [[Michael Frayn]]'s 1998 play ''[[Copenhagen (play)|Copenhagen]]'', which itself was based heavily on the ''Lesart''-endorsing work of popular history, ''Heisenberg's War'' (1993), by the journalist [[Thomas Powers]].

====Oranienburg plant====
With the interest of the ''Heereswaffenamt'' (HWA, Army Ordnance Office), [[Nikolaus Riehl]], and his colleague [[Günter Wirths]], set up an industrial-scale production of high-purity uranium oxide at the ''[[Auergesellschaft]]'' plant in [[Oranienburg]]. Adding to the capabilities in the final stages of metallic uranium production were the strengths of the Degussa corporation's capabilities in metals production.{{sfn|Hentschel|Hentschel|1996|loc=p. 369 Appendix F (see the entry for Nikolaus Riehl), and Appendix D (see the entry for Auergesellschaft)}}{{sfn|Riehl|Seitz|1996|pp=13, 69}}

The Oranienburg plant provided the uranium sheets and cubes for the ''Uranmaschine'' experiments conducted at the KWIP and the ''Versuchsstelle'' (testing station) of the ''Heereswaffenamt'' (Army Ordnance Office) in Gottow. The G-1 experiment<ref>F. Berkei, W. Borrmann, W. Czulius, [[Kurt Diebner]], Georg Hartwig, [[Karl-Heinz Höcker|K. H. Höcker]], [[Walter Herrmann (physicist)|W. Herrmann]], [[Heinz Pose|H. Pose]], and [[Ernst Rexer]] [https://digital.deutsches-museum.de/de/digital-catalogue/archive-item/FA%20002/629/ ''Bericht über einen Würfelversuch mit Uranoxyd und Paraffin'' G-125] (dated before 26 November 1942). </ref> performed at the HWA testing station, under the direction of [[Kurt Diebner]], had lattices of 6,800 uranium oxide cubes (about 25 tons), in the nuclear moderator paraffin.{{sfn|Riehl|Seitz|1996|p=13}}{{sfn|Hentschel|Hentschel|1996|loc=pp. 369 and 373, Appendix F (see the entry for Nikolaus Riehl and Kurt Diebner), and Appendix D (see the entry for Auergesellschaft)}}

Work of the American Operation Alsos teams, in November 1944, uncovered leads which took them to a company in Paris that handled rare earths and had been taken over by the ''Auergesellschaft''. This, combined with information gathered in the same month through an Alsos team in [[Strasbourg]], confirmed that the Oranienburg plant was involved in the production of uranium and thorium metals. Since the plant was to be in the future Soviet zone of occupation and the Red Army's troops would get there before the Western Allies, General [[Leslie Groves]], commander of the [[Manhattan Project]], recommended to General [[George Marshall]] that the plant be destroyed by aerial bombardment, in order to deny its uranium production equipment to the Soviets. On 15 March 1945, 612 [[B-17 Flying Fortress]] bombers of the [[Eighth Air Force]] dropped 1,506 tons of high-explosive and 178 tons of incendiary bombs on the plant. Riehl visited the site with the Soviets and said that the facility was mostly destroyed. Riehl also recalled long after the war that the Soviets knew precisely why the Americans had bombed the facility—the attack had been directed at them rather than the Germans.{{sfn|Bernstein|2001|pp=50–51}}{{sfn|Naimark|1995|pp=205–07}}{{sfn|Riehl|Seitz|1996|pp=77–79}}{{sfn|Walker|1993|p=156}}<ref>Leslie M. Groves ''Now it Can be Told: The Story of the Manhattan Project'' (De Capo, 1962) pp. 220–22, 230–31.</ref>

===French===
From 1941 to 1947, [[Friedrich Bopp|Fritz Bopp]] was a staff scientist at the KWIP, and worked with the ''Uranverein''. In 1944, he went with most of the KWIP staff when they were evacuated to [[Hechingen]] in Southern Germany due to air raids on Berlin, and became the Institute's Deputy Director. When the [[Operation Alsos|American Alsos]] Mission evacuated Hechingen and [[Haigerloch]], near the end of World War II, French armed forces occupied Hechingen. Bopp did not get along with them and described the initial French policy objectives towards the KWIP as exploitation, forced evacuation to France, and seizure of documents and equipment. The French occupation policy was not qualitatively different from that of the American and Soviet occupation forces, it was just carried out on a smaller scale. In order to put pressure on Bopp to evacuate the KWIP to France, the French Naval Commission imprisoned him for five days and threatened him with further imprisonment if he did not cooperate in the evacuation. During his imprisonment, the [[spectroscopist]] {{ill|Hermann Schüler|de|Hermann Schüler}} , who had a better relationship with the French, persuaded the French to appoint him as Deputy Director of the KWIP. This incident caused tension between the physicists and spectroscopists at the KWIP and within its umbrella organization the ''[[Kaiser Wilhelm Institute|Kaiser-Wilhelm Gesellschaft]]'' (Kaiser Wilhelm Society).{{sfn|Hentschel|Hentschel|1996|loc=Appendix F; see the entry for Bopp}}{{sfn|Walker|1993|pp=186–87}}{{sfn|Bernstein|2001|loc=p. 212 and footnote 5 on p. 212}}<ref>For information on the American and Russian exploitation of Germany after World War II, see: {{harvnb|Naimark|1995}}, {{harvnb|Gimbel|1990|}} and {{harvnb|Gimbel|1986|pp=433–51}}.</ref>

===Soviet===
At the close of World War II, the Soviet Union had special search teams operating in Austria and Germany, especially in Berlin, to identify and obtain equipment, material, intellectual property, and personnel useful to the [[Soviet atomic bomb project]]. The exploitation teams were under the [[Russian Alsos|Soviet Alsos]] and they were headed by [[Lavrentiy Beria]]'s deputy, [[Avraami Zavenyagin|Colonel General A. P. Zavenyagin]]. These teams were composed of scientific staff members, in [[NKVD]] officer's uniforms, from the bomb project's only laboratory, Laboratory No. 2, in Moscow, and included [[Yulii Borisovich Khariton|Yulij Borisovich Khariton]], [[Isaak Kikoin|Isaak Konstantinovich Kikoin]], and [[Lev Artsimovich|Lev Andreevich Artsimovich]]. [[Georgy Flyorov|Georgij Nikolaevich Flerov]] had arrived earlier, although Kikoin did not recall a vanguard group. Targets on the top of their list were the ''Kaiser-Wilhelm Institut für Physik'' (KWIP, [[Kaiser Wilhelm Institute for Physics]]), the Frederick William University (today, the [[Humboldt University of Berlin|University of Berlin]]), and the [[Technische Hochschule]] in Charlottenburg (now [[Technische Universität Berlin]]).{{sfn|Oleynikov|2000|pp=3–8}}{{sfn|Riehl|Seitz|1996|pp=71–83}}{{sfn|Naimark|1995|pp=203–50}}

German physicists who worked on the ''Uranverein'' and were sent to the [[Soviet Union]] to work on the [[Soviet atomic bomb project]] included: {{ill|Werner Czulius|de|Werner Czulius}}, [[Robert Döpel]], [[Walter Herrmann (physicist)|Walter Herrmann]], [[Heinz Pose]], [[Ernst Rexer]], [[Nikolaus Riehl]], and [[Karl Zimmer]]. [[Günter Wirths]], while not a member of the ''Uranverein'', worked for Riehl at the ''[[Auergesellschaft]]'' on reactor-grade uranium production and was also sent to the Soviet Union.

Zimmer's path to work on the Soviet atomic bomb project was through a prisoner of war camp in [[Krasnogorsk, Moscow Oblast|Krasnogorsk]], as was that of his colleagues [[Hans-Joachim Born]] and [[Alexander Catsch]] from the ''Kaiser-Wilhelm Institut für Hirnforschung'' (KWIH, [[Kaiser Wilhelm Institute for Brain Research]], today the ''[[Max-Planck-Institut für Hirnforschung]]''), who worked there for [[Nikolay Timofeev-Ressovsky|N. V. Timofeev-Resovskij]], director of the ''Abteilung für Experimentelle Genetik'' (Department of Experimental Genetics). All four eventually worked for Riehl in the Soviet Union at [[Laboratory B in Sungul']].{{sfn|Riehl|Seitz|1996|pp=121–32}}{{sfn|Oleynikov|2000|pp=11, 15–17}}

[[Manfred von Ardenne|Von Ardenne]], who had worked on isotope separation for the ''[[Reichspostministerium]]'' (Reich Postal Ministry), was also sent to the Soviet Union to work on their atomic bomb project, along with [[Gustav Hertz]], Nobel laureate and director of Research Laboratory II at [[Siemens]], [[Peter Adolf Thiessen]], director of the ''Kaiser-Wilhelm Institut für physikalische Chemie und Elektrochemie'' (KWIPC, Kaiser Wilhelm Institute for Chemistry and Electrochemistry, today the [[Fritz Haber Institute of the MPG|Fritz Haber Institute of the Max-Planck Society]]), and [[Max Volmer]], director of the Physical Chemistry Institute at the [[Technische Hochschule]] in Charlottenburg (now [[Technische Universität Berlin]]), who all had made a pact that whoever first made contact with the Soviets would speak for the rest.<ref>Heinemann-Grüder, Andreas ''Keinerlei Untergang: German Armaments Engineers during the Second World War and in the Service of the Victorious Powers'' in {{harvnb|Renneberg|Walker|2002|p=44}}.</ref> Before the end of World War II, Thiessen, a member of the [[Nazi Party]], had Communist contacts.{{sfn|Hentschel|Hentschel|1996|loc=Appendix F; see the entry for Thiessen}} On 27 April 1945, Thiessen arrived at von Ardenne's institute in an armored vehicle with a major of the Soviet Army, who was also a leading Soviet chemist, and they issued Ardenne a protective letter (''Schutzbrief'').{{sfn|Oleynikov|2000|pp=5, 11–13}}

==Comparison to the Manhattan Project==
{{Main|Manhattan Project}}
The United States, British, and Canadian governments worked together to create the Manhattan Project that developed the uranium and plutonium atomic bombs.  Its success has been attributed to meeting all four of the following conditions:{{sfn|Landsman|2002|pp=318–19}}

# A strong initial drive, by a small group of scientists, to launch the project.
# Unconditional government support from a certain point in time.
# Essentially unlimited manpower and industrial resources.
# A concentration of brilliant scientists devoted to the project.

Even with all four of these conditions in place, the Manhattan Project succeeded only after the war in Europe had been brought to a conclusion.

In comparison to the Manhattan Project, mutual distrust existed between the German government and some scientists.<ref>Wilhelm Hanle, ''Memoiren''. I. Physikalisches Institut, Justus-Liebig-Universität, 1989.</ref><ref>{{cite book |last=Arnold |first=Heinrich |date=2011 |title=Robert Döpel and his Model of Global Warming |publisher=ilmedia |page=27 |url=http://www.db-thueringen.de/servlets/DocumentServlet?id=17744 }}</ref> By the end of 1941, it was already apparent among German science and military elites that the German nuclear weapon project would not make a decisive contribution to ending the German war effort in the near term, and control of the project was relinquished by the ''Heereswaffenamt'' (HWA, Army Ordnance Office) to the ''Reichsforschungsrat'' (RFR, Reich Research Council) in July 1942. 

As to condition four, the high priority allocated to the Manhattan Project allowed for the recruitment and concentration of capable scientists on the project. In Germany, on the other hand, a great many young scientists and technicians who would have been of great use to such a project were conscripted into the German armed forces, while others had fled the country before the war due to antisemitism and political persecution.<ref name=Mangravite>{{cite journal|last1=Mangravite|first1=Andrew|title=Magical Thinking|journal=Distillations|date=2015|volume=1|issue=4|pages=44–45|url=https://www.sciencehistory.org/distillations/magazine/magical-thinking|access-date=22 March 2018}}</ref><ref name=Ball>{{cite book|last1=Ball|first1=Philip|author-link=Philip Ball |title=Serving the Reich : the struggle for the soul of physics under Hitler|date=2014|publisher=University of Chicago Press|location=Chicago|isbn=978-0226204574}}</ref><ref>{{Cite book |last=Van der Vat |first=Dan |date=1997 |title=The Good Nazi: The Life and Lies of Albert Speer |publisher=Houghton Mifflin Harcourt |isbn=978-039565243-5 }} [https://archive.org/details/goodnazilifelies00vand/page/138 p. 138]</ref>

Whereas [[Enrico Fermi]], a scientific Manhattan Project leader, had a "unique double aptitude for theoretical and experimental work" in the 20th century,{{sfn|Hanle|Rechenberg|1982|}} the successes at Leipzig until 1942 resulted from the cooperation between the theoretical physicist Werner Heisenberg and the experimentalist [[Robert Döpel]]. Most important was their experimental proof of an effective neutron increase in April 1942.<ref>Robert and [[Klara Döpel]], Werner Heisenberg, ''Der experimentelle Nachweis der effektiven Neutronenvermehrung in einem Kugel-Schichten-System aus D2O und Uran-Metall''. Facsimile: [http://www.deutsches-museum.de/archiv/archiv-online/Geheimdokumente Forschungszentren/Leipzig/Neutronenvermehrung (1942)]. Published 1946 in: Heisenberg, W., Collected Works Vol. A II (Eds. W. Blum, H.-P Dürr and [[Helmut Rechenberg|H. Rechenberg]], Berlin etc. (1989), pp. 536–44.</ref> At the end of July of the same year, the group around Fermi also succeeded in the neutron increase within a reactor-like arrangement.

In June 1942, some six months before the American [[Chicago Pile-1]] achieved man-made [[Criticality (status)|criticality]] for the first time anywhere, Döpel's L-IV "''Uran-Maschine''" [[Leipzig L-IV experiment accident|was destroyed]] by a chemical explosion introduced by [[oxygen]],<ref>This was the first accident that disrupted a nuclear energy assembly; cf. Reinhard Steffler, ''Reaktorunfälle und die Handlungen der Feuerwehr: Leipzig, Tschernobyl und Fukushima&nbsp;– eine erste Analyse.'' Elbe-Dnjepr-Verlag Leipzig-Mockrehna 2011. {{ISBN|3-940541-33-8}}.</ref> which finished the work on this topic at Leipzig. Thereafter, despite increased expenditures, the Berlin groups and their external branches did not succeed in getting a reactor critical until the end of World War II. However, this was realized by the Fermi group in December 1942, so that the German advantage was definitively lost, even with respect to research on energy production.

German historian [[Klaus Hentschel]] summarizes the organizational differences as:

:Compared with the British and American war research efforts united in the Manhattan Project, to this day the prime example of "big science," the Uranverein was only a loosely knit, decentralized network of researchers with quite different research agendas. Rather than teamwork as on the American end, on the German side we find cut-throat competition, personal rivalries, and fighting over the limited resources.{{sfn|Hentschel|Hentschel|1996|p=lxviii}}

The Manhattan Project's Alsos investigation ultimately concluded in a classified report, on the basis of documents and materials confiscated from research sites in Germany, Austria, and France, as well as interrogation of over 40 personnel connected with the program, that:

:The general plan of conducting the subject research [developing an atomic weapon] in some respects followed a pattern employed in the United States. Research assignments were farmed out to many small groups, generally of some university or technical school, or to industrial firms specializing in one or more of the related activities. However, the enemy effort was definitely lacking in overall direction, unity of purpose and coordination between participating agencies. Early in the German endeavor the uranium problem had been separately approached by a number of more or less competing groups. There was one group under Army Ordnance, another under the Kaiser-Wilhelm Institute for Physics, and still another under the Postal Department. A certain amount of bickering over the supply of material and a non-cooperative attitude in the exchange of information existed between those groups. The research efforts of the Postal Department amounted to little and did not continue for very long. The first two of the above groups were unified in 1942 under the Reich's Research Council. On the whole, beneficial results, from the German standpoint, were obtained through that unification. But conflicting jurisdiction between the German Government and Service branches still existed. Up until the later stages of the war difficulties were apparent in regard to the deferment of scientific personnel from military service. Many German scientists worked along their own lines and were not required to work at particular projects. Development of atomic weapon was not believed to be possible [during the war].

:As a consequence of the foregoing, atomic energy development in Germany did not pass beyond the laboratory stage; utilization for power production rather than for an explosive was the principal consideration; and, though German science was interested in this new field, other scientific objectives received greater official attention.<ref>{{cite web|title=Manhattan District History, Book 1, Volume 14, Foreign Intelligence Supplement No. 1|url=https://ia903409.us.archive.org/14/items/ManhattanDistrictHistory/MDH-B1V14P03-General-Intelligence_and_Security-Foreign_Intelligence_Supplement_1.pdf|page=S4.48|date=8 November 1948}}</ref>

In terms of financial and human resources, the comparisons between the Manhattan Project and the ''Uranverein'' are stark. The Manhattan Project consumed some US$2 billion (1945, ~US${{Inflation|US-GDP|2|1945}} billion in {{Inflation/year|US-GDP}} dollars) in government funds, and employed at its peak some 120,000 people, mostly in the sectors of construction and operations. In total the Manhattan Project involved the labor of some 500,000 people, nearly 1% of the entire US civilian labor force.<ref>{{cite web |url=http://blog.nuclearsecrecy.com/2013/11/01/many-people-worked-manhattan-project/ |title= How many people worked on the Manhattan Project? |publisher=Restricted Data Blog |date=1 November 2013 |access-date=16 November 2019 |last=Wellerstein |first=Alex |archive-url=https://web.archive.org/web/20190721043916/http://blog.nuclearsecrecy.com/2013/11/01/many-people-worked-manhattan-project// |archive-date=21 July 2019 |url-status=live}}</ref> By comparison, the ''Uranverein'' was budgeted a mere 8 million reichsmarks, equivalent to about US$2 million (1945,~US${{Inflation|US-GDP|2|1945}} million in {{Inflation/year|US-GDP}} dollars) – a thousandth of the American expenditure.{{sfn|Hentschel|Hentschel|1996|p=lxix}}<ref>The ''Uranverein'' budget in 1943/44 was 2.56 million RM, and 3.65 million RM in 1944/45. {{harvnb|Hentschel|Hentschel|1996|p=351 fn.23}}</ref>

==See also==
{{Portal|Germany|Nuclear technology}}
* [[Germany and weapons of mass destruction]]
* [[Japanese nuclear weapons program]]
* [[Alsos Mission]]
* [[Operation Paperclip]]

==Footnotes==
{{notelist}}

==References==
{{reflist|28em}}

===Sources===
{{Refbegin|30em}}
* {{cite book |last1=Ball |first1=Philip |author-link=Philip Ball |title=Serving the Reich: the struggle for the soul of physics under Hitler |date=2014 |location=Chicago |publisher=University of Chicago Press |isbn=978-0226204574
}}
* {{cite book |last=Bernstein |first=Jeremy |author-link=Jeremy Bernstein |date=2001 |title=Hitler's Uranium Club: The Secret Recordings at Farm Hall |publisher=Copernicus |isbn=0-387-95089-3
}}
* {{cite journal |last=Bernstein |first=Jeremy |date=2002 |title=Heisenberg and the critical mass |journal=Am. J. Phys. |volume=70 |issue=9 |pages=911–16
|doi=10.1119/1.1495409 |bibcode=2002AmJPh..70..911B }}
* {{cite journal |last=Bernstein |first=Jeremy |date=2004 |title=Heisenberg in Poland |journal=Am. J. Phys. |volume=72 |issue=3 |pages=300–04|doi=10.1119/1.1630333 |bibcode=2004AmJPh..72..300B }} See also ''Letters to the Editor'' by Klaus Gottstein and a reply by Jeremy Bernstein in ''Am. J. Phys.'' '''72''' (9): 1143–45 (2004).
* {{cite book |last=Beyerchen |first=Alan D. |date=1977 |title=Scientists Under Hitler: Politics and the Physics Community in the Third Reich |publisher=Yale |isbn=0-30001830-4
}}
* {{cite book |last=Cassidy |first=David C. |date=1992 |title=Uncertainty: The Life and Science of Werner Heisenberg |publisher=Freeman |url=https://en.wikipedia.org/wiki/Uncertainty_(book)
}}
* {{cite journal |last1=Crawford |first1=Elisabeth |last2=Sime |first2=Ruth Lewin |last3=Walker |first3=Mark |year=1997 |title=A Nobel Tale of Postwar Injustice |journal=Physics Today |volume=50 |issue=9 |pages=26–32
|doi=10.1063/1.881933 |bibcode=1997PhT....50i..26C }}
* {{cite book |editor-last= Ermenc |editor-first= Joseph J |title= Atomic Bomb Scientists: Memoirs, 1939–1945 |year= 1989 |publisher= Meckler |location= Westport, CT & London |isbn= 0-88736-267-2 }} (1967 interviews with Heisenberg, Harteck and others).
* {{cite journal |last=Gimbel |first=John |date=1986 |title=U.S. Policy and German Scientists: The Early Cold War |journal=Political Science Quarterly |volume=101 |issue=3
|pages=433–451 |doi=10.2307/2151624 |jstor=2151624 }}
* {{cite book |last=Gimbel |first=John |date=1990 |title=Science, Technology, and Reparations: Exploitation and Plunder in Postwar Germany |publisher=Stanford Press
}}
* {{cite book |last=Goudsmit |first=Samuel |year=1986 |title=Alsos |others=Introduction by [[Reginald Victor Jones|Reginald V. Jones]] |publisher=Toamsh
}}
* Hahn, Otto ''My Life'' (Herder and Herder, New York 1970)
* {{cite journal |last1=Hanle |first1=Wilhelm |author-link1=Wilhelm Hanle |last2=Rechenberg |first2=Helmut |author-link2=Helmut Rechenberg |year=1982 |title=1982: Jubiläumsjahr der Kernspaltungs¬forschung |journal=Physikalische Blätter |volume=38 |issue=12 |pages=365–67
|doi=10.1002/phbl.19820381207 |doi-access=free }}
* Heisenberg, Werner ''Research in Germany on the Technical Applications of Atomic Energy'', ''Nature'' Volume 160, Number 4059, 211–15 (16 August 1947). See also the annotated English translation: ''Document 115. Werner Heisenberg: Research in Germany on the Technical Application of Atomic Energy [16 August 1947]'' in {{harvnb|Hentschel|Hentschel|1996|pp=361–79}}.
* {{cite book |editor1-last=Hentschel |editor1-first=Klaus |editor2-last=Hentschel |editor2-first=Ann M. |translator-last=Hentschel |translator-first=Ann M. |year=1996 |title=Physics and National Socialism: An Anthology of Primary Sources |publisher=Birkhäuser |isbn=0-8176-5312-0 }} [This book is a collection of 121 primary German documents relating to physics under National Socialism. The documents have been translated and annotated, and there is a lengthy introduction to put them into perspective.]
* {{cite journal |last=Hentschel |first=Klaus |date=2020 |title=''Der neue Weg'': Mit inneratomarer Energie zum ''Herrn der Welt'' werden – Zu einem bislang unbekannten Typoskript vom Oktober 1944 (Inneratomic Energy as the ''New Path'' Towards Becoming ''Master of the World – On a Hitherto Unknown Typescript from October 1944'' |journal=NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin |volume=28
|issue=2 |pages=121–47 |doi=10.1007/s00048-020-00241-z |pmid=32415322 |doi-access=free }}
* Hoffmann, Klaus ''Otto Hahn – Achievement and Responsibility'' (Springer, New York. 2001) {{ISBN|0-387-95057-5}}
* {{cite journal |last=Hoffmann |first=Dieter |date=2005 |title=Between Autonomy and Accommodation: The German Physical Society during the Third Reich |journal=Physics in Perspective |volume=7 |issue=3
|pages=293–329 |doi=10.1007/s00016-004-0235-x |bibcode=2005PhP.....7..293H |s2cid=122355802 }}
* {{cite book |last=Kant |first=Horst |year=2002 |title=Werner Heisenberg and the German Uranium Project / Otto Hahn and the Declarations of Mainau and Göttingen |others=Preprint 203 |publisher=[[Max Planck Society|Max Planck Institute for the History of Science]] |url=http://www.mpiwg-berlin.mpg.de/Preprints/P203.PDF
}}
* {{cite journal |last=Landsman |first=Nicolaas P. |date=2002 |title=Getting even with Heisenberg |journal=Studies in History and Philosophy of Modern Physics |volume=33
|issue=2 |pages=297–325 |doi=10.1016/S1355-2198(02)00015-1 |url=http://philsci-archive.pitt.edu/9362/1/heisenberg.pdf }}
* {{cite book |last=Macrakis |first=Kristie |year=1993 |title=Surviving the Swastika: Scientific Research in Nazi Germany |publisher=Oxford University Press |isbn=0-19507010-0
}}
* {{cite book |last1=Mehra |first1=Jagdish |author-link1=Jagdish Mehra |last2=Rechenberg |first2=Helmut |author-link2=Helmut Rechenberg |year=2001 |chapter=The Conceptual Completion and Extensions of Quantum Mechanics 1932–1941. Epilogue: Aspects of the Further Development of Quantum Theory 1942–1999 |title=The Historical Development of Quantum Theory |volume=6-2 |publisher=Springer |isbn=978-038795086-0
}}
* {{cite book |last=Naimark |first=Norman M. |author-link=Norman Naimark |date=1995 |title=The Russians in Germany: A History of the Soviet Zone of Occupation, 1945–1949 |publisher=Belknap
}}
* {{cite book |last1=Riehl |first1=Nikolaus |author-link1=Nikolaus Riehl |last2=Seitz |first2=Frederick |author-link2=Frederick Seitz |year=1996 |title=Stalin's Captive: Nikolaus Riehl and the Soviet Race for the Bomb |publisher=American Chemical Society and the Chemical Heritage Foundations |isbn=0-84123310-1
}}
* {{cite journal |last=Oleynikov |first=Pavel V. |date=2000 |title=German Scientists in the Soviet Atomic Project |journal=The Nonproliferation Review |volume=7 |issue=2 |pages=1–30 |doi=10.1080/10736700008436807 |s2cid=144392252 |url=http://cns.miis.edu/npr/pdfs/72pavel.pdf }} The author has been a group leader at the Institute of Technical Physics of the Russian Federal Nuclear Center in [[Snezhinsk]] (Chelyabinsk-70).
* {{cite book |last=Powers |first=Thomas |date=1993 |title=Heisenberg's War: The Secret History of the German Bomb |publisher=Knopf
}}
* {{cite book |last1=Renneberg |first1=Monika |last2=Walker |first2=Mark |orig-year=1993 |year=2002 |title=Science, Technology and National Socialism |edition=first paperback |publisher=Cambridge Press
}}
* {{cite book |last=Sime |first=Ruth Lewin |author-link=Ruth Lewin Sime |year=1997 |title=Lise Meitner: A Life in Physics |publisher=University of California Press |isbn=978-0520208605
}}
* {{cite book |last=Sime |first=Ruth Lewin |author-link=Ruth Lewin Sime |year=2005 |chapter=From Exceptional Prominence to Prominent Exception: Lise Meitner at the Kaiser Wilhelm Institute for Chemistry (Ergebnisse 24) |title=Research Program "History of the Kaiser Wilhelm Society in the National Socialist Era" |institution=[[Max Planck Society|Max Planck Institute for the History of Science]] |chapter-url=http://www.mpiwg-berlin.mpg.de/KWG/Ergebnisse/Ergebnisse24.pdf
}}
* {{cite journal |last=Sime |first=Ruth Lewin |author-link=Ruth Lewin Sime |year=2006 |title=The Politics of Memory: Otto Hahn and the Third Reich  |journal=Physics in Perspective |volume=8 |issue=1 |pages=3–51
|doi=10.1007/s00016-004-0248-5 |bibcode=2006PhP.....8....3S |s2cid=119479637 }}
* {{cite book |last=Walker |first=Mark |year=1993 |title=German National Socialism and the Quest for Nuclear Power 1939–1949 |publisher=Cambridge Press  |isbn=0-52143804-7
}}
* {{cite book |last=Walker |first=Mark |year=1995 |title=Nazi Science: Myth, Truth, and the German Atomic Bomb |publisher=Perseus |isbn=0-30644941-2
}}
* {{cite book |last=Walker |first=Mark |year=2005 |chapter=Eine Waffenschmiede? Kernwaffen- und Reaktorforschung am Kaiser-Wilhelm-Institut für Physik (Ergebnisse 26) |title=Research Program "History of the Kaiser Wilhelm Society in the National Socialist Era" |institution=Max Planck Institute for the History of Science |chapter-url=http://www.mpiwg-berlin.mpg.de/KWG/Ergebnisse/Ergebnisse26.pdf
}}
{{refend}}

==Further reading==
{{Refbegin|30em}}
* Albrecht, Ulrich, Andreas Heinemann-Grüder, and Arend Wellmann ''Die Spezialisten: Deutsche Naturwissenschaftler und Techniker in der Sowjetunion nach 1945'' (Dietz, 1992, 2001) {{ISBN|3-320-01788-8}}
* {{cite journal |last1=Bernstein |first1=Jeremy |last2=Cassidy |first2=David |date=1995 |title=Bomb Apologetics: Farm Hall, August 1945 |journal=Physics Today |volume=48 |issue=8 Part 1 |pages=32–6
|doi=10.1063/1.881469 |bibcode=1995PhT....48h..32B }}
* Beyerchen, Alan ''What We Know About Nazism and Science'', ''Social Research'' Volume 59, Number 3, 615–641 (1992)
* {{Cite journal |last=Bethe |first=Hans A. |title=The German Uranium Project |journal=Physics Today |volume=53 |issue=7 |pages=34–6 |date=July 2000 |doi=10.1063/1.1292473 |url=http://www-personal.umich.edu/~sanders/214/other/news/Bethe.html|bibcode=2000PhT....53g..34B |url-access=subscription }}
* {{cite journal |last=Cassidy |first=David C. |date=1992 |title=Heisenberg, German Science, and the Third Reich |journal=Social Research |volume=59 |issue=3 |pages=643–61
}}
* Cassidy, David C. ''A Historical Perspective on Copenhagen'', ''Physics Today'' Volume 53, Issue 7, 28 (2000). See also ''Heisenberg's Message to Bohr: Who Knows'', ''Physics Today'' Volume 54, Issue 4, 14ff (2001), individual letters by Klaus Gottstein, Harry J. Lipkin, Donald C. Sachs, and David C. Cassidy.
* Eckert, Michael ''Werner Heisenberg: controversial scientist'' physicsweb.org [http://physicsworld.com/cws/article/print/3462 (2001)]
* {{cite book |editor-last=Ermenc |editor-first=Joseph J. |year=1989 |title=Atomic Bomb Scientists: Memoirs, 1939–1945 |location=Westport CT |publisher=Meckler |isbn=0-88736-267-2 |others=(1967 interviews with Werner Heisenberg and Paul Harteck) |ref=none}}
* Heisenberg, Werner ''Die theoretischen Grundlagen für die Energiegewinnung aus der Uranspaltung'', ''Zeitschrift für die gesamte Naturwissenschaft'', Volume 9, 201–212 (1943). See also the annotated English translation: ''Document 95. Werner Heisenberg. The Theoretical Basis for the Generation of Energy from Uranium Fission [26 February 1942]'' in {{harvnb|Hentschel|Hentschel|1996|pp=294–301}}.
* Heisenberg, Werner, introduction by David Cassidy, translation by William Sweet ''A Lecture on Bomb Physics: February 1942'', ''Physics Today'' Volume 48, Issue 8, Part I, 27–30 (1995)
* Hentschel, Klaus ''The Mental Aftermath: The Mentality of German Physicists 1945–1949'' (Oxford, 2007)
* Hoffmann, Dieter ''Zwischen Autonomie und Anpassung: Die deutsche physikalische Gesellschaft im dritten Reich'', ''Max-Planck-Institut für Wissenschafts Geschichte Preprint 192'' [http://www.mpiwg-berlin.mpg.de/Preprints/P192.PDF (2001)]
* Hoffmann, Dieter and Mark Walker ''The German Physical Society Under National Socialism'', ''Physics Today'' 57(12) 52–58 (2004)
* Hoffmann, Dieter and Mark Walker ''Zwischen Autonomie und Anpassung'', ''Physik Journal'' Volume 5, Number 3, 53–58 (2006)
* Hoffmann, Dieter and Mark Walker ''Peter Debye: "A Typical Scientist in an Untypical Time"'' Deutsche Physikalische Gesellschaft [https://web.archive.org/web/20070927011325/http://www.dpg-physik.de/gliederung/fv/gp/debye_en.html (2006)]
* Hoffmann, Dieter and Mark Walker (editors) ''Physiker zwischen Autonomie und Anpassung'' (Wiley-VCH, 2007)
* [[Rainer Karlsch|Karlsch Rainer]] ''Hitlers Bombe. Die geheime Geschichte der deutschen Kernwaffenversuche.'' (Dva, 2005)
* Karlsch, Rainer and Heiko Petermann ''Für und wider "Hitlers Bombe"'' (Waxmann, 2007)
* Krieger, Wolfgang ''The Germans and the Nuclear Question'' German Historical Institute Washington, D.C., Occasional Paper No. 14 (1995)
* [[Boris Pash|Pash, Boris T.]] ''The Alsos Mission'' (Award, 1969)
* [[Richard Rhodes|Rhodes, Richard]] ''The Making of the Atomic Bomb'' (Simon and Schuster, 1986)
* Rife, Patricia, ''Lise Meitner: Ein Leben fuer die Wissenschaft'' (Düsseldorf: Claassen, 1990).
* Rife, Patricia, ''Lise Meitner and the Dawn of the Nuclear Age'' (e-Book, Plunkett Lake Press, 2015) [https://plunkettlakepress.com/lm]
* Rose, Paul Lawrence, ''Heisenberg and the Nazi Atomic Bomb Project: A Study in German Culture'' (California, 1998). For a critical review of this book, please see {{harvnb|Landsman|2002|pp=297–325}}.
* Schaaf, Michael ''Heisenberg, Hitler und die Bombe. Gespraeche mit Zeitzeugen.'' (GNT-Verlag, 2018)
* Schumann, Erich ''Wehrmacht und Forschung'' in Richard Donnevert (editor) ''Wehrmacht und Partei'' second expanded edition, (Barth, 1939) 133–151. See also the annotated English translation: ''Document 75. Erich Schumann: Armed Forces and Research [1939]'' in {{harvnb|Hentschel|Hentschel|1996|pp=207–20}}.
* Walker, Mark ''National Socialism and German Physics'', ''Journal of Contemporary Physics'' Volume 24, 63–89 (1989)
* Walker, Mark ''Heisenberg, Goudsmit and the German Atomic Bomb'', ''Physics Today'' Volume 43, Issue 1, 52–60 (1990)
* Walker, Mark ''German Work on Nuclear Weapons'', ''Historia Scientiarum; International Journal for the History of Science Society of Japan'', Volume 14, Number 3, 164–181 (2005)
* Mark Walker ''Otto Hahn: Responsibility and Repression'', ''Physics in Perspective'' Volume 8, Number 2, 116–163 (2006). Mark Walker is Professor of History at Union College in Schenectady, New York.
{{Refend}}

==External links==
* [https://web.archive.org/web/20121021120546/http://www.nba.nbi.dk/papers/introduction.htm (February 2002) Aaserud, Finn ''Release of documents relating to 1941 Bohr-Heisenberg meeting'']
* [https://archive.today/20120526031212/http://nba.nbi.dk/release.html Niels Bohr Archive ''Release of documents relating to 1941 Bohr-Heisenberg meeting''] (6 February 2002)
* [https://web.archive.org/web/20170608004040/http://alsos.wlu.edu/qsearch.aspx?browse=warfare%2FGerman%20Atomic%20Bomb%20Program (June 2008) Annotated bibliography on the German atomic bomb project from the Alsos Digital Library for Nuclear Issues]
* Rife, Patricia, ''Lise Meitner and the Dawn of the Nuclear Age'' (Birkhauser/Springer Verlag, 1999)
* Walker, Mark [https://www.pbs.org/wgbh/nova/hydro/close.html ''Nazis & the Bomb''] from [[Public Broadcasting Service]] [[Nova (American TV series)|Nova]] episode, [https://www.pbs.org/wgbh/nova/hydro/ ''Hitler's Sunken Secret''] (originally aired 8 November 2005).
{{German nuclear energy project}}{{Military of Nazi Germany}}

{{DEFAULTSORT:German Nuclear Weapon Project}}
[[Category:Nuclear program of Nazi Germany| ]]
[[Category:Nuclear technology in Germany| ]]
[[Category:World War II weapons of Germany]]
[[Category:Nuclear weapons]]
[[Category:Nuclear weapons programs|Germany]]
[[Category:Nuclear history of Germany| ]]
[[Category:Abandoned projects of Nazi Germany]]