View source for M1 mortar

{{Infobox weapon
| name               = M1 mortar
| image              = "Members of a Negro mortar company of the 92nd Division pass the ammunition and heave it over at the Germans in an almos - NARA - 535546.jpg
| image_size         = 300
| caption            = [[G.I.]]'s of the  [[92nd Infantry Division (United States)|92nd Infantry Division]] fire an M1 mortar at [[Massa, Tuscany|Massa]] in Italy during [[World War II]].
| origin             = United States
| type               = [[Infantry mortar]]
<!-- Type selection -->| is_ranged          = yes
| is_bladed          = 
| is_explosive       = 
| is_artillery       = yes
| is_vehicle         = 
| is_missile         = 
| is_UK              = <!-- Service history -->
| service            = 1935–1952<ref name="Military Factory">{{cite web |title=Mortar, 81mm M1 81mm Medium Infantry Mortar (1935) |url=https://www.militaryfactory.com/smallarms/detail.php?smallarms_id=296 |website=Military Factory |publisher=MilitaryFactory.com |access-date=6 June 2021}}</ref>
| used_by            = United States<br>[[Vietnam]]<br>[[#Users|Other users]]
| wars               = [[World War II]]<br>[[Korean War]]<br>[[Algerian War]]<ref name ="Algeria">{{cite magazine|language=fr|magazine=Gazette des Armes |issue=220 |date=March 1992|title=L'armement français en A.F.N.|pages=12–16|url=http://fr.1001mags.com/parution/gazette-des-armes/numero-220-mars-1992/page-16-17-texte-integral|first=Jean|last=Huon}}</ref><br>[[Vietnam War]]<br>[[Nicaraguan Revolution]]<br>[[Salvadoran Civil War]]
<!-- Production history -->| designer           = 
| design_date        = 
| manufacturer       = 
| unit_cost          = 
| production_date    = 
| number             = 
| variants           = <!-- General specifications -->
| weight             = ''see general data''
| length             = {{convert|3|ft|11|in|m|abbr=on}}
| part_length        = 
| width              = 
| height             = 
| diameter           = 
| crew               = 8 (squad leader, gunner, assistant gunner, 5 ammunition bearers)
<!-- Ranged weapon  specifications -->| cartridge          = ''see ammunition''
| caliber            = {{convert|81|mm|in|abbr=on}}
| action             = 
| rate               = 18 rpm sustained<br>30-35 rpm maximum
| velocity           = {{convert|700|ft/s|m/s|abbr=on}}
| range              = 
| max_range          = {{convert|3300|yd|m|abbr=on}}
| feed               = 
| sights             = M4
<!-- Artillery specifications -->| breech             = 
| recoil             = 
| carriage           = 
| elevation          = 
| traverse           = 
}}

The '''M1 mortar''' is an American 81 millimeter [[caliber]] [[Mortar (weapon)|mortar]]. It was based on the [[Brandt Mle 27/31|French Brandt mortar]]. The M1 mortar was used from before [[World War II]] until the 1950s when it was replaced by the lighter and longer ranged [[M29 mortar]].

The [[PAVN|VPA]] used many M1 mortars captured from France (equipped by the US) and self-produced, equipped to battalions and regiments<ref>{{Cite web |title=Vũ khí Việt Nam trong hai cuộc kháng chiến. |url=https://www.quansuvn.net/index.php/topic,41.170.html |access-date=2025-06-06 |website=www.quansuvn.net}}</ref>.

==General data==
Weight:
*Tube 44.5 lb (20&nbsp;kg)
*Mount 46.5 lb (21&nbsp;kg)
*Base plate 45 lb (20&nbsp;kg)
**Total {{convert|136|lb|kg}}

==Ammunition==
*'''M43A1 light HE:''' 7.05&nbsp;lb (3.20&nbsp;kg); HE filling 1.22&nbsp;lb (0.55&nbsp;kg); range min 100&nbsp;yd (91&nbsp;m); range max 3300 yd (zone 7, 3018&nbsp;m); 80% frag radius 25&nbsp;yd (23&nbsp;m) (compared favorably with the 75&nbsp;mm howitzer). M52 superquick [[fuze]] (explode on surface).<ref>{{cite web|title=TM 9-1904|date=March 1944|url=https://www.bulletpicker.com/pdf/TM-9-1904.pdf#page=304|pages=302}}</ref>
*'''M43A1 light training:''' an empty version of the M43A1 light HE with an inert fuze. It was used as a training shell until it was replaced by the M68 training practice shell.
*'''M45 heavy HE:''' 15.10&nbsp;lb (6.85&nbsp;kg); HE filling 4.48&nbsp;lb (2.03&nbsp;kg); range max 1275&nbsp;yd (zone 5, 1166&nbsp;m); bursting radius comparable to the 105&nbsp;mm howitzer. Equipped with M45 (super quick/delay action selective) or M53 (delay action only) P.D. fuze.<ref>{{cite web|title=TM 9-1904|date=March 1944|url=https://www.bulletpicker.com/pdf/TM-9-1904.pdf#page=287|pages=285}}</ref><ref>{{cite web|title=TM 9-1904|date=March 1944|url=https://www.bulletpicker.com/pdf/TM-9-1904.pdf#page=304|pages=302}}</ref>
*'''M56 heavy HE:''' 10.77&nbsp;lb (4.86&nbsp;kg); HE filling 4.31&nbsp;lb (1.96&nbsp;kg); range max 2655&nbsp;yd (zone 5, 2428&nbsp;m), standard for issue and manufacture shell replacing M45.<ref>{{cite web|title=TM 9-1904|date=March 1944|url=https://www.bulletpicker.com/pdf/TM-9-1904.pdf#page=288|pages=286}}</ref> It used the M53 fuze back in 1944,<ref>{{cite web|title=TM 9-1904|date=March 1944|url=https://www.bulletpicker.com/pdf/TM-9-1904.pdf#page=304|pages=302}}</ref> but it was at some point replaced by the M77 Timed Super Quick (TSQ) fuze.
*'''M57 WP ([[White phosphorus (weapon)|white phosphorus]]) "bursting smoke":''' 10.74&nbsp;lb (4.87&nbsp;kg); range max 2470&nbsp;yd (2260&nbsp;m); designed to lay down screening smoke, but had definite anti-personnel and incendiary applications.
*'''M57 FS (a solution of [[sulfur trioxide]] in [[chlorosulfonic acid]]) chemical smoke:''' 10.74&nbsp;lb (4.87&nbsp;kg), range max 2470&nbsp;yd (2260&nbsp;m); laid down dense white fog consisting of small droplets of hydrochloric and sulfuric acids. In moderate concentrations, it is highly irritating to the eyes, nose, and skin.
*'''M68 training practice:''' 9.50&nbsp;lb to 10.10&nbsp;lb. An inert teardrop-shaped cast iron shell without provision for a fuze well that was used to simulate the M43 light HE shell. The casing on early models was painted black but post-World War 2 versions are painted blue. It came in 9 different weights (engraved on the shell) to allow it to simulate shell firing with and without booster charges. Weight zone one (9.5 lbs.) simulated a shell with the maximum of 8 booster charges and weight zone nine (10.10 lbs.) simulated the shell being fired without booster charges.
*'''M301 illuminating shell:''' range max 2200&nbsp;yd (2012&nbsp;m); attached to parachute; burned brightly (275,000 [[candela]]s) for about 60 seconds, illuminating an area of about 150 yards (137&nbsp;m) diameter. It used the M84 time fuze, which was adjustable from 5 to 25 seconds before priming charge detonated, releasing the illuminator and chute.

==Fuzes==
The M1 mortar's shells sometimes used the same fuzes as the shells for the M2 60 mm mortar. An adapter collar was added to the smaller fuzes to allow them to fit the larger shells.

*'''M43 mechanical timing (MT) fuze''': clockwork timed delay fuze. Models M43A5.
*'''M45 point detonating (PD) fuze''': selective fuze that could be set for time delay or super-quick (less than a second) detonation on impact. Replaced by the M52 and M53 fuzes.
*'''M48 point detonating (PD) fuze''': selective powder train burning fuze that can be set to super quick or delay ignition on impact. The factory pre-set delay time was stamped on the shell body. If the super-quick flash ignition failed, the delay fuse kicked in. If set on delay, the super-quick flash igniter mechanism was immobilized to prevent premature ignition. Models: M48, M48A1, M48A2 (either 0.05 or 0.15 second Delay), & M48A3 (0.05 second delay).
*'''M51 point detonating (PD) fuze''': selective powder train burning fuze that can be set to super quick or delay ignition after impact. It is a modification of the M48 fuze with the addition of a booster charge. Models: M51A4, M51A5 (M48A3 Fuze with M21A4 booster).
*'''M52 point detonating super-quick (PDSQ) fuze''': super-quick fuze that activates less than a second after impact. The pre-war M52 was made of aluminum, the M52B1 model was made of [[Bakelite]], and the M52B2 model had a Bakelite body and an aluminum head; the suffix would be added to the shell designation.
*'''M53 point detonating delay (PDD) fuze''': delay fuze that activates after impact.
*'''M54 time and super-quick (TSQ) fuze''': powder train burning fuze that can be set for time delay (slow burn) or super-quick (flash ignition) detonation on impact.
*'''M77 time and super quick (TSQ) fuze''': powder train burning fuze that can be set for time delay (slow burn) or super-quick (flash ignition) detonation on impact.
*'''M78 concrete penetrating (CP) fuze''': delay fuze that was set off after the shell had impacted and buried itself to increase the damage done.
*'''M84 mechanical timing (MT) fuze''': clockwork fuze that can be set from 0 to 25 seconds in 1-second intervals; seconds were indicated by vertical lines and 5-second intervals were indicated by metal bosses to allow it to be set in low-light or night-time conditions.
*'''M84A1 mechanical timing (MT) fuze''': clockwork fuze that can be set from 0 to 50 seconds in 2-second intervals.

== Users ==
It may be found in nearly all the non-Communist countries,<ref name="Janes 2002">{{cite encyclopedia|title=81mm M1 mortar|encyclopedia=Jane's Infantry Weapons 1994-1995|url=https://archive.org/details/Janes_Infantry_Weapons/page/n5683|pages=5684–5685|year=1994}}</ref> including:
{{div col}}
* {{flag|Austria}}: used on [[M21 mortar motor carriage]]<ref>{{cite web|title=Rearming Austria: WWII weapons|date=14 June 2015|url=https://wwiiafterwwii.wordpress.com/2015/06/14/rearming-austria-wwii-weapons/|website=wwiiafterwwii.wordpress.com}}</ref>
* {{flag|Belgium}}: made under license<ref name="Janes 2002"/>
*{{flag|Republic of China}}<ref name="Chinese">{{cite book|title=Kangzhan: Guide to Chinese Ground Forces 1937–45|publisher=Helion & Company |isbn=9781910294420|date=July 2016|url=https://books.google.com/books?id=ZYQwDwAAQBAJ&pg=PA346|first1=Leland|last1=Ness|first2=Bin|last2=Shih|page=346}}</ref>
* {{flag|Colombia}}<ref>{{cite encyclopedia|title=National inventories, Colombia|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n1601|page=1601|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Dominican Republic}}<ref>{{cite encyclopedia|title=National inventories, Dominican Republic|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n1509|page=1509|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
*{{flag|El Salvador}}
*{{flag|Ethiopia}}<ref name=IISS>{{cite book |last=[[International Institute for Strategic Studies]]|date=2021|title=The Military Balance|page=465|publisher=Taylor & Francis |isbn=9781032012278}}</ref>
*{{flag|France}}<ref name ="Algeria"/><ref>{{cite magazine|title=Le bataillon de Corée (1950/1953) |url=http://fr.1001mags.com/parution/gazette-des-armes/numero-227-novembre-1992/page-14-15-texte-integral|first=Michel|last=Rossi|issue=227|date=November 1992|pages=10–15|magazine=La Gazette des Armes|language=fr}}</ref>
*{{flag|Greece}}<ref name="Wiener 1987">{{cite book|title=The armies of the NATO nations: Organization, concept of war, weapons and equipment|series=Truppendienst Handbooks Volume 3|year= 1987|first=Friedrich |last=Wiener |page=468|publisher=Herold Publishers|location=Vienna}}</ref><ref>{{cite encyclopedia|title=National inventories, Greece|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n2344|page=2344|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Guatemala}}<ref>{{cite encyclopedia|title=National inventories, Guatemala|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n2359|page=2359|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Haiti}}<ref>{{cite web|title=Uphold Democracy 1994: WWII weapons encountered|date=9 June 2015|url= https://wwiiafterwwii.wordpress.com/2015/06/09/uphold-democracy-1994-wwii-weapons-encountered/|website= wwiiafterwwii.wordpress.com}}</ref><ref>{{cite encyclopedia|title=National inventories, Haiti|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n2363|page=2363|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Honduras}}<ref>{{cite encyclopedia|title=National inventories, Honduras|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n2363|page=2364|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Japan}}<ref>{{Cite book |author=Kenji Jyoshima |author2=Yusuke Tsuge |title=陸自車両50年史 (50 Years of JGSDF's Vehicles)  |publisher=Argonauts Publications |date=October 2007 |location=Tokyo, Japan |pages=126 |language=Japanese }}</ref>
* {{flag|Laos}}<ref>{{cite encyclopedia|title=National inventories, Laos|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n3086|page=3086|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Libya}}<ref>{{cite encyclopedia|title=National inventories, Libya|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n3090|page=3090|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{MEX}}<ref>{{cite encyclopedia|title=National inventories, Mexico|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n3105|page=3105|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|Myanmar}}:'''M-43'''<ref name="asiapacificdefencereporter.com">{{cite web|url=http://www.asiapacificdefencereporter.com/order-of-battle/myanmar|title=Myanmar|accessdate=29 November 2014|archive-url=https://web.archive.org/web/20141129025311/http://www.asiapacificdefencereporter.com/order-of-battle/myanmar|archive-date=29 November 2014|url-status=dead|df=dmy-all}}</ref><ref>{{cite book|isbn=978-981-230-848-1 |title=Building the Tatmadaw: Myanmar Armed Forces Since 1948|page=107|url=https://www.researchgate.net/publication/272092747|last=Maung|first= Aung Myoe|year=2009|publisher=Institute of Southeast Asian Studies }}</ref><ref>{{cite encyclopedia|title=National inventories, Myanmar (Burma)|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n3111|page=3112|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|South Korea}}: The [[Republic of Korea Armed Forces|Armed Forces]] was equipped with 386 M1s before the [[Korean War]], and 822 were in service with the [[Republic of Korea Army|Army]] by the end of the war. Began replacing with M29A1 or KM29A1 in 1970s.<ref>{{Cite book |last=Bak |first=Dongchan |url=http://medcmd.mil.kr/user/imhc/upload/pblictn/PBLICTNEBOOK_202105270240172800.pdf |title=Korean War : Weapons of the United Nations |publisher=Ministry of Defense Institute for Military History |date=March 2021 |isbn=979-11-5598-079-8 |location=Republic of Korea |pages=85–87 |language=Korean |access-date=2022-07-07 |archive-date=2022-09-20 |archive-url=https://web.archive.org/web/20220920170621/http://medcmd.mil.kr/user/imhc/upload/pblictn/PBLICTNEBOOK_202105270240172800.pdf |url-status=dead }}</ref>
* {{flag|Turkey}}<ref name="Wiener 1987"/>
* {{flag|Thailand}}{{cn|date=October 2019}}
* {{flag|United States}}
* {{flag|Uruguay}}<ref>{{cite encyclopedia|title=National inventories, Uruguay|encyclopedia=Jane's Infantry Weapons 2001-2002|url=https://archive.org/details/Janes_Infantry_Weapons/page/n5797|page=5797|date=22 November 2000|first1=Terry J.|last1=Gander}}</ref>
* {{flag|South Vietnam}}<ref>{{cite book|title=Army of the Republic of Vietnam 1955–75|url=https://archive.org/details/armyrepublicviet00rott|url-access=limited|publisher=[[Osprey Publishing]]|first=Gordon L. |last=Rottman|series=Men at Arms 458 |date=2010|page=[https://archive.org/details/armyrepublicviet00rott/page/n45 9]|isbn=9781849081818}}</ref>
* {{flag|North Vietnam}}
* {{flag|Vietnam}}<ref name ="NVA">{{cite book|title=North Vietnamese Army Soldier 1958–75|series=Warrior 135|first=Gordon L. |last=Rottman|date= 10 Feb 2009|publisher=[[Osprey Publishing]]|isbn=9781846033711|url=https://books.google.com/books?id=iC21CwAAQBAJ|page=32}}</ref>
{{div col end}}

==See also==
* [[M2 Mortar]]
* [[List of U.S. Army weapons by supply catalog designation]] SNL A-33
* [[M3 Half-track]]

===Weapons of comparable role, performance and era===
* [[Ordnance ML 3 inch Mortar]] British equivalent
* [[8 cm Granatwerfer 34]] German equivalent

==References==
{{reflist}}
* FM 23-90
* TM 9-1260
* SNL A-33

== External links ==
{{Commons category|81 mm Mortar M1}}
* [http://www.90thidpg.us/Equipment/Weapons/index.html 90th Infantry Division Preservation Group] - page on 81&nbsp;mm mortars and equipment
* [https://books.google.com/books?id=_yYDAAAAMBAJ&dq=popular+science+june+1941&pg=PA118 ''Popular Science'', August 1943, ''Pill Boxes Destroyer''] article on M1 81mm mortar

{{WWIIUSGuns}}

[[Category:Infantry mortars]]
[[Category:World War II infantry weapons of the United States]]
[[Category:World War II mortars]]
[[Category:Mortars of the United States]]
[[Category:Chemical weapons of the United States]]
[[Category:Chemical weapon delivery systems]]
[[Category:81mm mortars]]
[[Category:Military equipment introduced in the 1930s]]