Editing Thompson submachine gun (section)

==History and service==
[[File:Thompson-and-his-gun.jpg|thumb|left|upright=0.8|Brigadier General [[John T. Thompson]] holding a Model 1919 Thompson]]

===Development===
[[Brigadier General (United States)|Brigadier General]] [[John T. Thompson]], who spent most of his career in the ordnance department of the [[United States Army|U.S. Army]], was the original inventor and developer of the Thompson submachine gun. He envisioned it as being a fully [[Thompson Autorifle|automatic rifle]] in order to replace the [[bolt-action]] service rifles then in use (such as the American [[M1903 Springfield]]).

Thompson came across a patent issued to the American inventor [[John Bell Blish]] in 1915, while searching for a way to allow his weapon to operate safely without the complexity of a [[Recoil operation|recoil]] or [[gas-operated reloading]] mechanism. Blish's design (then known as the [[Blish lock]]) was based on the supposed adhesion of inclined metal surfaces under pressure.<ref>{{cite book |last=Hatcher |first=Julian S. |title=Hatcher's Notebook |publisher= Military Service Publishing Co. |year=1947 |page=44}}</ref> Thompson gained financial backing from the businessman [[Thomas Fortune Ryan|Thomas F. Ryan]] and proceeded to found a company, which he named the [[Auto-Ordnance Company]], in 1916, for the purpose of developing his new "auto rifle".

The Thompson was primarily developed in [[Cleveland, Ohio]].<ref>{{cite web |title=The Unofficial Tommy Gun Page |url=http://www.nfatoys.com/tsmg/ |website=www.nfatoys.com |access-date=2004-02-22 |archive-date=2002-10-14 |archive-url=https://web.archive.org/web/20021014034546/http://www.nfatoys.com/tsmg/ |url-status=dead }}</ref> Its principal designers were Theodore H. Eickhoff, Oscar V. Payne, and George E. Goll. By late 1917, the limits of the Blish lock were discovered (which is essentially an extreme manifestation of [[static friction]]), and, rather than the firearm working as a locked breech, the weapon was instead designed to function as a friction-delayed [[Blowback (arms)|blowback]] action. It was found that the only cartridge then in service suitable for use with the new lock was the [[.45 ACP]]. General Thompson envisioned a "one-man, hand-held machine gun" chambered in .45 ACP to be used as a "trench broom" for the ongoing [[trench warfare]] of [[World War I]].{{Sfn|Pegler|2010|p=9}} Oscar V. Payne designed the new firearm along with its stick and drum magazines. The project was titled "Annihilator I". Most of the design issues had been resolved by 1918; however, the war ended two days before prototypes could be shipped to Europe.<ref name="Frank Iannamico 1928">{{harvnb|Iannamico|2000|page={{page needed|date=December 2011}}}}</ref>

At an Auto-Ordnance board meeting in 1919, in order to discuss the marketing of the "Annihilator", with the war now over the weapon was officially renamed the "Thompson Submachine Gun". While other weapons had been developed shortly prior with similar objectives in mind, the Thompson was the first weapon to be labeled and marketed as a "submachine gun".<ref name="James"/> Thompson intended for the weapon to provide a high volume of automatic, man-portable fire for use in trench warfare—a role for which the [[M1918 Browning Automatic Rifle|Browning Automatic Rifle]] (BAR) had been determined ill-suited.{{sfn|Fitzsimons|1977|p=272}} The concept had already been developed by German troops using their own Bergmann [[MP 18]] (the world's first submachine gun) in concert with their {{lang|de|[[infiltration tactics|Sturmtruppen]]}} tactics.<ref>{{cite book|last=Gudmundsson|first=Bruce I.|year=1995|title=Stormtroop Tactics: Innovation in the German Army, 1914–1918|publisher=Praeger Press|isbn=0275954013}}{{page needed|date=December 2011}}</ref>

===Early use===
[[File:Joseph McCarty, circa 1930 (17505960029).jpg|left|thumb|upright|[[United States Marine Corps|US Marine]] holding an M1928 Thompson during the [[Banana Wars]]]]

The first Thompson entered production as the Model of 1921. It was available to civilians, but, because of the weapon's high price, initially saw poor sales. The Thompson (with one Type XX 20 round "stick" magazine) had been priced at $200 in 1921 (roughly {{Inflation|US|200|1921|fmt=eq|r=-1}}{{Inflation/fn|US}})

The major initial complaints concerning the Thompson were its cumbersome weight, its inaccuracy at ranges over {{convert|50|yd|m}}, and its lack of penetrating power using the .45 ACP cartridge.<ref name="rt66.com">{{cite web |first=Bert |last=Kortegaard |url=http://www.rt66.com/~korteng/SmallArms/thompson.htm |title=M1A1 Thompson Submachine Gun |publisher=Rt66.com |date=2000-09-21 |access-date=2011-12-25 |url-status=dead |archive-url=https://web.archive.org/web/20111217064700/http://www.rt66.com/~korteng/smallarms/thompson.htm |archive-date=2011-12-17}}</ref>

The Thompson was first used in combat in 13 June 1921, when West Virginia state troopers fired on the mountainside near Lick Creek, where striking miners were firing at passing cars. By the time of the [[Battle of Blair Mountain]], 37 had been acquired by the West Virginia state police and 56 were in the hands of coal companies and local law enforcement. The guns were also shipped to various hardware stores in the region.<ref>{{Cite magazine |last=Association |first=National Rifle |title=Guns of the Battle of Blair Mountain |url=https://www.americanrifleman.org/content/guns-of-the-battle-of-blair-mountain/ |access-date=2022-12-02 |magazine=American Rifleman |publisher=National Rifle Association |language=en}}</ref>

Some of the first batches of Thompsons were bought (in America) by agents of the [[Irish Republican Army]] (notably the Irish gunman [[Harry Boland]]). The first test of the Thompson in Ireland was performed by Irish Republican Army unit commander [[Tom Barry (Irish republican)|Tom Barry]], of the [[3rd Cork Brigade|West Cork Brigade]], in the presence of IRA leader [[Michael Collins (Irish leader)|Michael Collins]].<ref>{{cite book|last=Ryan|first= Meda |year=2003|title=Tom Barry: IRA Freedom Fighter|publisher= Mercier Press|page= 125 |isbn=1-85635-425-3}}</ref> They purchased a total of 653 units, though US customs authorities in New York seized 495 of the units in June 1921. The remainder found their way to the Irish Republican Army by way of Liverpool, England, and were used in the last month of the [[Irish War of Independence]] (1919–1921).{{sfn|Hart|2003|pp=184–185}} After a ceasefire called by the British in July 1921, the Irish Republican Army imported more units, which were used in the subsequent [[Irish Civil War]] (1922–1923). The Thompson was not found to be very effective in Ireland, it was not conducive to terrorist actions, having only caused serious casualties in 32 percent of the incidents in which it was used.<ref name="Hart, p. 187–188" />

During the failed [[1924 Estonian coup d'état attempt|1924 Estonian coup]], communists used Thompsons in an attempt to storm the Tallinn barracks; meanwhile the [[MP 18]] was used by the defenders. This was possibly the first engagement where submachine guns were used on both sides.<ref name=":0" />

The Thompson achieved early notoriety in the hands of [[Prohibition in the United States|Prohibition]] and [[Great Depression]]-era gangsters and the lawmen who pursued them. It was also depicted in [[gangster film]]s during this era, most notably regarding the [[Saint Valentine's Day Massacre]]. The Thompson guns used in the massacre are still being held by the Berrien County Sheriff's Department.<ref>{{cite news|title=St. Valentine's Day Massacre: Tale of two guns|first1=Brent|last1=Ashcroft|url=https://www.abc10.com/article/news/local/st-valentines-day-massacre-tale-of-two-guns/103-41411998|work=ABC 10 News}}</ref> The Thompson has been referred to by one researcher as the "gun that made the [[Roaring Twenties|twenties roar]]".<ref name="NMAH">{{cite web|url=http://americanhistory.si.edu/collections/object.cfm?key=35&objkey=126|title=Thompson Model 1928 Submachine Gun|publisher=National Museum of American History, Smithsonian Institution|access-date=2008-06-12}}</ref><ref>{{cite book|first=William J. |last=Helmer|title=The Gun That Made the Twenties Roar|publisher=MacMillan|year=1969|isbn=978-0-02-550890-3|page={{page needed|date=December 2011}}}}</ref>

Around 200 Model of 1921 Thompsons were sold in 1926 to the [[United States Postal Inspection Service]]<ref>{{cite web |url=http://www.postalmuseum.si.edu/inspectors/a6p1.html |website=Smithsonian National Postal Museum |archive-url=https://web.archive.org/web/20070611180052/http://www.postalmuseum.si.edu/inspectors/a6p1.html|archive-date=2007-06-11 |title=Postal Inspectors: The Silent Service: Unexpected Duties |quote=The Postal Inspection Service became the first law enforcement agency to purchase the Thompson submachine gun&nbsp;...}}</ref><ref name=":1">{{Cite web |last=McCollum |first=Ian |date=2018-10-09 |title=The Marines' First SMG: 1921/28 Thompson Gun |url=https://www.forgottenweapons.com/the-marines-first-smg-1921-28-thompson-gun/ |access-date=2023-08-20 |website=Forgotten Weapons |language=en-US}}</ref><ref name=":2">{{Cite web |title=Marines Guard the US Mail 1921 |url=https://marines.togetherweserved.com/usmc/newsletter/38/Marines%20Guard%20the%20US%20Mail%201921.html |access-date=2023-08-20 |website=marines.togetherweserved.com}}</ref>{{failed verification|reason=Source doesn't mention weapons of any kind. Mentions robberies but remember what this article is about|date=May 2024}} so they could protect the mail from a spate of robberies.<ref name="Fitz2487">{{harvnb|Fitzsimons|1977|p=2487}}</ref> These weapons were loaned to the United States Marine Corps which was, at that time, tasked with guarding mail shipments; this prompted the US Navy to formally test the Thompson. The Navy requested a reduction in the rate of fire. Auto-Ordnance complied, modifying the weapons by adding a substantial amount of mass to the actuator.<ref>{{Cite web |last=Stilwell |first=Blake |date=2022-06-10 |title=The intense rules for US Marines who protected mail from gangsters |url=https://www.wearethemighty.com/popular/intense-rules-for-marine-guards/ |access-date=2023-08-20 |website=We Are The Mighty |language=en}}</ref><ref name=":2" /> In 1927 a number of Thompsons would be shipped to Marines in [[China Marines|China]] and [[Nicaragua]].<ref name="schroeder1927" /><ref>{{Cite magazine |last=Association |first=National Rifle |title=Guns of the 'Banana Wars' Part Two |url=https://www.americanrifleman.org/content/guns-of-the-banana-wars-part-two/ |access-date=2023-08-23 |magazine=American Rifleman |publisher=National Rifle Association |language=en}}</ref> The Navy subsequently ordered 500 guns, designated the Model of 1928.<ref name=":1" />  

The Thompson saw popularity as a point-defense weapon for countering ambushes by Nicaraguan guerrillas (in the [[Banana Wars]]) and led to the creation of four-man [[fire team]]s which had as much firepower as a nine-man rifle squad. Federal sales were then followed by sales to police departments in the US, as well as to various international armies and constabulary forces; chiefly in Central and South America.<ref name="Fitz2487" />

In 1926, the Cutts compensator (a [[muzzle brake]]) was offered as an attachment option for the Thompson. Models with the compensator were cataloged as ''No. 21AC'', at the original price of $200. The plain Thompson (without the attachment) was designated ''No. 21A'' at a reduced price of $175<ref name="Frank Iannamico 1928"/> (roughly {{Inflation|US|175|1926|fmt=eq|r=-1}}{{Inflation/fn|US}}).

In 1928, [[Federal Laboratories]] took over distribution of the weapon from Thompson's Auto-Ordnance Corporation.<ref name="ramsour">{{cite magazine |first=Robert "Bo" II |last=Ramsour |title=The FBI and the Thompson Submachine Gun |magazine=Soldier of Fortune |date=18 July 2010}}{{page needed|date=December 2011}}</ref> The new cost was listed as $225 per weapon ({{Inflation|US|225|1928|fmt=eq}}{{Inflation/fn|US}}), with ammunition sold at $5 per 50-round drum and $3 per 20-round magazine.<ref name="ramsour"/>

Thompsons had also been widely used throughout China, where several Chinese warlords and their military factions [[Warlord Era|running various parts of the fragmented country]] made purchases of the weapon, and subsequently produced many local copies.

[[File:Corporal, East Surrey Regiment 1940.jpg|thumb|A British soldier equipped with a Thompson M1928 submachine gun in November 1940]]
[[Republic of China (1912–1949)|Nationalist China]] acquired a substantial number of Thompson guns for use against Japanese land forces. They began producing copies of the Thompson in small quantities for use by their armies and militias. In the 1930s, [[Taiyuan Arsenal]] (a Chinese weapons manufacturer) produced copies of the Thompson for [[Yan Xishan]], the then  warlord of [[Shanxi]] province.

The FBI had also acquired Thompsons in 1933 following the [[Kansas City Massacre]].<ref name="ramsour"/>

A number of these guns were acquired by a construction company in Brazil,{{Who|date=September 2022}} after construction of a federal road in Sergipe was disrupted by armed [[Cangaceiros|Cangaçeiros]] in December 1937 who violently opposed any attempts to build roads near their territory.<ref>{{Cite book |last=de Mello |first=Frederico Pernambucano |date=2011 |title=Guerreiros do sol : violência e banditismo no Nordeste do Brasil |language=pt-BR |trans-title=Sun Warriors: violence and banditry in Northeast Brazil|edition=5th revised and updated |publisher=A Girafa |location=São Paulo |pages=332 |isbn=978-85-63610-05-8 |oclc=879852051}}</ref>

===World War II===
In 1938, the Thompson submachine gun was adopted by the [[Military of the United States|U.S. military]] and was used during [[World War II]].

There were two military types of Thompson submachine gun:

* The '''M1928A1''', which had provisions for both box and drum magazines, utilized the Cutts muzzle brake, had cooling fins on the [[Gun barrel|barrel]], and employed a delayed blowback action with the charging handle on the top of the receiver.
* The '''M1''' and '''M1A1''', which had provisions for box magazines only, did not have cooling fins on the barrel, had a simplified rear sight, and employed a straight blowback action with the charging handle on the side of the receiver.

Over 1.5 million military Thompson submachine guns were produced during World War II.<ref name="Iannamico 1999"/>

====Magazine developments====
[[File:Thompson Magazine.JPG|thumb|Drum and box magazines]]
Military users of the M1928A1 units had complaints of the "L" 50-round drum magazine. The [[British Army during the Second World War|British Army]] criticized "the [magazine's] excessive weight, [and] the rattling sound they made" and shipped thousands back to the U.S. in exchange for 20-round box magazines. The Thompson had to be cocked, bolt retracted, ready to fire, in order to attach the drum magazine. The drum magazine also attached and detached by sliding sideways, which made magazine changes slow and cumbersome. They also created difficulty when clearing a cartridge malfunction ("jam"). Reloading an empty drum with cartridges was a difficult and involved process in which the 50 rounds would be inserted and then the magazine wound up until a minimum of 9 to 11 loud "clicks" were heard before seating the magazine into the weapon.

In contrast, the "XX" twenty-round box magazine was light and compact. It tended not to rattle, and could be inserted with the bolt safely closed. The box magazine was quickly attached and detached, and was removed downward, making clearing jams easier. The box magazine tripped the bolt open lock when empty, facilitating magazine changes. An empty box was easy to reload with loose rounds. However, users complained that it was limited in capacity. In the field, some soldiers would tape two "XX" magazines together, in what would be known as [[Jungle style (firearm magazines)|"jungle style"]], to quicken magazine changes.<ref name="Thompson">{{cite magazine|url=http://www.americanrifleman.org/articles/2011/2/15/thompson-submachine-gun-the-tommy-gun-goes-to-war/|title=Thompson Submachine Gun: The Tommy Gun Goes to War|access-date=2016-02-04|magazine=American Rifleman|first=Bruce|last=Canfield|publisher=National Rifle Association}}</ref>

Two alternatives to the "L" 50-round drum and "XX" 20-round box magazines were tested 6 December 1941, at [[Fort Knox|Fort Knox, Kentucky]]. An extended thirty-round box magazine and a forty-round magazine, which were made by welding two 20-round magazines face to face, jungle style, were tested. The testers considered both superior to either the "XX" box or "L" drum. The 30-round box was approved as the new standard in December 1941 to replace the "XX" and "L" magazines.{{sfn|Iannamico|2000|pp=161, 173, 175}} (The concept of welding two box magazines face-to-face was also carried over to the [[United Defense M42|M42]] submachine gun.)

====M1 development====
The staff of [[Savage Arms]] looked for ways to simplify the M1928A1, and produced a prototype in February 1942, which was tested at Aberdeen Proving Ground in March 1942. Army Ordnance approved adoption (as the M1) in April 1942. M1s were made by [[Savage Arms]] and by [[Auto-Ordnance Company|Auto-Ordnance]]. M1s were issued with the 30-round box magazine and would accept the earlier 20-round box, but would not accept the drum magazine.{{sfn|Iannamico|2000|pp=94–97}}

====Combat use====
[[File:Ww2 158.jpg|thumb|A [[United States Marine Corps|U.S. Marine]] fires on a Japanese position using an M1 Thompson submachine gun during an [[Battle of Okinawa|advance on Okinawa]] in May 1945.]]
The Thompson was used in World War II in the hands of [[Allies of World War II|Allied]] troops as a weapon for scouts, [[non-commissioned officer]]s ([[corporal]], [[sergeant]], and higher), and [[patrol]] leaders, as well as commissioned officers, tank crewmen, and soldiers performing raids on German positions. In the European theater, the gun was widely utilized in [[British Army|British]] and [[Canadian Army|Canadian]] [[British Commandos|commando]] units, as well as in the [[United States Army|U.S. Army]] [[paratrooper]] and [[United States Army Rangers|Ranger]] [[battalion]]s, where it was issued more frequently than in [[line infantry]] units because of its high rate of fire and its stopping power, which made it very effective in the kinds of close combat these [[special operations]] troops were expected to undertake. [[Military Police]] were fond of it, as were paratroopers, who "borrowed" Thompsons from members of mortar squads for use on patrols behind enemy lines.<ref>[[David Kenyon Webster|Webster, David K.]] ''Parachute Infantry'' <!--publisher, place, & date?-->{{page needed|date=August 2015}}</ref> The gun was prized by those lucky enough to get one and proved itself in the close street fighting that was encountered frequently during the invasion of France. A Swedish variant of the M1928A1, the {{lang|sv|Kulsprutepistol m/40}} (machine pistol, model 40), served in the [[Swedish Army]] between 1940 and 1951. Through [[Lend-Lease Act|Lend-Lease]], the [[Soviet Union]] also received the Thompson, but due to a shortage of appropriate ammunition, its use was not widespread.<ref>{{Cite book|last= Bishop |first= Chris |title= The Encyclopedia of Weapons of World War II |place= New York |publisher= Orbis |year= 1998 |isbn= 978-0-7607-1022-7 }}{{page needed|date=December 2011}}</ref>

In the [[Malayan Campaign]], the [[Burma Campaign]] and the [[Asiatic-Pacific Theater|Pacific Theater]], Lend-Lease-issue Thompsons were used by the [[British Army]], [[Indian Army during World War II|Indian Army]], [[Australian Army]] [[infantry]] and other [[Commonwealth of Nations|Commonwealth]] forces. They used the Thompson extensively in jungle patrols and ambushes, where it was prized for its firepower, though it was criticized for its hefty weight and poor reliability. In New Guinea, the Thompson was the only submachine gun available to the Australian Army for most of the vital [[Kokoda Track campaign]] in 1942. It became so prized that soldiers routinely picked up Thompson guns dropped by killed or wounded comrades. However, the weight of the ammunition and difficulties in supply eventually led to its replacement in Australian Army units in 1943 by Australian-made submachine guns, the [[Owen Gun|Owen]] and [[Austen MK I|Austen]].<ref>{{cite journal |last=Moremon |first=John |year=2022 |title=The Tommy Gun in Jungle Warfare: The Use and Usefulness of the Thompson Submachine Gun for Australian Soldiers on the Kokoda Trail, New Guinea, 1942 |journal=Vulcan: The Journal of the History of Military Technology |volume=9 |issue=1 |pages=84–117 |doi=10.1163/22134603-09010005}}</ref> Thompsons were also given to the [[Royal Australian Air Force]] and [[Royal Australian Navy]].

In Burma and India, British forces largely replaced the Thompson with the [[Sten gun]]. New Zealand commando forces in the South Pacific campaign initially used Thompsons but switched them for the more reliable, lighter, and more accurate Owen during the [[Solomon Islands]] and [[Guadalcanal]] campaigns.<ref>{{cite web|url=http://nzetc.victoria.ac.nz/tm/scholarly/tei-WH2IP-Comm-t1-body1-d13.html|title=Chapter XII – Guadalcanal – NZETC|website=nzetc.victoria.ac.nz}}</ref> The U.S. Marines also used the Thompson as a limited-issue weapon, especially during their later island assaults. The Thompson was soon found to have limited effect in heavy jungle cover, where the low-[[Muzzle velocity|velocity]] .45 bullet would not penetrate most small-diameter trees or protective armor vests. {{anchor|Remington-Thompson}}(In 1923, the Army had rejected the [[.45 Remington–Thompson]], which had twice the energy of the .45 ACP.){{sfn|Bearse|1994|p=213}} In the U.S. Army, many Pacific War jungle patrols were originally equipped with Thompsons in the early phases of the [[New Guinea]] and [[Guadalcanal]] campaigns, but soon began employing the [[Browning Automatic Rifle]] in its place as a point defense weapon.{{sfn|George|1981|p=400}}

The Army introduced the U.S. [[M3 submachine gun|M3]] and M3A1 submachine guns in 1943 with plans to produce the latter in numbers sufficient to cancel future orders for the Thompson, while gradually withdrawing it from first-line service. However, due to unforeseen production delays and requests for modifications, the M3/M3A1 never replaced the Thompson, and purchases continued until February 1944. Though the M3 was considerably cheaper to produce, at the end of World War II, the Thompson, with a total wartime production of over 1.5 million, outnumbered the M3/M3A1 submachine guns in service by nearly three to one.<ref name="Iannamico 1999">{{cite book|last=Iannamico|first=Frank|title=The U.S. M3–M3A1 Submachine Gun|location=Harmony, Maine|publisher= Moose Lake |isbn=978-0-9701954-4-9|year=1999| pages= 14, 55}}</ref>

===After World War II===
{{more citations needed|section|date=January 2018}}
[[File:Mandelbaum Gate Jerusalem.jpg|thumb|Two Israeli policemen armed with Thompsons meet a Jordanian legionnaire near the [[Mandelbaum Gate]] {{circa|1950}}]]

Thompson submachine guns were used by both sides during the [[1948 Arab-Israeli war]].{{sfn|Yenne|2009|p=263}} Following the war, Thompsons were issued to members of Israel's elite [[Unit 101]], upon the formation of that unit in 1953.<ref name="Eilam">{{cite book|last= Uzi|first= Eilam|title= Eilam's Arc: How Israel Became a Military Technology Powerhouse|publisher= Sussex Academic Press|year= 2011|page=7}}</ref>

During the [[Greek Civil War]], the Thompson submachine gun was used by both sides. The [[Hellenic Armed Forces]], gendarmerie and police units were equipped with Thompson submachine guns supplied by the British and later in the war by the United States. The opposing Communist fighters of the [[Democratic Army of Greece]] were also using Thompson submachine guns, either captured from government forces or inherited from [[Greek People's Liberation Army|ELAS]]. ELAS was the strongest of the resistance forces during the period of [[Greek Resistance]] against the Germans and Italians and were supplied with arms from both the British and the United States. After the demobilization of ELAS, an unspecified number of arms were not surrendered to the government but kept hidden and were later used by the Democratic Army of Greece.<ref name="Sazanidis">{{harvnb|Sazanidis|1995|pp=293–295}}</ref>

The Thompson also found service with the [[Royal Netherlands East Indies Army|KNIL]] and the [[Netherlands Marine Corps]] during their [[Indonesian National Revolution|attempt]] to retake their former colony of Indonesia.<ref name="ArmsControl">{{cite book|title=The Control of local conflict : a design study on arms control and limited war in the developing areas|volume=3|last1=Bloomfield|first1= Lincoln P.|last2=Leiss|first2=Amelia Catherine|last3=Legere|first3= Laurence J.|last4= Barringer|first4= Richard E.|last5=Fisher|first5= R. Lucas|last6= Hoagland|first6= John H.|last7=Fraser|first7= Janet|last8=Ramers|first8=Robert K.|publisher=Center for International Studies, Massachusetts Institute of Technology|url=https://apps.dtic.mil/sti/pdfs/ADA324492.pdf#page=86|archive-url=https://web.archive.org/web/20200804022404/https://apps.dtic.mil/sti/pdfs/ADA324492.pdf#page=86|url-status=live|archive-date=4 August 2020|date=30 June 1967|hdl=2027/uiug.30112064404368|pages=81, 89|ref={{SfnRef|Bloomfield|Leiss|1967}} }}</ref> The gun was used by Indonesian infiltrators during the 1965 [[Indonesia–Malaysia confrontation]].{{sfn|Bloomfield|Leiss|1967|p=191}}

By the time of the [[Korean War]] in 1950, the Thompson had seen much use by the U.S. and South Korean military, even though the Thompson had been replaced as standard-issue by the M3/M3A1. With huge numbers of guns available in army ordnance arsenals, the Thompson remained classed as Limited Standard or Substitute Standard long after the standardization of the M3/M3A1. Many Thompsons were distributed to the US-backed Nationalist Chinese armed forces as military aid before the fall of [[Chiang Kai-shek]]'s government to [[Mao Zedong]]'s communist forces at the end of the [[Chinese Civil War]] in 1949 (Thompsons had already been widely used throughout China since the 1920s, at a time when several Chinese warlords and their military factions running various parts of the fragmented country made purchases of the weapon and then subsequently produced many local copies). During the Korean War, US troops were surprised to encounter [[People's Volunteer Army|communist Chinese troops]] armed with Thompsons (amongst other captured US-made Nationalist Chinese and American firearms), especially during unexpected night-time assaults which became a prominent Chinese combat tactic in the conflict. The gun's ability to deliver large quantities of short-range automatic assault fire proved very useful in both defense and assault during the early part of the war when it was constantly mobile and shifting back and forth. Many Chinese Thompsons were captured and placed into service with American soldiers and marines for the remaining period of the war.

The [[Yugoslav People's Army|Yugoslav Army]] received 34,000 M1A1 Thompsons during the 1950s as part of a US Military Aid to Yugoslavia Agreement. These guns were used during the [[Yugoslav Wars]] in the 1990s.<ref name="Yugoslav Army">{{cite book|title=Yugoslavia and After: A Study in Fragmentation, Despair and Rebirth|first1=David A. |last1=Dyker |first2= Ivan |last2= Vejvoda|edition=1st|date= 9 December 1996|location= London|publisher= Routledge|isbn= 9781317891352 |page=120|url=https://books.google.com/books?id=7VmPBAAAQBAJ&pg=PT169}}</ref>

During the [[Cuban Revolution]], the Thompson submachine gun was used by both [[Fulgencio Batista|Batista]]'s army and [[Fidel Castro]]'s guerrillas. Both the latter and the [[Brigade 2506]] also used some during the [[Bay of Pigs Invasion]].<ref name="Cuba">{{cite book|title=The Bay of Pigs: Cuba 1961|series = Elite 166|first=Alejandro |last=de Quesada |date=10 January 2009|isbn=9781846033230|url=https://books.google.com/books?id=EE-1CwAAQBAJ|pages= 9, 60–61}}</ref>

During the [[Vietnam War]], some [[Army of the Republic of Vietnam|South Vietnamese army]] units and defense [[militia]] were armed with Thompson submachine guns, and a few of these weapons were used by reconnaissance units, advisors, and other American troops. It was partially replaced by the [[MAC-10]], albeit during Vietnam, the fully automatic fire provided by the [[M16 rifle|M16]] made the Thompson less effective than it previously had been. Still, not only did some U.S. soldiers have use of them in Vietnam, they encountered them as well. The [[Viet Cong]] liked the weapon and used both captured models as well as manufacturing their own copies in small jungle workshops.<ref>{{cite web|url=http://www.williammaloney.com/Aviation/WestPointMilitaryMuseum/SubmachineGuns/pages/12VietCongHomemadeThompsonSubmachineGun.htm|title=12 Viet Cong Homemade Thompson Submachine Gun|website=www.williammaloney.com|access-date=2018-05-13|archive-date=2019-01-18|archive-url=https://web.archive.org/web/20190118074643/http://www.williammaloney.com/Aviation/WestPointMilitaryMuseum/SubmachineGuns/pages/12VietCongHomemadeThompsonSubmachineGun.htm|url-status=dead}}</ref>

The Australian government destroyed most of their Thompson machine carbines in the 1960s. They shipped their remaining stocks to arm the forces of [[Lon Nol]]'s [[Khmer Republic]] in 1975. They were then captured and used by the [[Khmer Rouge]].{{cn|date=December 2023}}

During [[the Troubles]] (1969–1998), the Thompson was again used by the Irish Republican paramilitaries. According to historian [[Peter Hart (historian)|Peter Hart]], "The Thompson remained a key part of both the [[Official IRA]] and [[Provisional IRA]] arsenals until well into the 1970s when it was superseded by the [[Armalite AR-18|Armalite]] and the [[AK-47]]."{{sfn|Hart|2003|p=191}}

The Thompson was also used by U.S. and overseas law enforcement and police forces, most prominently by the [[Federal Bureau of Investigation|FBI]]. The FBI used Thompsons until they were declared obsolete and ordered destroyed in the early 1970s.<ref>{{cite magazine|last=Vanderpool|first=Bill|title=Bring Enough Gun|magazine=[[American Rifleman]]|publisher=National Rifle Association|date= October 2013 |pages=80–85&115–116}}</ref>