Thompson submachine gun
First weapon marketed as a submachine gun.
The Thompson submachine gun—nicknamed the "Tommy gun," "Chicago typewriter," or "trench broom"—is a blowback-operated, selective-fire weapon invented by U.S. Army Brigadier General John T. Thompson in 1918. It was meant to overcome the deadlock of World War I trench warfare, but early versions missed combat. It holds the distinction of being the first firearm marketed as a "submachine gun."
Thompson, an ordnance officer, originally wanted a fully automatic rifle to replace bolt-action service rifles like the M1903 Springfield. In 1915, he found a patent by John Bell Blish for a lock that relied on the adhesion of inclined metal surfaces under pressure. With backing from businessman Thomas F. Ryan, Thompson founded the Auto-Ordnance Company in 1916 to develop his "auto rifle." The weapon was mainly designed in Cleveland, Ohio, by Theodore H. Eickhoff, Oscar V. Payne, and George E. Goll. By late 1917, the Blish lock proved to be a friction-delayed blowback system rather than a locked breech, and the only suitable cartridge was the .45 ACP. Thompson envisioned a hand-held machine gun chambered in .45 ACP as a "trench broom" for World War I. Payne designed the firearm and its stick and drum magazines under the project name "Annihilator I." Most design issues were solved by 1918, but the war ended two days before prototypes could be shipped to Europe.
In 1919, after the war, the weapon was renamed the "Thompson Submachine Gun" at an Auto-Ordnance board meeting. Thompson intended it to deliver high-volume automatic fire for trench warfare, a role the Browning Automatic Rifle (BAR) had not filled well. German troops had already used the Bergmann MP 18, the world's first submachine gun, with their stormtrooper tactics.
The first production model was the Model of 1921. It was sold to civilians but sold poorly due to its high price—$200 in 1921 (about $3,610 in 2025). Early complaints included its heavy weight, inaccuracy beyond 50 yards (46 m), and the .45 ACP cartridge's lack of penetrating power. The Thompson first saw combat on June 13, 1921, when West Virginia state troopers fired at a mountainside near Lick Creek where striking miners were shooting at cars. By the Battle of Blair Mountain, state police had 37 Thompsons, while coal companies and local law enforcement had 56. Guns were also shipped to regional hardware stores.
Quick Facts
- Origin
- United States
- Is Ranged
- yes
- Service
- 1921–present
- Designer
- John T. Thompson
- Design Date
- 1917–1920
- Production Date
- 1921–1945
- Weight
- 10.8 lb empty (Thompson M1928A1) / 10 lb empty (Thompson M1A1)
- Length
- 33.7 in (M1928A1 with compensator) / 31.9 in (M1/M1A1)
- Part Length
- 10.52 in / 12 in (with Cutts compensator)
- Cartridge
- .45 ACP (11.43×23mm) / 10mm Auto (limited quantity of FBI conversions)
Facts from the source article.
Lore & Background
The Thompson was developed primarily in Cleveland, Ohio, with principal designers Theodore H. Eickhoff, Oscar V. Payne, and George E. Goll. Thompson came across a patent issued to John Bell Blish in 1915 while searching for a way to allow his weapon to operate safely without the complexity of a recoil or gas-operated reloading mechanism. The Blish lock was based on the supposed adhesion of inclined metal surfaces under pressure. By late 1917, the limits of the Blish lock were discovered, and the weapon was instead designed to function as a friction-delayed blowback action. It was found that the only cartridge then in service suitable for use with the new lock was the .45 ACP. Oscar V. Payne designed the firearm along with its stick and drum magazines. The project was titled "Annihilator I". Most design issues had been resolved by 1918, but the war ended two days before prototypes could be shipped to Europe.
The first Thompson entered production as the Model of 1921. It was available to civilians but initially saw poor sales due to its high price. The Thompson was first used in combat on 13 June 1921, when West Virginia state troopers fired on a mountainside near Lick Creek where striking miners were firing at passing cars. Some of the first batches were bought by agents of the Irish Republican Army. The Thompson achieved early notoriety in the hands of Prohibition and Great Depression-era gangsters and the lawmen who pursued them, and was depicted in gangster films. It saw early use by the United States Marine Corps during the Banana Wars, the United States Postal Inspection Service, the Irish Republican Army, and the Republic of China. The FBI adopted the Thompson following the 1933 Kansas City massacre.
Reader's Guide
The Thompson submachine gun holds a significant place in both military and cultural history. It was widely adopted by the U.S. armed forces during World War II and used extensively by other Allied troops, with more than 1.5 million produced during that conflict. Its main models were the M1928A1, M1, and M1A1. The weapon became notorious during the Prohibition era as the signature weapon of organized crime syndicates in the United States in the 1920s, while also being used by law enforcement. It was a common sight in media at the time. The original selective-fire Thompson variants are no longer produced, but numerous semi-automatic civilian versions are still being produced by Auto-Ordnance. These models retain a similar appearance but have modifications to comply with US firearm laws. The Thompson's legacy includes its role in the Banana Wars, its use by the Irish Republican Army, and its adoption by the FBI after the Kansas City massacre. It was also used by Nationalist China against Japanese forces, and local copies were produced by Chinese arsenals such as Taiyuan Arsenal.
Did You Know?
- The Thompson was first used in combat on 13 June 1921 by West Virginia state troopers against striking miners.
- It was the first weapon to be labeled and marketed as a 'submachine gun'.
- The original price of a Thompson in 1921 was $200, equivalent to roughly $3,610 in 2025.
- The FBI adopted the Thompson after the 1933 Kansas City massacre.
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