The Thompson is an American submachine gun, invented by John T. Thompson in 1919 that became infamous during the Prohibition era. It was a common sight of the time, being used by both law enforcement officers and criminals. The Thompson was also known informally as: the "Tommy Gun", the "Trench Broom", the "Trench Sweeper", the "Chicago Piano", the "Chicago Typewriter", and the "Chopper".
The Thompson first entered production as the M1921. It was available to civilians, though its high price resulted in few sales. (A Thompson M1921 with one Type XX 20 shot "stick" magazine was priced at $200.00 when a Ford automobile sold for $400.00.) M1921 Thompsons were sold in small quantities to the United States Marine Corps (despite the lore that the United States Postal Service-U.S. Post Office- purchased this initial batch of 250 Colt Thompson Submachine Guns from the Auto Ordnance Corporation to protect the mail from a spate of robberies the AOC records and the USMC Quartermaster procurement records do not support this contention), followed by several police departments in the United States and minor international sales to various armies and constabulary forces, chiefly in Central and South America. .The Marines put their Thompson Submachine Guns to use in the Banana Wars and in China. It was popular with the Marines as a point-defense weapon for countering ambush by Nicaraguan guerrillas and led to the organisation of 4 man fire teams with as much firepower as a 9 man rifle squad. The major complaints against the Thompson were its weight, inaccuracy at ranges over 50 yards, and its lack of penetrating power, despite the powerful round it used.
In 1938, the Thompson submachine gun was adopted by the U.S. military, serving during World War II and beyond.
There were two military types of Thompson SMG. The M1928A1 had provisions for box magazines and drums (the drums were disliked because of their tendency to rattle and jam). It had a Cutts compensator, cooling fins on the barrel, and its charging handle was on the top of the receiver. The M1 and M1A1 had a barrel without cooling fins, a simplified rear sight, provisions only for box magazines, and the charging handle was on the side of the receiver. Because the option to use drums was not included in the M1 and M1A1, the 30 round box magazine was designed for use with this model.
The Thompson was used in World War II in the hands of Allied troops as a weapon for scouts, non-commissioned officers (corporal, sergeant and higher ranking), and patrol leaders. In the European theater, the gun was widely utilized in British and Canadian Commando units, as well as U.S. paratrooper and Ranger battalions who used it widely because of its high rate of fire, its stopping power and because it was very effective in close combat. A Swedish variant of the M1928A1, called Kulsprutepistol m/40 (meaning "submachine gun model 40"), served in the Swedish Army between 1940 and 1951. Through Lend-Lease, the Soviet Union also received the Thompson, but due to a shortage of appropriate ammunition in the Soviet Union, usage was not widespread.
In the Pacific Theater, Australian Army infantry and other Commonwealth forces initially used the Thompson extensively in jungle patrols and ambushes, where it was prized for its firepower, though its hefty weight of over 10 pounds and difficulties in supply eventually led to its replacement by other submachine guns such as the Owen and Austen. 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-velocity .45 bullet would not penetrate most small-diameter trees, or protective armor vests (in 1923, the Army had rejected the .45 Remington-Thompson, which had twice the energy of the .45ACP). 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 BAR in its place, especially at front (point) and rear (tail) positions, as a point defense weapon. The Argentine company Hafdasa and the Buenos Aires based firm Halcon manufactured the C-4 and M-1943 submachine guns which have a very similar layout and performance to the Thompson Gun, both weapons chambered in 9x19mm for the Argentine Army and .45 ACP for the Argentine Police forces. These weapons were a serious contender to the Thompson Gun but did not see much service outside Argentina.
Thanks to Wikipaedia