The Last Great American Freedom Machine 1921 T-Shirt

The Thompson submachine gun (also known as the "Tommy Gun", "Chicago Typewriter", "Chicago Piano", or "Trench Broom") is a blowback-operated, air-cooled, magazine-fed selective-fire submachine gun, invented by the United States Army Brigadier general John T. Thompson in 1918. It was originally designed to break the stalemate of trench warfare of World War I, but was not finished until after the war ended. It is the first weapon to be labeled and marketed as a "submachine gun" and became notorious during the Prohibition era, used as a signature weapon of various organized crime syndicates in the United States in the 1920s. It was a common sight in the media at the time as it was used by both law enforcement officers and criminals.