General John T. Thompson, a graduate of West Point, began his research in 1915 for an automatic weapon to supply the American military. World War I was dragging on and casualties were mounting. Having served in the Army's ordnance supplies and logistics, General Thompson understood that greater firepower was needed to end the war.
Thompson was driven to create a lightweight, fully automatic firearm that would be effective against the contemporary machine gun. His idea was "a one-man, hand held machine gun. A trench broom!" The first shipment of Thompson prototypes arrived on the dock in New York for shipment to Europe on November 11, 1918, the day that the War ended.
In 1919, Thompson directed Auto Ordnance to modify the gun for nonmilitary use. The gun, classified a "submachine gun" to denote a small, hand-held, fully automatic firearm chambered for pistol ammunition, was officially named the "Thompson submachine gun" to honor the man most responsible for its creation.
With military and police sales low, Auto Ordnance sold its submachine guns through every legal outlet it could. A Thompson submachine gun could be purchased either by mail order, or from the local hardware or sporting goods store.