The Thompson submachine gun, often referred to as the "Tommy Gun," is a .45 caliber submachine gun that was designed by John T. Thompson in the early 20th century. It became famous during the Prohibition era in the United States, used by both law enforcement and criminals. Its distinctive design features a wooden stock and a drum magazine, allowing for high-capacity fire. The Thompson was widely used during World War II and in various conflicts afterward. Its reliability and stopping power made it a favored weapon among soldiers and gangsters alike. The gun's iconic status has made it a symbol of the era, appearing in numerous films and media.