Thompson submachine gun or "Tommy Gun" is an iconic weapon of the second quarter of the 20th century. It was developed in the last days of World War I. The war ended before the first prototypes could be sent to Europe, but after Thompson M1921 mass-produced, the criminals of Chicago and New York liked him. With the entry of the United States into World War II, it was urgently necessary to equip and arm combat units and the Thompson submachine gun began his career as part of the US Army. He became a favorite weapon for groups of British commandos, during their sorties behind enemy lines.