On March 29, 1911, it was officially accepted as a regulation weapon of the US Armed Forces, initially receiving the name of .45 Caliber Semi-Automatic Pistol, M1911. Later from 1924, its designation changed to .45 Caliber Automatic Pistol, M1911A1. In total, the Army acquired about 2.7 million pistols during its lifetime of service.
It saw widespread use in World War I, World War II, the Korean War, and the Vietnam War. It remained in continuous service with the US Army until 1985, when it was succeeded by the Beretta. Some variants are still in production, given their popularity, still in use in some units of the US Special Forces, Navy and Marine Corps.