Auto Colt Pistol. Developed by John Browning in 1905 and adopted by the United States Ordinance Department, with the Colt-Browning automatic pistol, in 1911, it has also been made the official military handgun calibre by several other governments. The 45 was replaced in 1985 as the official military handgun cartridge by the 9mm Parabellum.
Found on http://www.encyclo.co.uk/local/20524