Tank origin

After World War II, which saw the heavy use of aircraft to attack ground forces, the U.S. invested in the development of self-propelled anti-aircraft guns. One such project was undertaken starting in 1955, when the U.S. began work on a Gatling-style gun capable of firing 37mm rounds. The resulting gun, dubbed the T250 Vigilante, featured six electronically rotated barrels and would become the largest rotary cannon built. It was mounted to the T249, a vehicle derived from the M113. The project was canceled in the 1960s in favor of developing missile-based systems.