Conscription in the United States, commonly known as the draft, has been employed by the federal government in four 'conflicts': US Civil War; World War I; World War II; and the Cold War (including the Korean and Vietnam Wars). The third incarnation of the draft came into being in 1940 through the Selective Training and Service Act. It was the country's first peacetime draft. From 1940 until 1973, during both peacetime and periods of conflict, men were drafted to fill vacancies in the armed forces which could not be filled through voluntary means. The draft was ended when the United States military moved to an all-volunteer military force. However, the Selective Service System remains in place as a contingency plan; men between the ages of 18 and 25 are required to register so that a draft can be readily resumed if needed.