For most of its history, the United States used a draft—a process of involuntary military conscription—to fill out the ranks of the U.S. armed forces during times of war. The first peacetime draft was enacted on September 16, 1940, when President Franklin D. Roosevelt signed into law the Selective Training and Service Act, which required all men between the ages of 21 and 45 to register. After World War II, the U.S. government reinstated the peacetime draft, which lasted from 1948 to 1973, a period of heightened Cold War tensions that included the Korean War and the Vietnam War.
The draft came under fire in the late 1960s when hundreds of thousands of young people each year were conscripted to fight the war in Vietnam. Richard Nixon, campaigning for the 1968 presidential election, promised that he would end the draft if elected. In 1971, President Nixon signed legislation authorizing the end of the draft but later extended it for two more years. The very last draftees reported for duty on June 30, 1973.