American Military History, Volume 2 by Richard W. Stewart

Although the Army made significant gains in retaining key person- nel, it could not depend upon voluntary enlistments to fill its need for manpower. In an emergency it could fall back upon its Ready and Standby Reserves, but neither force was available on a day-to-day basis. The Ready Reserve became available only when the President de- clared an emergency and only in numbers authorized by Congress. The Standby Reserve became liable for service only in a war or emergency declared by Congress itself. For all other needs, the Army had to rely on the draft, which Congress had enacted during the Korean War. It obligated all physically and mentally qualified males between the ages of eighteen and twenty-six to eight years of combined active and reserve military service.

There were several ways an eligible male could fulfill his obligation. By spending five of his eight years on active duty or in a combination of active duty and membership in the Ready Reserve, he could transfer to the Standby Reserve for his final three years. As an alternative, he might join the National Guard at the age of eighteen. By rendering satisfactory service for ten years, he would avoid active duty unless the President or Congress called his unit into federal service. A college student could meanwhile enroll in a Reserve Officer Training Corps (ROTC) course. This would allow him to spend two or three years on active duty and the remainder of his eight years as a reserve officer.