Private First Class Greenleaf was a member of Company F, 2nd Battalion, 23rd Infantry Regiment, 2nd Infantry Division. He was listed as Missing in Action while fighting the enemy in North Korea on 18 July 1952. He was presumed dead on 31 December 1953. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Greenleaf was awarded the Purple Heart, the Combat Infantryman Badge, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.