Corporal Garrison was a member of Company E, 2nd Battalion, 8th Cavalry Regiment, 1st Cavalry Division. He was seriously wounded by the enemy in South Korea on 4 September 1950 and returned to duty on 16 September 1950. He was seriously wounded again and taken Prisoner of War near Unsan, North Korea on 2 November 1950, and died while a prisoner on 31 December 1950. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Garrison was awarded the Purple Heart with Oak Leaf Cluster, the Prisoner of War Medal, the Combat Infantryman's 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.