Private Vannoy was a member of the 24th Infantry Regiment, 25th Infantry Division. He was seriously wounded by the enemy in North Korea on 26 November 1950 and returned to duty on 13 December 1950. He was Killed in Action while fighting the enemy in South Korea on 9 March 1951.

Vannoy was awarded the Purple Heart with Oak Leaf Cluster, 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.