Private First Class Thomas was a member of Company G, 2nd Battalion, 9th Infantry Regiment, 2nd Infantry Division. He was seriously wounded by the enemy in South Korea on 8 September 1950 and returned to duty on 13 October 1950. He was Killed in Action while fighting the enemy in North Korea on 26 November 1950. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Thomas 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.