Sergeant Clairmont was a member of Battery A, 555th Field Artillery Battalion, 5th Infantry Regimental Combat Team. He was taken Prisoner of War while fighting the enemy near Chongpyong ("Death Valley"), South Korea, on 25 April 1951 and died while a prisoner on 30 June 1951. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Clairmont was awarded the Combat Infantryman's Badge, the Prisoner of War Medal, 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.