Corporal Castonguay was a member of the 21st Infantry Regiment, 24th Infantry Division. He was seriously wounded by the enemy in North Korea on 29 May 1951 and returned to duty on 22 June 1951. He was Killed in Action while fighting the enemy in North Korea on 13 July 1951.

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