Private First Class Armentrout was a member of the Anti-Tank Company, 1st Marines, 1st Marine Division. He was seriously wounded while fighting the enemy in Korea and died of those wounds on 23 January 1952.

Armentrout was awarded the Purple Heart, the Combat Action Ribbon, 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.