Sergeant Allen was a member of the 9th Infantry Regiment, 2nd Infantry Division. He was seriously Wounded in Action by the enemy along the Chongchon River near Kunu-ri, North Korea on 30 November 1950 and died of those wounds on 12 January 1951.

Allen was awarded the Purple Heart, 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.