Corporal Allen was a medic with the Medical Company, 9th Infantry Regiment, 2nd Infantry Division. He was Killed in Action while tending his wounded comrades along "Heartbreak Ridge" in North Korea on 10 October 1951.

Allen was awarded the Purple Heart, the Combat Medical 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.