First Sergeant Allen was a medic with the Medical Company, 9th Infantry Regiment, 2nd Infantry Division. He was taken Prisoner of War while tending his wounded comrades along the Chongchon River near Kunu-ri, North Korea on 1 December 1950 and died in a prison camp on 30 April 1951

Allen was awarded the Purple Heart, the Combat Medical 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.