Second Lieutenant Allen was a member of the 9th Infantry Regiment, 2nd Infantry Division. He was Killed in Action while fighting the enemy along the Naktong Bulge near Yongsan, South Korea on 9 August 1950.

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.