Allen was the flight engineer of a B-25C bomber assigned to the 11th Bombardment Squadron. On June 3, 1942 he took part in a flight of six B-25s from Dinjan, India to attack Lashio, Burma and then proceed over the Himalayas to a base in Kunming, China. The raid on Lashio was successful and the flight withdrew on course to Kunming at 10,000 feet in a thick overcast. Suddenly, Allen's and two other planes crashed into the side of a mountain. The others barely missed hitting the ground after pulling up sharply.
Allen was from Warren County IL, he received the Air Medal and the Purple Heart.
Because his body was not recovered, he is memorialized on the Tablets of the Missing.