Corporal Dunn was a member of Company A, 1st Battalion, 19th Infantry Regiment, 24th Infantry Division. He was taken Prisoner of War while fighting the enemy in South Korea on 16 July 1950, forced to march to North Korea on the "Tiger Death March" and died as a prisoner at the "Cornfield" near Manpo, North Korea, on 27 October 1950. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Dunn was awarded the Purple Heart, the Combat Infantryman's Badge, the Prisoner of War Medal, the Good Conduct Ribbon, the Combat Infantryman's Badge, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal and the Korean War Service Medal.