Private First Class De Manno was a member of the 31st Infantry Regiment, 7th Infantry Division. He was Killed in Action while fighting the enemy in the "Iron Triangle" area of North Korea on 31 October 1952.

De Manno was awarded the Purple Heart with Oak Leaf Cluster, the Combat Infantryman's Badge, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation, the Republic of Korea War Service Medal and the Army of Occupation Medal (Japan).