Corporal Day was a member of Company C, 1st Battalion, 32nd Infantry Regiment, 7th Infantry Division. He was listed as Missing in Action while fighting the enemy in North Korea on December 2, 1950. He was presumed dead on December 31, 1953. His name is permanently inscribed on the Courts of the Missing at the Honolulu Memorial. CPL Day's remains were recovered and then identified in 2014.