Major Gier was the pilot of a F4U-5 Corsair fighter with Marine Fighter Squadron 212, Marine Air Group 33, 1st Marine Air Wing. On March 21, 1951, while on a combat mission, his aircraft received a direct hit by anti-aircraft fire and he was forced to ditch the aircraft in enemy territory. Efforts to rescue him were thwarted by enemy small arms fire. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.