Gallagher attended Pennsylvania State University after graduating from Olney High School in 1963, and worked as a short-order cook for the Horn & Hardart's chain. He enlisted in the Marine Corps in November 1967 and married a month later. The 20-year-old lance corporal, a rifleman. was sent to Vietnam in June 1968 and assigned to Company K of the 3rd Battalion, 1st Marines, 1st Marine Division. He died Jan. 21, 1969, in Quang Nam Province. Gallagher was survived by his wife, parents, three brothers and several sisters