In 1959, Gary received a scholarship to Harvard and matriculated high school in 1960. In his junior year at Harvard he left to motorcycle in Europe, North Africa, and the Middle East before returning the following year. In 1964, he was deeply moved by the murders of Chaney, Goodman, and Schwerner in Philadelphia, Mississippi, and worked as a summer volunteer for the National Association for the Advancement of Colored People (NAACP) in Jackson, Mississippi, under the direction of Charles Evers, brother of the slain Medgar Evers. In 1965, he graduated from Harvard. That same year he enlisted in the U.S. Army and entered U.S. Army Infantry Officer Candidate School. He was commissioned as 2nd Lieutenant in 1966. He volunteered for the U.S. Army Special Forces (Green Berets), completed Parachute Training (Fort Benning, Georgia), U.S. Army Special Warfare School (Fort Bragg, North Carolina), and served as an A Detachment Executive Officer in Okinawa and Vietnam, participating in Top Secret operations in Vietnam and Laos. He left Vietnam after the Tet Offensive of January 1968 and was discharged from the U.S. Army in 1968 as 1st Lieutenant.