13. Marine basic training changed during the course of the war
In 1964, the United States Marine Corps operated two recruit training depots. New recruits who enlisted in locations west of the Mississippi River (with some exceptions based on location) were sent to San Diego. The rest went to Parris Island, near Beaufort, South Carolina. In 1964, just prior to the escalation of American troop levels in Vietnam, both depots adopted the same training programs. In the early 1960s the length of basic training was 13 weeks, three of which were concentrated on marksmanship training, using the venerable M-14 rifle. Later in the Vietnam era it was shortened to 9 weeks, and the M-14 was gradually replaced with the M-16, the main infantry rifle in the war zone.
In March, 1966, Parris Island alone was populated with over 10,000 new Marines. Over 200,000 graduated from the recruit depot over the course of American involvement in Vietnam. In 1971, as American troop levels deployed in Vietnam were steadily decreasing, Individual Combat Training (ICT) was added to the curriculum, and recruits were shipped to Camp Lejeune for field training. Recruits were trained to bivouac in the field, techniques of infantry combat, concealment, and other skills which were required for survival in the field.