This is the second volume of nine chronological histories covering the Marine Corps' participation in the Vietnam War. This volume details the Marine activities during 1965, the year the war escalated and major American combat units were committed to the conflict. The narrative traces the landing of the nearly 5,000-man 9th Marine Expeditionary Brigade and its transformation into the III Marine Amphibious Force, which by the end of the year contained over 38,000 Marines.