American Marines arrived at Chu Lai, South Vietnam in May 1965. Over the next several months, the Marines not only engaged the enemy in brutal combat, but also had to contend with the harsh climate and rough terrain, which took its toll on the men physically and mentally. The inexperienced Marines, who were mostly teenagers, engaged the enemy troops, known as the Viet Cong, who had been fighting South Vietnamese forces for 20 years. Over the next three months, the Marines fought Viet Cong insurgents near the airbase. On August 18, two battalions of marines, including the third battalion, third marines, engaged the First Viet Cong regiment in the first major battle of the Vietnam War between American forces and communist troops. The brutal five-day operation, known as Starlite, was a major victory for the Marines.