What 1965 US Marine operation was the first major purely American offensive action of the war?

The 1965 US Marine operation that was the first major purely American offensive action of the war was Operation Starlite.

Fought from August 18 to 24, 1965, near Van Tuong in South Vietnam, Starlite was planned after intelligence revealed that the Viet Cong 1st Regiment was preparing to attack the Marine base at Chu Lai. Lieutenant General Lewis W. Walt chose to strike first. More than 5,000 Marines used a coordinated amphibious landing, helicopter assault, ground advance, artillery, aircraft and naval gunfire.

The operation became a turning point because it was the first major offensive of regimental size conducted solely by US military forces. It also demonstrated how American firepower and mobility could be combined in a search-and-destroy mission. The Marines reported heavy Viet Cong losses, although wartime casualty figures were disputed and both sides claimed success.

The battle is also known as the Battle of Van Tuong. “Starlite” was reportedly a field change from the original codename “Satellite,” after a power blackout caused a clerk working by candlelight to misread or retype the name.