At which South Vietnamese air base did US Marines land in March 1965?

US Marines landed at Da Nang Air Base in March 1965. On March 8, the 1st Battalion, 3rd Marines arrived at the base from Naha Air Base in Okinawa as part of the first US combat deployment to South Vietnam.

The landing took place alongside an amphibious arrival by the 9th Marine Regiment at Red Beach, north of Da Nang. The Marines were assigned to protect the important air base, while the Army of the Republic of Vietnam retained overall responsibility for defending the wider Da Nang area. Their arrival marked a major escalation from the earlier US advisory mission.

Da Nang was strategically important because it supported air operations and lay near the northern edge of South Vietnam, close to the demilitarized zone. The base soon became a major Marine aviation hub. In April, Marine fighter-bomber and tactical air-control units also deployed there.

Cam Ranh Bay, Tan Son Nhut, and Bien Hoa were important South Vietnamese bases, but none is the canonical answer to this question. The March 1965 Marine landing is specifically linked to Da Nang Air Base and the nearby Red Beach.