The Battle of Khe Sanh was conducted in Khe Sanh of northwestern Quảng Trị Province, Republic of Vietnam (South Vietnam), between 21 January and 9 July 1968 during the Vietnam War. The belligerent parties were elements of the United States III Marine Amphibious Force (III MAF), 1st Cavalry Division, the US Seventh Air Force, 1st Battalion 9th Marine Regiment, minor elements of the South Vietnamese Army (ARVN) against two to three division-size elements of the People's Army of Vietnam (generally referred to in Western sources as the North Vietnamese Army or NVA).
The American command in Saigon initially believed that combat operations around the Khe Sanh Combat Base (KSCB) during the summer of 1967 were just part of a series of minor North Vietnamese offensives in the border regions. That appraisal was altered when it was discovered that the NVA was moving major forces into the area during the autumn and winter. A build-up of US Marine Corps forces took place and actions around Khe Sanh commenced when the Marine base was isolated. During a series of desperate actions that lasted 5 months and 18 days, Khe Sanh Combat Base and the hilltop outposts around it were under constant North Vietnamese ground, artillery, mortar, and rocket attacks.
During the battle, a massive aerial bombardment campaign (Operation Niagara) was launched by the United States Air Force to support the Marine base. Over 100,000 tons of bombs were dropped until mid-April by aircraft of the Air Force, US Navy and Marines onto the area surrounding Khe Sanh. This was roughly 1,300 tons of bombs dropped daily–five tons for every one of the 20,000 NVA soldiers initially estimated to have been committed to the fighting at Khe Sanh. In addition, 158,000 large-caliber shells were fired on the hills surrounding the base. This expenditure of aerial munitions dwarfs the amount of munitions fired by artillery, which totals eight shells per NVA soldier believed to have been on the battlefield. The campaign used the latest technological advances in order to locate NVA forces for targeting. The logistical effort to support KSCB, once it was isolated overland, demanded the implementation of other tactical innovations in order to keep the Marines supplied.