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 military 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 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.