Seized and activated by the U.S. Marines a year earlier, the base, which had been an old French outpost, was used as a staging area for forward patrols and was a potential launch point for contemplated future operations to cut the Ho Chi Minh Trail in Laos.
The battle began on this date with a brisk firefight involving the 3rd Battalion, 26th Marines and a North Vietnamese battalion entrenched between two hills northwest of the base. The next day North Vietnamese forces overran the village of Khe Sanh and North Vietnamese long-range artillery opened fire on the base itself, hitting its main ammunition dump and detonating 1,500 tons of explosives.
An incessant barrage kept Khe Sanh’s Marine defenders pinned down in their trenches and bunkers. Because the base had to be resupplied by air, the American high command was reluctant to put in any more troops and drafted a battle plan calling for massive artillery and airstrikes.
During the 66-day siege, U.S. planes, dropping 5,000 bombs daily, exploded the equivalent of five Hiroshima-sized atomic bombs in the area. The relief of Khe Sanh, called Operation Pegasus, began in early April as the 1st Cavalry (Airmobile) and a South Vietnamese battalion approached the base from the east and south, while the Marines pushed westward to re-open Route 9.
The siege was finally lifted on April 6 when the cavalrymen linked up with the 9th Marines south of the Khe Sanh airstrip. In a final clash a week later, the 3rd Battalion, 26th Marines drove enemy forces from Hill 881 North. Gen. William Westmoreland, commander of U.S. Military Assistance Command Vietnam, contended that Khe Sanh played a vital blocking role at the western end of the DMZ, and asserted that if the base had fallen, North Vietnamese forces could have outflanked Marine defenses along the buffer zone.
Various statements in the North Vietnamese Communist Party newspaper suggested that Hanoi saw the battle as an opportunity to re-enact its famous victory at Dien Bien Phu, when the communists had defeated the French in a climactic decisive battle that effectively ended the war between France and the Viet Minh.