The Siege of Khe Sanh

U.S. battles of the war in Vietnam had young GIs or Marines humping into the boonies in search of the enemy. A smaller slice of the action saw Americans on the receiving end, defending some firebase or outpost.

The United States and its South Vietnamese allies pulled many huge offensive operations that boiled down to combat at the retail level: small-unit actions of ambush or assault with Americans piling on reinforcements and firepower to smite adversaries who, often as not, remained invisible or obscure. The North Vietnamese and Liberation Front adversaries – whether defending positions against an offensive, counterattacking an outpost or lying in ambush – fought as long as they considered desirable, and then faded away.

Only a handful of times in the Vietnam War did the adversary come out in force for an offensive battle. One such episode took place in 1968, in the context of the Tet Offensive. Tet is remembered for attacks all over South Vietnam, but most of those engagements were over in just a few days. Khe Sanh was the only battle of the war in which the adversary took the offensive and sustained the attack for an extended period – more than two months. The allied entrenched camp was threatened and put under siege in a campaign punctuated by a series of North Vietnamese assaults on its key positions. What was it all about?

Khe Sanh was a combat base tucked just under the demilitarized zone (DMZ) in the foothills of the Annamite Range. Here, a road crossed from South Vietnam into Laos, used for Indochinese commerce in peacetime but an important position in war. For the allies, Khe Sanh represented the northwest anchor of their DMZ fighting positions. It was also the base from which, if there were ever an offensive into Laos to sever the Ho Chi Minh Trail, such an operation would inevitably be launched. Khe Sanh was a starting point for special operations aimed at the trail, and a lookout position against enemy maneuvers. It had started out as a South Vietnamese army (ARVN, or Army of the Republic of Vietnam) post and was eventually succeeded by a U.S. Special Forces camp, from whose airfield flew the first experimental forward-air-controller aircraft that directed strikes against the enemy logistic network in Laos, the DMZ and the panhandle of North Vietnam.

Khe Sanh was a burr under Hanoi’s saddle. Its early southbound infiltration groups had had to pass the ARVN post. And later, when the trail became an organized network, the North Vietnamese faced a stream of Special Forces forays codenamed “Shining Brass,” which used Khe Sanh to insert patrols to harass Hanoi’s supply lines. The North Vietnamese made repeated efforts to neutralize it. In January 1966, they shelled the Special Forces camp, surprising the garrison at evening formation. The allies, refining their disposition, moved the Special Forces to Lang Vei, closer to the Laotian border, and created a Marine Corps combat base. In April 1967, Marines sweeping the hills to the north encountered dug-in North Vietnamese troops and fought a pitched battle to eject them. Then, in early May, the enemy launched a carefully prepared assault on Lang Vei.

The “Hill Fights” and the first Lang Vei battle marked a new phase in the history of the post. The U.S. commander in Vietnam, Gen. William C. Westmoreland, who sought to bar the borders to the enemy, emphasized the war in the north.

Washington agreed and ordained a defense along the DMZ that became known as the McNamara Line. As the westernmost anchor of that line, Khe Sanh needed to be defended in force. Local commanders recognized that the hills overlooked their combat base – the Hill Fights resulted from a move to emplace Marine strongpoints on key outcroppings. Pacification efforts led to the placement of a Marine Combined Action Platoon at Khe Sanh village. During the last half of 1967, Khe Sanh grew into a major defensive complex that included the combat base, four hilltop strongpoints, a mountaintop observation post, the village itself and Lang Vei.

Hanoi made its own calculations. About the same time the Americans began expanding their dispositions, North Vietnam decided on the Tet Offensive, and part of the plan included a major attack on Khe Sanh. It remains unclear whether Hanoi intended Khe Sanh as a diversion to pave the way for Tet, or if the countrywide attacks were supposed to preoccupy the allies while Khe Sanh was overrun. Hanoi mounted other diversions prior to Tet – notably at Loc Ninh in the south and Dak To in the Central Highlands – and a Khe Sanh threat was the kind of thing the Americans would understand and respond to, so the evidence suggests that it started out as part of North Vietnam’s deception plan. But it was built upon a real assault. Two full divisions of North Vietnamese troops and parts of another, units associated with a nearby trail way station, heavy artillery units and tanks were all brought to the Khe Sanh sector. U.S. communications intelligence and aerial reconnaissance detected some of these movements, and Westmoreland reinforced Khe Sanh accordingly. The last units arrived a few days after the battle began, making a total of four U.S. Marine Corps battalions, an ARVN Ranger battalion, a Special Forces contingent, the troops at Khe Sanh village, and the Special Forces and indigenous troops at Lang Vei – about 7,400 men in all – facing an estimated 27,000 North Vietnamese.

The Khe Sanh siege opened Jan. 21, 1968, more than a week ahead of Tet. A major bombardment of the combat base, followed by an assault on Khe Sanh village and the strongpoint atop Hill 861, started the action. The bombardment ignited shells stacked in munitions dumps and destroyed a good deal of the Marines’ artillery ammunition. The village was lost, but the Marines held onto Hill 861. Then Khe Sanh fell silent except for the constant North Vietnamese bombardments. The Marines set up two new strongpoints. Westmoreland feared the initial actions were just the prelude to a full-scale assault. The final days before Tet had him preoccupied with Khe Sanh, funneling the last two battalions into the base and setting up a massive air support effort – Operation Niagara – to obliterate the enemy. The Americans used everything, right up to B-52s striking dangerously close to U.S. positions. The crowning touch was a sophisticated electronic sensor system to warn of the approaching enemy.

When Tet came, Khe Sanh remained quiet. The Marines refused to speak of the battle as a siege. Their commander, Col. David Lownds, privately studied accounts of the eerily similar battle at Dien Bien Phu while telling others in public, “Wars are won by one guy beating the other guy.” Lownds’ other Marine unit, the 1st Battalion, 9th Marines, had fought hard battles at Con Thien below the DMZ, where they had gained the sobriquet “The Walking Dead.” Also among his force were the ARVN 37th Ranger Battalion, and the Studies and Observation Group’s Forward Operating Base 3.

“Quiet” at Khe Sanh meant the absence of North Vietnamese assaults, but there were constant patrol actions, sudden sightings of the enemy and incessant shelling. A few days ahead of Tet, the Vietnamese began using heavy artillery – 122 mm, 152 mm and 130 mm guns – for the first time in the war. Defenders became familiar with the pattern of the bombardments and adopted the “Khe Sanh shuffle,” a cover-run-duck technique to minimize dangers from the enemy artillery, rockets and mortars. Every day the defenders counted, and Lownds reported, the number of shells that hit allied positions. The record was 1,307 shells on Feb. 23. Through the entire month of March, the North Vietnamese sustained their bombardment at an average of 150 shells per day. Soon enough, bunker fatigue complemented the shuffle. North Vietnamese histories record that 243 fire missions were conducted during the high siege. They note expenditure of 9,423 rounds before the allies began their relief effort. Slightly more than 700 rockets were fired at the Marines.

Back in Washington, Gen. Maxwell Taylor, who advised President Lyndon Johnson, tried to reassure his colleagues by arguing that “no one should expect an outpost to be a Verdun.” Just two days later, the quiet at Khe Sanh ended. Vietnamese sources record that on Feb. 2, while Washington agonized over Khe Sanh, North Vietnamese chief of staff Gen. Van Tien Dung telephoned front commander Gen. Tran Van Hai, demanding to know what obstacles prevented his troops from attacking more forcefully to draw in the Americans. The complaint spurred Hai to action. On Feb. 5, the North Vietnamese struck with a four-hour bombardment coupled with an assault on Hill 861A. Then came an attack on Hill 881 South. On Feb. 7, the Vietnamese overran the Lang Vei Special Forces camp using tanks – another first. And the next day, at Hill 64 – better known as the “Rock Quarry” – the enemy lashed out at “The Walking Dead.” This first week of February marked the high point of the campaign.

The Rock Quarry fight marked the last major assault of the campaign. Much had changed. Entrenching now marked the high siege phase. On at least two occasions, the U.S. electronic sensors seemed to indicate the enemy assembling for a big attack, both times broken up by intensive airstrikes and artillery shoots. Over the length of the siege, the Navy, Air Force and Marine fighter-bombers in Operation Niagara, plus the Air Force B-52s, delivered more than 98,700 tons of munitions on targets around Khe Sanh. The last significant attack, aimed at the combat base itself, went against the ARVN Rangers on Feb. 21. Before the end of the month, the North Vietnamese general staff instructed Hai to send his 325C Division to the Central Highlands. One regiment stayed behind until mid-March to stiffen the siege forces. Thus the People’s Army at Khe Sanh actually had its 304th Division (less one battalion) reinforced by a regiment of 325C, for a total of 11 rifle battalions through most of the siege. At the beginning of April, Westmoreland launched a major offensive – Operation Pegasus – designed to reopen land access to Khe Sanh along the Route 9 highway. The relief force linked up with Lownds’ defenders on April 9, ending Khe Sanh’s misery.

Remarkable in many ways, the siege of Khe Sanh must rank as one of the most important battles of the war in Vietnam. It is also among the most difficult to assess. Because of its timing in relation to that of the Tet Offensive and Hanoi’s clear interest in a deception plan to cover the latter, and because the North Vietnamese kept Khe Sanh under siege without consummating their assault, some of the standard criteria for judging outcomes remain imponderable. Westmoreland certainly considered Khe Sanh a victory. Many Marines do, too. By some measures, it certainly is. The allies kept control of the battlefield, were never overcome and inflicted many casualties on the enemy: Lownds’ troops counted 1,602 enemy bodies on the battlefield and estimated more than 10,000 enemy wounded. Military and intelligence analyses for President Johnson estimated North Vietnamese losses at between 14,600 and 28,900. Careful compilation of Marine Corps and other casualty figures for the campaign indicate overall allied losses of 730 dead, 2,642 wounded, and seven missing. Judging by losses and control, Khe Sanh was an allied victory. A large North Vietnamese expeditionary force absorbed tremendous losses while accomplishing little beyond the capture of the Lang Vei camp and Khe Sanh village.

There were other successes as well. Khe Sanh marked the first application of the “electronic battlefield,” a warfare environment that increased in sophistication until it became predominant during the 1991 Gulf War. Khe Sanh is the first known instance in warfare in which an adversary’s attack, detected only electronically, appears to have been disrupted without ever reaching contact. Techniques for aerial resupply pioneered at Khe Sanh became staples in U.S. practice. The air-support management system developed to conduct Operation Niagara set a new standard for Southeast Asian operations.

And there were setbacks. The South Vietnamese government never attempted to regenerate the civil administration it had had in the region before the siege, abandoning the countryside to the North Vietnamese. Meanwhile, Hanoi’s troop deployment leveled off after the siege at roughly double the strength that had been in the sector in 1967, when the security situation had already been considered serious. And the North Vietnamese demonstrated beyond a doubt that they had a hard shell to defend the Ho Chi Minh Trail, effectively canceling Westmoreland’s dream of invading Laos to cut it. 

Then there is the matter of Hanoi’s intentions. If its purpose was to shield the preparations for Tet, then the outcome proved a signal success, because Westmoreland remained mesmerized by the prospect of a pitched battle along the Vietnamese frontier. Hanoi’s assignment to Khe Sanh of a smaller contingent than necessary to pursue a true decisive battle, and its diversion to other fronts of seven of the 18 rifle battalions in even that smaller force, all indicate that a repeat of Dien Bien Phu was not its aim. On the other hand, Hanoi’s orders in February to eliminate large U.S. units does show purpose beyond merely masking the position. Vietnamese accounts suggest that by posing a significant threat, North Vietnam hoped to divert the U.S. command, while such destruction of U.S. forces as could be accomplished would contribute even more to the impact of the Tet Offensive. In the end, there was more than one victory at Khe Sanh – and more than one defeat.

John Prados and Ray W. Stubbe are authors of “Valley of Decision: The Siege of Khe Sanh.” Stubbe lives in retirement in Milwaukee, where he is active in 3rd Marine Division and Khe Sanh veterans groups. Prados’ current book is “The Family Jewels: The CIA, Secrecy, and Presidential Power (University of Texas Press).