The Battle for Khe Sanh

by Moyers S. Shore

Marines at the combat base run for cover when warning of enemy rocket or artillery attack is sounded. (USMC Photo A190245)

Machine gunners lie on top of trench cover while they search for enemy movement. (USMC Photo A190929)

The regimental commander placed a minimum requirement on his subordinates of providing overhead cover for the troops that would stop, at least, an 82mm mortar round. The FSCC determined that one strip of runway matting and two or three layers of sandbags would fill the requirement. The average bunker usually started as an 8x8 foot dugout with one 6x6 inch timber inserted in each corner and the center for support. The overhead consisted of planks, a strip of runway matting, sandbags, loose dirt, and more sandbags. Some enterprising Marines piled on more loose dirt, then took discarded 105mm casings and drove them into the top of the bunker like nails. These casings often caused pre-detonation of the heavier-caliber rounds. The combat engineers attached to the 26th Marines could build one of these bunkers in three or four days; the average infantrymen took longer. Overhead cover for the trenchlines consisted of a strip of matting placed across the top of the trench at intervals and reinforced with sandbags. The defenders could stand up in the trench during periods of inactivity and duck under the matting when enemy rounds started to fall.[(81)]

The Marines were also faced with another question concerning their defenses: "How large an artillery round could you defend against and still remain within the realm of practicality?" Since the 26th Marines was supplied solely by air, building material was a prime consideration. Matting and sandbags were easy enough to come by but lumber was at a premium. Fortifications which could withstand a hit from an 82mm mortar were a must because the North Vietnamese had an ample supply of these weapons but the base was also being pounded, to a lesser degree, by heavier-caliber guns. With the material available to the 26th Marines, it was virtually impossible to construct a shelter that was thick enough or deep enough to stop the heavy stuff.[(82)]

This fact was borne out when Colonel Lownds decided to build a new regimental CP bunker. The engineers supplied the specifications for an overhead that would withstand a 122mm rocket; to be on the safe side, the colonel doubled the thickness of the roof. The day before the CP was to be occupied, a 152mm round landed squarely on top of the bunker and penetrated both layers.[(83)]

The massing of enemy artillery made the hill outposts that much more important. Had they been able to knock the Marines from those summits, the North Vietnamese would have been able to fire right down the throats of the base defenders and make their position untenable. As it was, the companies on Hills 881S, 861, 861A, and 558 not only denied the enemy an unobstructed firing platform from which to pound the installation, they also served as the eyes for the rest of the regiment in the valley which was relatively blind to enemy movement. For observation purposes, Hill 881S was the most strategically located and a discussion of the enemy's heavy weaponry will point out why.

While the 60mm and 82mm mortars were scattered around in proximity of the combat base (roughly within a 2,000-3,000 meter radius), the NVA rocket sites and artillery pieces were located well to the west, southwest, and northwest, outside of friendly counterbattery range. One particularly awesome and effective weapon was the Soviet-built 122mm rocket, the ballistic characteristics of which had a lot to do with the way the North Vietnamese employed it. When fired, the projectile was fairly accurate in deflection but, because it was powered by a propellant, the biggest margin of error was in range. Consequently, the North Vietnamese preferred to position their launching sites so the gunners could track along the long axis of a given target; thus, longs and shorts would land "in the ballpark." The KSCB hugged the airstrip and was roughly in the shape of a rectangle with the long axis running east and west. This made the optimum firing positions for the 122mm rocket either to the east or west of the base on line with the runway. There was really only one logical choice because the eastern site would have placed the rockets within range of the Americans' 175s and extended the enemy's supply lines from Laos. To the west, Hills 881S or 861 would have been ideal locations because in clear weather those vantage points provided an excellent view of Khe Sanh and were almost directly on line with the airstrip. Unfortunately for the NVA, the Marines had squatters' rights on those pieces of real estate and were rather hostile to claim jumpers. As an alternative, the North Vietnamese decided on 881N but this choice had one drawback since the line of sight between that northern peak and the combat base was masked by the top of Hill 861. Nevertheless, the enemy emplaced hundreds of launching sites along its slopes and throughout the siege approximately 5,000 122mm rockets rained on Khe Sanh from 881N.[(84)]

Because of their greater range, the enemy's 130mm and 152mm artillery batteries were located even further to the west. These guns were cleverly concealed in two main firing positions. One was on Co Roc Mountain which was southwest of where Route 9 crossed the Laotian border; the other area was 305, so called because it was on a bearing of 305 degrees (west-northwest) from Hill 881S at a range of about 10,000 meters. While the heavy caliber artillery rounds which periodically ripped into the base were usually referred to as originating from Co Roc, 305 was the source of about 60-70 percent of this fire, probably because it was adjacent to a main supply artery. Both sites were vulnerable only to air attack and were extremely difficult to pinpoint because of the enemy's masterful job of camouflage, his cautious employment, and the extreme distance from friendly observation posts. The NVA gunners fired only a few rounds every hour so that continuous muzzle flashes did not betray their positions and, after each round, quickly scurried out to cover the guns with protective nets and screens. Some pieces, mounted on tracks, were wheeled out of caves in Co Roc Mountain, fired, and returned immediately. Though never used in as great a quantity as the rockets and mortars, these shells wreaked havoc at Khe Sanh because there was very little that they could not penetrate; even duds went about four feet into the ground.[(85)]