NVA Bunkers at Khe Sanh - Introduction

This series of articles on NVA bunkers is based upon an analysis of enemy positions at Khe Sanh that was carried out by the 3rd Marine Division. The purpose of their study was to produce an evaluation of the effectiveness of various weapons systems employed against the enemies fortifications. Whilst the tactics of the NVA at Khe Sanh were somewhat different from those previously encountered by US forces, his defensive concepts relating to the use of trenches, tunnels, and fortifications were similar to those used previously. All map references are to US military maps of the Khe Sanh area.

In the Marine study, all of the position types were examined from an engineering aspect, and then analyzed in relation to the supporting arms employed against them. Where possible, their tactical location and relationship to other nearby positions was also studied in order to determine their purpose, interrelationship, and ability to withstand assault by fire. No attempt was made however to determine or define the overall scheme of operations of the NVA forces at Khe Sanh. It was accepted that although these positions represented only a small fraction of the battlefield, they were nonetheless considered as being representative of NVA construction and placement.

The study concluded that friendly weapons systems proved to be highly effective against the enemy fortifications and this was evidenced by the enemy having abandoned the battlefield, leaving behind mounds of supplies and piles of unburied dead, a rare occurrence on the part of the NVA.

Individual Living & Fighting Holes

Individual fighting holes were designed to afford the occupants both protection from fire and shelter from the elements. The holes were first dug, and then lined with locally procured materials. Cover was placed on the top and served as a means of protection and camouflage. The typical hole measured 3x6x4 feet (Fig. 1) and was both carefully and deliberately camouflaged. Estimated occupancy was from one to three days. No supporting arms were employed against this type of position.

The holes were located approximately 10 feet from a heavily used trail on the south-eastern slope of Hill 678 (XD 851328) where the foliage consisted of dense bamboo thickets, banana trees and miscellaneous broad leaf trees which formed a canopy between 15 and 40 feet above the ground.

The positions had served as a temporary resting place for small groups of people moving over long distances, or were used by the point or advance guard of a large unit. The absence of spoil, waste and other human detritus suggested the former, although a large complex was subsequently found several hundred meters away.

Unit Bivouac Sites & Hasty Positions

Hasty positions were generally constructed for rapid protection and short-term occupancy. They varied in size from single individual sleeping holes to company and battalion sized complexes consisting of multiple fighting holes and storage areas. The notable absence of trenches tended to indicate that these areas were not exploited for prolonged defense. This was further borne out by the fact that no individual camouflage precautions were present and the spoil had been piled on the edges of the holes to form a protective berm.

Holes had been scooped out and then lined with leaves and matting. Again, no supporting arms were employed against this position. Figure 2 shows the general design and layout of a large bivouac site located on the east side of a hill 200 meters above the Khe Cham River, under a solid tree canopy at XD 855322. The hill mass ran in a north-south direction at an altitude of 500 meters. The area closely followed the pattern of most living areas, i.e., on reverse slopes between the topographic crest and the nearest water source.

In areas where heavy canopy existed, no concealment measures were taken however, heavy security was invariably placed on the perimeter of these areas. It is worth noting that subsequent observation flights over the area were unable to locate the position under the dense canopy.

All indications pointed to this area as being a stop-over point for a company sized unit. There were over 100 various-sized sleeping and fighting holes in the area and each group of sleeping holes was protected by an outer perimeter of fighting holes. Within the inner perimeter, sleeping holes were scattered in a random fashion, generally along either side of the trail.

Antiaircraft Positions

One of the most readily identifiable NVA fortifications was the single or multiple antiaircraft site. Single positions were used in conjunction with living areas, trench complexes, supply routes, and were located within each complex, or directly adjacent to it. Multiple positions in either a triangular or linear formation were employed on hilltops and high terrain to provide security to base areas, storage and logistic points. These positions were in single groups or mutually supporting complexes. Each position was capable of independent action. Figure 3 and Figure 5 illustrate the positions located at XD 847317 and XD 853309. Subsequent searches of these positions recovered spent 12.7mm brass casings.

The positions were located on a ridge-line which extended from XD 844316 to XD 850305 in a southerly direction. Each position afforded an excellent view of the surrounding terrain. No attempts had been made to camouflage either position, although the command and control bunker in figure 5 had been camouflaged prior to a fire which had burned across the position. Trenches connected each gun position within either complex but the two main positions were connected only by a trail and communications wire. Both positions had short escape trenches leading to a concealed area 60 feet away. No evidence of a living or storage area was seen from either ridge. However, subsequent photography revealed two large bunker complexes at XD 844315 and XD 854312.

The holes were well constructed, especially the ammunition storage and protective bunkers associated with each position. These bunkers afforded adequate protection from anything but a direct hit. The bunkers had 3 feet of mounded overhead cover consisting of 3-inch logs, rock, and earth fill. One or two holes in each complex contained center pedestals 8 inches high and 2 feet in diameter.

The linear position measured 100 feet long. A 4x6x4 foot command/control bunker was located 20 feet to the rear. Connecting trenches had one 3x6x3 foot protective bunker cut into the side. Communications wire was scattered throughout the area.

Of the sites inspected and photographed, the triangular position at XD 847317 had been attacked with the greatest accuracy. Figure 3 shows the single 500/750 lb. bomb crater placed directly in the center of the three positions. There was no visible damage to any of the positions, or to the living/storage bunkers cut into the side of the gun pit. The accuracy of the bomb placement and comparison of the crater to others within 100 meters of the position indicated that the position had been visually acquired and then attacked.

NVA Hilltop Defensive Positions

On Hill 663 (XD 828321) Marines encountered a defensive positions that consisted of forty to fifty 'tepee' style living and fighting bunkers arranged in mutually supporting concentric circles just below the topographic crest of the hill.

The hill was partially wooded with large patches of elephant grass and low shrubs. The gradient on the western slope averaged 45 degrees. The hill sloped to a small plateau located 150 meters to the east on a small finger. The soil was of laterite composition with no rock present. Excellent observation and fields of fire were available in all directions. The NVA had used the hill as a defended observation post and strong point protecting the southern approach to Khe Sanh. The position presented a defense in depth from any approach. No booby trap devices were encountered by the troops occupying the hill.

The 'tepee' style bunker consisted of an A-Frame and the overhead cover arrangement was unique among the various bunkers seen on the battlefield. There were numerous reports confirming its widespread use throughout the Khe Sanh area. The bunker was constructed in the standard 4x6x4 foot fighting hole, giving it an underground 'pup tent' appearance (Fig. 7). This type of construction offered the best protection, exposed very little to the observer, and was one of the strongest construction styles devised. The 4x6x4 foot trench provided the basis for the bunker with each side entrance faced at right angles to the direction in which the bunker was oriented.

The 'tepee' bunker and its unique overhead demonstrated a basic knowledge of engineering by the NVA soldier. The overhead logs measured 5-6 feet long and were embedded six to ten inches in the floor of the bunker at a 45 degree angle, forming an equilateral triangle. At the apex, the logs ware lashed to a 12-inch center support beam. Where the 12-inch logs ware not available, several smaller logs had been laced together. Entrances sloped from ground level to the bunker floor at a 45 degree angle, leaving a small hole that could be seen only from overhead. Each bunker contained a 6 inch air vent in the wall furthest from the entrance. There were no apertures found in these bunkers. Many of the bunkers were blown by the US forces with internally placed charges. This method destroyed the overhead protection but did not break the timbers or logs. In a few hours the bunker could be reconstructed.

The hill was attacked with general purpose (GP) bombs, rockets, napalm and artillery. The napalm had burned away much of the underbrush on the eastern slope exposing several bunkers. Of those exposed all were charred on the inside, but only the grass matting had burned and the structure had not been weakened. Numerous 250 and 500 lb bomb craters were in close proximity to the positions, but no bunkers were found that had received a direct hit.

Soil and bunker composition required attack utilizing delay fuzing; however, the artillery delay penetrated the soil six to eight feet before detonating and was of limited use against the bunkers. Surprisingly, the employment of quick fuzed artillery would have been more effective in lieu of a shorter delay, mechanism.

Eleven bodies ware found in the complex above ground. Most were uncovered in their bunkers as the US troops dug in for the evening. The fact that they had stayed on the hill in the face of heavy aerial and artillery bombardment attested to the hills significance. Although the bodies had been on the hill from 10-15 days, many were observed to have large fragment holes and similar disfigurations. One skull had a 2x5 inch hole, and several helmets with fragment holes were lying about the hill. The dead appeared to have been caught above ground by the bombs and artillery.

The foremost question that faced the supporting arms planner in attacking a complex of unknown size and composition normally involved fuzing requirements. Although the tendency to employ delay fuzing was strong, the planner had to consider that soil composition may, on occasion, render the delay fuze useless. The probability of a direct hit was small, and the delay often penetrated through the bunker, exploding underground. In some cases, high angle surprise fire employing VT and quick fuzing had more effect than a reliance on delay fuzing.