Enemy Bunker Systems
The Viet Cong and North Vietnamese Army units tended to locate their sanctuaries in dense jungle forests and mountainous cave systems. Whilst 5RAR confronted both kinds in most parts of Phuoc Tuy and the surrounding provinces, probably the greatest concentration of bunker systems encountered was in Bien Hoa Province (where we fought HQ MR7) and into the Hat Dich Secret Zone which stretched across the border into north-west Phuoc Tuy Province. Of the mountain defensive positions we confronted, some of the most formidable opposition was found in the May Tao Mountains and the Nui Thi Vai complex.
Enemy defensive positions were always well-camouflaged, sited in all-round defence, mutually-supporting and with bunkers and weapon pits in depth. Quite often a system formed a star shape whilst others utilised the shape of the terrain. A system could vary from just a few to 200 bunkers, but the average was between 20 and 40, covering an area of about 150 x 200 yards. Some or all bunkers in a system were connected by crawl trenches and, in some cases, tunnels.
The average bunker dimensions were 10 x 6 feet, about 5 feet deep and with 3 to 5 feet of overhead protection of logs, dirt and foliage. This provided camouflage from both aerial and ground observation and protection to withstand aerial and artillery bombardment other than a direct hit from a B52 strike. The average silhouette above ground was about 2 feet. There was an entrance and exit hole (from which most fighting was done or from the reverse side of the roof which acted as a parapet). There were frequently weapon pits outside the bunkers, sited to provide depth and mutual support.
The camouflage was such that usually bunkers could not be seen at greater than 10 yards. The average distance for an initial contact, often when the enemy fired on our searching troops, was at this 10 yard point but some contacts were initiated at 25 yards or as close as 6 feet. The enemy used well-concealed fire lanes where the undergrowth was slightly trimmed from the ground to about a foot high. From the standing position this could not be observed.
To avoid casualties from that initial contact it became imperative to recognise the signs of a bunker complex nearby. The usual "sign" was the thickness of the forest or bamboo, some timber cutting (with the stumps usually camouflaged with mud and twigs), a track pattern, markings on the tracks (such as wooden arrows and crossed sticks), leaves stripped off twigs, cooking smells, the ethnic body smell, latrine smells, camouflaged panji pits and the close proximity of a stream or actual water points.
The next main problem was to ascertain the size and layout of a system. Reconnaissance patrols were used for this. Methods of attacking a bunker system included:
- the immediate assault. This was the shock action of following up an initial contact with a quick aggressive attack on a wide front. This method was usually confined to platoon level and was risky against a determined enemy. There was no preparatory bombardment.
- withdrawal and subsequent deliberate assault. This was preceded by artillery and aerial strikes, ideally with blocking ambushes in depth. The assaulting troops were then usually supported by helicopter gunships firing into the bunker system. The leading sections would move in bounds using fire and movement. It was of major assistance to have the support of tanks and/or APCs but these were rarely available because of the remoteness of the areas. These tracked vehicles were particularly effective in destroying the bunkers by driving over them and swivelling their tracks so as to collapse the structure.
- surrounding the bunker system with blocking forces and waiting for the enemy to leave his defences and walk into our ambushes. Sometimes it would be completely silent, while at other times the enemy might be forced out by artillery or aerial strikes.
There were many variations of the above.
The sappers of the engineer splinter teams were attached to rifle companies and had the unenviable task searching, de-mining and destroying captured enemy bunkers. These "Tunnel Rats" from 1st Field Squadron did a magnificent, courageous job and saved the lives of many members of 5RAR.
© David Wilkins
Adjutant & OC C Company
2nd Tour