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The Tunnels of Cu Chi

The tunnels in Cu Chi were originally dug as hiding places for the Viet Minh, the nationalist guerillas who fought the colonial power, France, in the 1940s and 1950s. As with their successors the Viet Cong, communists dominated the independence movement.

The tunnels were dug for communication from one hamlet to another so that the Viet Minh could evade French army sweeps or spotter planes. Major Nguyen Quot, a short wiry cadaverous officer, who spent the best part of ten years living in Cu Chi's tunnels, explains their origin. "The tunnels were started in areas temporarily occupied by the enemy. The revolutionary forces were small. It would have been impossible for our forces to survive if we had fought in the open. We had to be in a position where we could choose the time, the place, and the target of attack. By 1948 we had already dug a tunnel system: Each family, each hamlet, had a tunnel communicating it with others."

In December 1958, several hundred suspected communists or dissidents were poisoned to death with dosed bread at a prison camp at Phu Loi, a few miles to the east of Cu Chi across the Saigon River. This massacre generated a new mood of militancy; the famous Viet Cong Phu Loi battalion would be named after the event. Under law 10/59 (the month of its enactment) President Diem specifically outlawed former Viet Minh fighters. Resistance to Diem increased. At the village of Phuoc Hiep, just north of Cu Chi town, is a memorial to marchers in a demonstration in 1961, gunned down by members of the Army of the Republic of Vietnam (normally written ARVN and pronounced "Arvin" by the Americans. They had established a parachute training school in the nearby Cu Chi village of Trung Lap.

At long last, in 1960, the Communists lifted the ban on armed resistance; the National Liberation Front (NLF) a Communist dominated coalition of anti-government groups, was formed to supervise the resumption of guerrilla war in the south. Co-ordinated armed attacks began on army and police posts, and for the first time the essential weakness of the Diem regime was exposed. Army posts were either easily overrun or sufficiently intimidated by demonstrators or persuaded by the threats and blandishments of villagers so that all the weapons were surrendered. To the exasperation of their American advisers, the ARVN units deliberately avoided enemy contact and the consequent casualties. One by one the villages of Cu Chi and adjoining districts disarmed local ARVN detachments and effectively cut themselves off from government control. The arms acquired by this means were the first and only weapons many nascent Viet Cong units had; enterprising villagers set about making copies, founding the huge cottage ordnance industry in the tunnels that would last until the late sixties, when newer guns came south from Hanoi.

With the resumption of guerilla warfare the old redoubts of the Viet Minh had to be re-activated. The French had used aircraft to spot and bomb the Vietnamese fighters; Diem's army was increasingly transported by American helicopters. In villages all over Cu Chi, Tay Ninh, the Iron Triangle, and wherever possible, old tunnel networks were repaired, and a great program of tunnel digging began. "When we got orders to set up a secure basket here," related one Cu Chi survivor of that period, ex guerilla Ba Huyet, "the first thing we did was to start digging 30 kilometres of underground tunnels. It was in 1960. Not only was this one of our closest outposts to Saigon, but it was our advanced command post throughout the war. The Americans were sure something was going on here, but they were not sure what."

Tunnel veteran major Nguyen Quot estimated that 48 kilometres of tunnel excavated during the war against the French had grown to 200 kilometres by the time the American army had arrived in 1965. After 1961, hitherto piecemeal local digging was connected up to form an integrated network. The Americans would nick name it the little IRT, after part of the New York City subway system.
Operation Crimp was a massive American attack set to strike at the very heart of the Viet Cong machine in South Vietnam, at the notorious Ho Bo Woods just west of the famed iron triangle itself. This no-nonsense offensive was planned to destroy the long time communist redoubt by finding and eliminating the headquarters of the entire Viet Cong military region 4.

When this operation started the Viet Cong would fire on the Americans and then disappear, and this was to confuse the Americans no-end. They started to find the tunnels of course but there was nothing in the training manual about tunnel warfare. Neither the Americans nor the Australians had any experience dealing with what to them was a new phenomenon. But they were relatively unconcerned; the famous OJT principle (on the job training) would somehow see them through. But in January 1966, muddling through, adapting, applying combat training would not be enough to wipe out the communist presence in the "liberated zones" of Cu Chi District.

The tunnel rat was new job, and it was to stand proud and isolated within the ranks of the best equipped army in the world. These tunnel rats soon discovered that the standard infantryman's equipment was not for him. To the contrary, he discovered that the less he took into the sweaty darkness, the better the chances of survival. He was soon to realise that neither firepower, high technology, or personal armour would ever give him an advantage over his invisible enemy.

The bayonet, the pistol and the flashlight were the basic tools for survival inside the tunnels of Cu Chi or indeed anywhere an engineer was required to descend to the depths of the earth. Only having two hands, the tunnel rat was restricted to a torch in one hand and the bayonet (as a prodder for unseen traps etc) in the other. Indeed, the very reverse of high tech weapons development took place within the tiny ranks of the tunnel rats.


Australians first contacted the VC in the tunnels when working with the 173rd Airborne. One of the tunnels first victims was an Australian Engineer, Corporal Bob Bowtell of 3 Field Troop, Royal Australian Engineers. The troop was part if 1 battalion group, Royal Australian Regiment, bought in to act as a blocking force on the northern perimeter of Operation Crimp. An area covered with light scrub, rubber plantations and secondary growth. The Aussies, with their traditional bush hats and British military background, made a distinct and colorful background to the GI's. They were all volunteers and all were keen to find the action.

3 Field Troop was led by a large, beefy, officer, Captain Alex (Sandy) McGregor. He was known in military jargon as a hands on type, an officer who truly led his men and would ask from them nothing that he had not done or would not do himself. He was a front row rugby forward and built like an ox. He had already spent two years with an engineer construction squadron in Papua New Guinea, a place not generally regarded as being particularly homely or comfortable for a white man. In Vietnam he was one soldier who dealt with the prevalent foot rot problem in a robust way: he discarded his socks and suffered the agonies of blisters for several days, but then as calluses formed his feet slowly developed a covering that was actually tougher than the combat boots he wore.

Under his command McGregor had almost 70 Engineers. Divided into 4 Sections with a HQ section. They included Cooks, Mechanics, Storemen,Carpenters, Plumbers, Plant Operators, Drivers, and the life blood of any Field Troop or Squadron, the Combat Engineers (Field Engineers). They included Sapper Dennis Ayoub, his radio man, and sappers Les Colmer and Barry Harford. Colmer was McGregor's batman, but unlike the "butler" batman of the British system, he followed his boss, often into enemy fire. Sapper Harford was Colmers friend; both had joined the army from Broken Hill, the large mining town in New South Wales.

On the first day of Crimp the troop found action without difficulty. Home made grenades were spotted rigged as anti-personnel mines, with trip wires strung from the trees from ankle height to head height. On the second day they even ran across two mortar bombs activated by a grenade connected to an ankle high trip wire. Later that day they found an area laced with punji stakes (razor sharp bamboo spikes) set in concrete in the ground. A sapper of B Company demolition team trod on one and it went straight through his foot. By day three the Australian Infantrymen were beginning to take serious casualties.

Captain McGregor recalled that not only were the scouts of one leading infantry company killed, but when the stretcher bearers were called to evacuate the wounded, they were killed too. In one action alone, four Aussies died. McGregor and his engineer troop were called in when it became obvious that although the hot area had been surrounded, no Viet Cong had been sighted or killed. There was only one conclusion. They had, in the Captains words, "gone down." As the Australian ring of steel closed on the area, they found the tunnels.

Over the next four days, working with the Americans, the Australians slowly uncovered at least 3/4 of a mile of communication tunnels, bunkers and underground chambers. McGregors men had been in the country for four months, this was their 5th operation, and they were neither baffled by or unduly apprehensive about the tunnels. They went down and explored. But there were mistakes.

They used a specially adapted commercial air blower called the 'mighty mite' to blow smoke down the tunnels, then watch carefully to see where the smoke came out of the ground so they could begin a rough plot of where the tunnels spread. But the smoke stayed underground, and when the first Australian tunnel-ferrets (as they were called then) went below. They quickly became unconscious because of lack of oxygen. This is how Corporal Bowtell died, in a tunnel war that was about to break out in earnest.
While exploring underground, Bowtell, a typically tall, lean Australian, unwisely tried to wriggle through a tiny trapdoor connecting one tunnel level with another. It measured 16 inches by 11 inches, dimensions that would hardly have allowed a lithe Viet Cong guerilla through, let alone a large framed westerner. Bowtell got stuck and within seconds realised that lingering smoke from the 'Might Mite' had expelled most of the oxygen in the tunnel. He shouted for help.

Private Jim Daly (1 RAR) volunteered to try to rescue Bob Bowtell, but by the time he got to the trapdoor, Bowtell was already unconscious. Futile attempts began above ground to sink an air shaft to the trapped sapper. Daly himself was almost asphyxiated by the lingering fumes, but he had to try to cut Bowtell free with his knife by enlarging the tiny trapdoor frame in which the corporal's limp body was trapped. Four times he tried but he failed to drag the corporal out, and finally, on the verge of collapse himself, was ordered to stop. Pte Jim Daly 1 RAR was awarded an MID for his "sense of purpose, coolness in action, and disregard for his own safety, which was an inspiration to all those who fought with him."

After Bowtells death, McGregor made sure that no similar accidental deaths were ever to afflict the Australians. Meanwhile searching and destroying these incredible underground tunnels had to continue. Les Colmer and Barry Harford, the men from Broken Hill, volunteered to work with demolition explosives in the tunnels. Using his communication skills, Denis Ayoub rigged up a proficient underground telephone system. He found ammunition caches stored in small chambers, small booby trapped Parker 57 pens, and even underground flag making shops, complete with sewing machines. Large rice caches were also found, every one of them booby trapped- not just around the cache - but even inside the bags themselves.

McGregor made copious notes of what his men found. Only his bulk prevented him from leading his men through the never ending network of tunnels. It was McGregor who realised the value to the Viet Cong of American combat detritus, after Denis Ayoub found a small tunnel workshop in which hand grenades were made. The inner case was made from a small discarded tomato juice tin and the outer case from an old beer can. The fragmentation pieces were blue metal road gravel, and the firing mechanism was from old French or American grenades.

"Because of what we found in the tunnels," recalled McGregor, "we ordered this policy of burn, bash, and bury. We had 24 hour ration packs with little tins in them. You never ever leave your tins around so that they could be found, you never left anything the enemy could use. Your spoon, they would use that for making weapons. We left nothing, absolutely nothing."

This was a discipline that the GI's could have emulated more enthusiastically. As the war became even harder on the Viet Cong, they used the waste so generously left around by the Americans more and more, and in some areas they became dependant on it.

Tensions between the specialist engineers and the infantry began to show early in Operation Crimp. In an official Australian after action report, the following laconic comments were recorded:
In some cases, having secured tunnel entrances, infantry moved on to secure other locations, leaving sappers underground with no immediate close in protection. This does not foster confidence. One instance occurred where sappers were searching a tunnel under a house and the infantry commenced to burn the house. Sappers lose confidence under those circumstances.

There was some discord between the lanky Australians and their American comrades too. Sapper (now Major) Denis Ayoub said quite bluntly: "The Americans taught us nothing about tunnel fighting in an hour that we hadn't already tried ourselves. Our determination to clear tunnels seemed to them to be nothing short of madness. They were quite surprised when we said we were going to send guys down with torch and a pistol and a length of string."

While the Australians began to develop the earliest techniques for exploring and destroying some short tunnel systems, they had no real plan for dealing with the heart stopping business of actually running into a Viet Cong guerilla inside a tunnel. Denis Ayoub recalled the first time it happened to him, when he was behind another sapper who was leading in the exploration of a narrow communications tunnel:
"One minute we were crawling through the tunnel, the next minute my mate, without a word, started to back up rather rapidly. None could turn around in the tunnels we found on Crimp; you had to back out of the bloody things. So he started to back up, and I had to back up. None said anything. When we got to the bottom of the shaft, he somehow managed to get past me and was first up and out. So I came up second, hoping to Christ my legs weren't going to be left behind. When we got out, and my mate cooled down a bit, he told me he'd seen a man down there."

Of all the tunnels intelligence assessments made during Crimp, the Royal Australian Engineers was probably the most accurate and the most prescient. Despite their success, the Aussies were never again to be so involved in the tunnels of Cu Chi.

When the nucleus of 3 Field Troop became 1 Field Squadron, the tunnel war continued for the "Tunnel Rat". 1 Field Squadron was made up of three field troops. 1 - 2 and 3 Troop. Each field troop was designated a specific RAR, Armour etc to support in field operations. The lessons learned in the Cu Chi tunnels by the original 3 Field Troop was carried on by the successive three field troops, and the tradition of the original "Tunnel Rats" was upheld with both courage and distinction. The whole of the Corp of the Royal Australian Engineers owes Capt McGregor a debt of gratitude for the way he documented his procedures for successive Troops to build on for successful tunnel operations within the (TAOR) Task Force Area of Operation in Phouc Tuy Province.

Every engineer carried a flashlight, and they soon learned that it could be both a friend in the darkness as well as a liability. The holder could certainly see what was in its beam, but it presented a very good target to anyone on the other end of it. The "rat" would come to a corner or bend in the tunnel system, and poke the torch around the bend first. Better to have a wound to the hand than the obvious alternative. Feel became the sense that developed quickly. Replacing a broken bulb became second nature. The sense of smell became acute. ( I can still smell Asian when I walk into a shop. I can still smell them before I see them, and I have no doubt that they too learned to smell us before they saw us.) It is these heightened senses that saved many lives underground.

The use of weapons underground was a hotly contested debate. For my part, I never discharged a pistol underground. No doubt those who did still hear the ringing in the ears due to shattered eardrums as a result. A heavy Colt 45 was a cumbersome appendage, but still some sappers (rats) carried them. I personally carried a Browning 9mm. It was standard Australian Army issue. It had a low muzzle velocity and was lighter in construction than other pieces, and if the ammunition was changed regularly, there was little chance of a misfire. One only had to remember to freshen up the ammunition on a regular basis, otherwise it was possible to end ones tour with the same bullets that one started with. Not that I didn't come across enemy activity while underground. My tactic was to shut everything down and wait for them to come to me. The hunter becomes the hunted becomes the hunter. Rely on the fact that they be more afraid of you, than you are of them. I have always believed that the dark was a friend, and I was never disappointed.

Besides, the primary task in the tunnels was to clear them of booby traps etc, locate equipment, gather intelligence and deny the enemy the further use of the equipment and the tunnel system by its total destruction. It is at this point that discussion must be had regarding what constitutes a tunnel or tunnel system.

An bunker system, connected by short to medium tunnels (10 - 50metres in length) should be considered a tunnel complex. It could be considered a complex bunker system and not a tunnel complex. I consider a tunnel to be a underground passage where the light from the entrance can't be seen from the point of exit. I have been in systems that stretch for hundreds of metres interspersed by elaborately constructed fortified fighting bunkers no more than 50metres between bunkers. If I could turn off my torch and see no light from either end, then it was considered a tunnel. If some consider that this type of complex is not a tunnel system per se, then some engineers may not be entitled to call themselves "Tunnel Rats". Maybe we should be called bunker rats.

Most of the complexes found in Phouc Tuy Province fell into the above category. ie: Enlarged bunker systems linked by short to medium length tunnels. There were longer tunnels, but none of the extent of those found in Cu Chi. That complex was a one off situation. Other large complexes were located and destroyed, but none were as extensive as the Cu Chi tunnels.

We lost a lot of good engineers, but the cost could have been higher without the efforts of men like Sandy McGregor. I never had the pleasure of meeting Sandy but I served with his brother Chris in 3 Troop in 1969-70. Chris was a great engineer, and if his brother Sandy was half as good, then their father should be a exceedingly proud man indeed.

There are several books written about tunnel warfare, but I have yet to find a definitive one that tells the whole story. Every one lacks the overview. Most concentrate on a specific and mostly detailed time or event. Until someone writes a book that covers all aspects of the involvement of both the Americans and the Australians in Tunnel Warfare in Vietnam, then the arguments will always be unanswered.

Most of the above data was extracted from various sources. Some information was obtained from Sandy McGregor's book "No Need for Heroes". Some was downloaded from sources unknown and some text was edited or rewritten. If anyone has anything to offer to expand this subject, please get in touch with the VSASA at the email address below. All email will be responded to.

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Copyright 1997 VSASA
Last modified: September 27, 1998