The Tunnels of Cu Chi (11 page)

Giang also revealed that the Communists had created a kind of tunnel hierarchy. There were what he called “high-level cadre tunnels,” specially dug by VC engineers and specially reinforced. These were hideaway tunnels for about three cadres at a time and were specially bomb-proofed, using the husks and bamboo. Then there were tunnels for common cadres. These had to be made “by the individuals themselves … further there were no bamboo walls inside.”

But even if accommodations were graded to some extent, the fact remains that by accident, design, or a combination of both, the Communists did create a series of underground fortifications strong enough to withstand most types of destructive warfare. For the Americans the sheer military frustration of dealing with the tunnels was to become intense. It was as if Goliath had
both
the club and slingshot, while all David did was dig a hole and hide, pop up every now and then to fight, and run.

The tunnels were usually dug the hard way—by hand. The tunnels manual tried somewhat patronizingly to formalize a system. It announced:

There was a primitive earth-lifting device that stood over tunnel holes during digging and allowed semimechanical earth
removal
, but not excavation.

Major Nguyen Quot is today with the 7th Military Region headquarters in Ho Chi Minh City. As a young captain (promotions in the People's Army are remarkably slow), he was assigned to the tunnels of Cu Chi. Like Captain Linh, he was
to spend five years on that assignment. His eyes were to suffer badly from lack of light, and today he rarely removes his heavy sunglasses. Although the work norm for earth excavation was about one cubic meter per person per day, this obviously varied with the digger's health, age, the climate, and the soil. In Major Quot's experience only about half a cubic meter of dirt was excavated per working day, “although near a ventilation hole, they could dig faster and get more out.” He says that everyone took part in the digging of the tunnels: old men, women, young men, and girls, even children. The process for earth removal was reasonably simple. A drawing hanging at Phu My Hung shows the method quite clearly. First a shaft was dug from the surface down three to five meters. A laborer would remain at the mouth of the dry well, as the first hole was called, with a basket attached to a long stick. The tunneler would place earth in the basket, which was then hauled up. At the same time a similar process would begin some ten meters away from the first dry well. Once both tunnelers had reached the required depth, they would begin tunneling toward each other underground. They relied on sound alone to help them meet in the middle. According to Major Quot, “Our tunnelers had good ears; they always met, and if they were a few centimeters out, it did not matter. Each dry well was filled after it had been dug, and remember, we could never tunnel up because you could not dispose of the earth. It was always down. In order to deal with the rains we allowed a slight downward gradient in the communication tunnels, so the water drained into the wells.”

“To dig the tunnels we divided the work scientifically,” explained Captain Linh. “Old men made baskets for carrying the earth, old women did the cooking, young men and women used their strength to dig the earth. Even children did their share by gathering leaves to cover the trapdoors. Our favorite digging tools were old worn-out spades and old hoes. A new hoe is about fifteen by twenty five centimeters, but after it has been used by the peasants to dig earth in the fields for a long time, it's nicely reduced to the size of a bowl.”

The Saigonese poet and writer Vien Phuong spent much of the war in the tunnels. He is a medium-sized man with graying hair, scrawny arms, and tired eyes behind thick-lensed glasses. In 1962 he was working with the Viet Cong in the countryside.
He was fitter then, he comments, smiling. Today, at fifty-five, he is painfully thin. “Digging tunnels was our daily task; besides the tunnel where I lived, I had to have two or three spare tunnels, because if the enemy came to one, or bombings destroyed the other, I still needed one to go to. So we had to dig daily. The soil of Cu Chi is a mixture of sand and earth. During the rainy season it is soft like sugar, during the dry season as hard as rock. If I managed to dig down thirty centimeters a day in six hours it was a big achievement. It was easier to dig during the rainy season. I had a hoe as small as a saucer, and I had to kneel or sit down on the ground. I had to find hard soil at the root of a bamboo tree or where there was a termite nest. Such soil could stand the weight of a tank. We dug in teams of three: one dug the earth, the second pulled the soil out, and the third pulled it up.”

And how were the thousands and thousands of tons of earth removed from the tunnels to be disposed of, hidden so that the Americans would not find the telltale evidence? The Communists knew full well that the Americans had spotter planes, and sophisticated new aerial-surveillance techniques that could easily “see” great mounds of freshly dug earth. High-resolution photography combined with infrared sensing techniques were sufficiently refined in the early sixties to pose a serious threat. The tunnels manual did not make a great fuss about earth disposal. It simply said, Get rid of that stuff, using your common sense:

And it was.

Tunnelers refined earth disposal to a new science. When the American B-52 bombing raids first began, the VC simply shoveled earth into the new craters. When U.S. ground patrols or the ARVN troops made disposal awkward, they used trained water buffalo to carry dirt away from tunnel sites. MacDonald
Valentine, who spent nineteen months attached to South Vietnamese Ranger battalions and was stationed at Cu Chi, was told by his Vietnamese scout, Phuc Long, that if enemy pressure left them no other option, they would smuggle earth out under the noses of U.S. patrols inside the common Vietnamese crock that usually contained fish sauce. The crock was the size of a coffee jug, and beneath a layer of fish sauce, the women would hide a bladder full of earth. It was as near as one could get to emptying a lake with a tablespoon.

Every twenty or thirty meters the tunnelers dug a water drainage hole to prevent flooding. It was 20 cm wide, 15 cm deep. But even more importantly, every hundred meters or so, in strategic locations within the tunnels, the special water traps were dug. These stagnant stinking pits, first uncovered during Operation Crimp, served to block the corrosive and often deadly fumes from the smoke bombs and CS riot-gas grenades that the Americans hurled into tunnels in an attempt to contaminate them. In effect, some of the most modern and noxious devices produced by Western chemical-warfare laboratories were often frustrated by the equivalent of a lavatory U-bend in the tunnels. The ordinary trapdoors linking the separate levels were also very effective blockers of gas fumes.

One of the most important secrets kept from the Americans during the entire war, according to Major Quot, was that the construction of the tunnels was such that each section could be sealed off. “The Americans thought that our armed forces were confined to one tunnel and that they were able to kill everyone down there by blowing down gas or pumping down a large quantity of water. But this was not so. It was important that the enemy never understood this.”

In reality, this claim is a mixture of boast and fact. In the early days of tunnel warfare the Americans were certainly not aware of the secret exits. But it soon became obvious that trapped VC were not always being caught at tunnel entrances that were sealed by the attacking GIs. The only possible explanation was clearly the existence of hidden escape routes, which the Americans found only with considerable luck or ingenuity.

Although the tunnels were natural shelters against the U.S. bombing attacks, further special protection became necessary when the bombing increased in ferocity. So the tunnelers dug
conical A-shaped shelters that were geometrically designed to resist both artillery shells and bomb blast. More important, their conical shape acted as an amplifier and magnified the distant sound of approaching B-52 strikes. This was the only real warning tunnel dwellers might get of an imminent attack.

Ultimately, the real security for the tunnel system depended on the precise and cunning use of camouflage. An undated captured VC document advised Cu Chi cadres as follows on the subject:

An informant, code-named TU 10, was placed by American military intelligence somewhere in the Tay Ninh area from January to July 1967. On 28 July 1967 he spoke to his controllers at some length about the continuing success of VC tunnels camouflage, revealing some significant things about U.S. infantry technique when it came to tunnel warfare:

Source TU 10 reported that it was a general rule (although not always adhered to) that foliage used in camouflage must be
changed every three days. Often efforts were made (he did not say with what degree of success) to use “small bushes with many leaves” as camouflage, and where possible, living plant shoots, which would grow and remain green.

But Ngo Van Giang, the VC prisoner who had given U.S. intelligence useful information about tunnel construction, suggested there
were
ways for the Americans to discover tunnels, despite the excellent camouflage. Properly trained eyes could see evidence of trails, tree branches might be broken in the area, grass on both sides of the trails might be crushed, there might be several unexplained high knolls in the area, and in the tunnels area the dirt would be slightly more spongy.

The highly trained American Special Forces soldiers, the Green Berets, were specifically trained to break through even the most adroit camouflage systems. They lived rough, often in VC-dominated areas, and became renowned for their field and combat skills. Several were attached to infantry units that went out on search-and-destroy operations, and the Green Berets' ability to spot tunnel entrances was exceptional. But there were never enough Special Forces liaison NCOs to go round, and, if given the choice, they always preferred to return as quickly as possible to their primary missions.

“The tunnels began from a logical strategy,” explained Major Quot. “First they were for individuals, then for families. Each family had responsibility for its piece of tunnel. Then various huts within the hamlet were joined by the tunnels, and soon we began to build tunnels that connected one hamlet with another. In the end there were main communications tunnels, secret tunnels, false tunnels. The more the Americans tried to drive us away from our land, the more we burrowed into it.

“We even had [street] signs underground so that strangers knew where they were, although guiding strangers [VC and NVA soldiers and cadres] was the responsibility of the local hamlet chief. It was for him to provide guides who would take the people from one district to another before handing them over to another guide.”

As the intensity of the war in Vietnam escalated, Cu Chi district and the Iron Triangle area increasingly became the focus of attention for the frustrated Americans. Unable to dominate or secure these areas, they were to resort to the one factor in the military equation that was always in their favor—the ability
to bring overwhelming firepower to bear upon the land. With artillery and air strikes, using high explosives, chemical defoliants, and CS gas, the Americans pounded the surface, while below, whole battalions of regional and regular Communist troops waited patiently. The earth cracked, groaned, and in places gave way. The landscape changed from jungle to dusty desert; entire villages disappeared and their inhabitants were moved out. But the physical integrity of the tunnels was to survive long enough for a shadow civilian and military Communist administration to live in the tunnels, conducting its business and defying nearly every attempt to force it up and out. It was an extraordinary triumph of the primitive in a decade that saw man walking on the moon.

   Survival Underground