The Tunnels of Cu Chi (33 page)

Sergeant Bill Wilson, the tunnel rat in the 1st Infantry, used to examine tunnels after they'd been “destroyed” by explosives. “They were putting crates of the stuff down there and setting it off—it didn't do anything. All it did was put cracks in the walls, made a hole here or there, but it didn't do anything to the major structure of it.” Tunnel rat Bernard Justen has kept the photographs of the “damage” done by 40-pound cratering charges. They show walls that failed to collapse, because the laterite clay had set so hard, it was like concrete. In fact, many tunnel rats originally were convinced that concrete had been used in tunnel construction, whereas it was merely the rock-hard clay. Gilbert Lindsay, the Japanese-American rat with the 25th, said that the use of grenades simply “shuffled the dirt.” A little more scientifically, his squad tried a mixture of explosives, digging holes and planting many explosives, sawing through wooden support beams with chainsaws, and carefully “imploding” strategic tunnel sections. (They would then retire at night because it was unsafe to stay on the site.) To their dismay, from the relative safety of their nearby Fire Support Base, they could hear the Viet Cong reconstructing the tunnels.
“They were very ingenious little people. They don't say no.”

Brigadier General Ellis W. Williamson, commander of the 173rd Airborne during Operation Crimp, expressed his feelings about the impossibility of tunnel destruction in a vulgar but succinct way: “It's almost like trying to fertilize a forty-acre field with a fart, or fill the Grand Canyon with a pitchfork. You just work and work and work, and blow up and blast and work more, and the tunnel system's still there. They were so vast and so deep, and there were so many of them, it became a physical impracticality.” The general was still angry about this failure. The reason for it was not only technological failure by the Americans (who, after all, used more bombs in Vietnam than were used throughout all of World War II), but also the fact that the tunnels were an ingrained part of Vietnamese culture, a fabric that they were able to draw round their bodies like clothing. It is a metaphor with which Ho Chi Minh would not have disagreed.

Not surprisingly, indeed on cue, to counteract the growing despair about tunnel destruction, the scientists began to return to the center of the stage. This time they'd come up with the ultimate bang—a new liquid explosive for destroying tunnels. On 5 October 1968, a Big Red One tunnel rat squad under Lieutenant Earl H. Culp was flown to a 300-meter “test” tunnel, one that had been uncovered a year earlier and abandoned by the VC. The rats, long since inured to the eccentricities of the enthusiastic young scientists, were ordered to cooperate. They flew in at eleven in the morning and by one-thirty had charted the tunnel and set standby explosive charges of C4 in a smaller tunnel, adjacent to the main one. They'd been told the scientists with the new liquid explosive would be on site by three-thirty. But by dusk no one had turned up. In some annoyance at having their time wasted in this way, the rats spent the night at a nearby 11th Armored Cavalry night defense position, returning to the tunnel the next morning. Eventually the men from the Concept team USARV (United States Army in Vietnam) turned up, together with the new invention. The rats graciously allowed them to do the work. By eleven-fifteen the system was set up and the liquid explosive was pumped into the tunnel entrance. After exactly two minutes, the hose became twisted and pumping had to stop. Subsequently, the hose repeatedly snarled and
fouled. The rats sat by, smoking, sunbathing, or snoozing. Increasingly nervous, unaccustomed to the midday heat, and dubious about their equipment, the Concept team decided to call it a day and blow whatever explosive had already been pumped into the tunnel. Unfortunately, when they tried this, the booster charge went off but the main charge failed. The Concept team now gently asked the rat squad for a little help. Could they explore the tunnel and find out—in the cause of science—what had now gone wrong? The rats pointed out that the tunnel was polluted by the booster charge. There was a long wait until gas masks were flown in. A check of the system showed that the hose and the firing wires had become hopelessly entangled inside the tunnel. It took the rats an hour to untangle the twists and repair the hose, and that being accomplished, the Concept team, now somewhat revived and emboldened, decided to go for another test shot. The rats were unhappy about this but were overruled. When the Concept team detonated the test shot, the entire tunnel system exploded, injuring three members of the tunnel rat squad. A fistfight between the rats and the scientists was narrowly averted. The rat squad, carrying their injured, were airlifted back to Lai Khe. The Concept team went back to their offices, and the revolutionary new liquid explosive was withdrawn.

The use of gas to destroy or pollute tunnel sections achieved some degree of success. The most popular was acetylene. “Mighty mite” commercial air blowers pumped the highly volatile gas into the tunnel system from the generators that manufactured it, after attempts had been made to seal all possible tunnel exits and ventilation holes. Then one or two pounds of ordinary explosive would be placed near the tunnel entrance and detonated, causing—with luck—a chain explosion through the tunnel. But there were limitations. The trapdoor seals prevented the gas from spreading very far, gas did “bleed” out of the tunnels, blow-backs sometimes destroyed the generators, and skilled and trained soldiers had to be used to operate the system. Moreover, one double generator provided sufficient gas to destroy only fifty meters of tunnel, at a depth of five to seven feet. In early comparative tunnel-destruction tests by the newly arrived 25th at Cu Chi, explosives were at first thought to be superior. The amount of equipment necessary to destroy just one 500-meter tunnel is instructive:

All this was needed for only 500 meters of tunnel, yet there were 150
miles
of them to be located and destroyed if the Americans were to win the war in the tunnels.

Needless to say, it did not take long for the scientists to get back in on the act. They figured that the problem lay with the size of the generators and mighty mite air blowers; in their minds bigger would be better. After due deliberation, they recommended field trials for three new gasoline-driven air blowers, now grandly renamed Tunnel Flushers. They were the Model K Buffalo Turbine, the Mars Generator, and the Resojet.

The supposedly portable Buffalo Turbine weighed, incredibly, 800 pounds. The Mars weighed 175 pounds, but used six gallons of gasoline every thirty minutes. The Resojet needed two strong soldiers to cart it around and it also had an insatiable thirst, drinking two and a half gallons of gasoline every fifteen minutes. It could not be refueled during operation. The tunnel rats watched the combat field tests with growing amusement. The sight of 800-pound tunnel flushers being manhandled through rice paddies, swamps, and jungle, in temperatures of 100 degrees with saturation humidity created only sympathetic headshaking among the handful of professionals who watched from the sidelines.

The word soon got out, and the grunts found themselves suddenly unwell when it came to handling the grotesquely overweight Buffalo Turbine. Flying it around on helicopters and then humping it onto APCs or jeeps to try to get it near tunnel entrances became so impractical that the turbine was quietly abandoned.

The Resojet fared little better. Smaller, lighter, it was nevertheless ill-adapted to the jungle. When a squad from the South Korean contingent tried it out at an accessible tunnel entrance in a deserted village, it wouldn't start in the heavy rain. The
Mars Generator did at least make first base, but it was suddenly discovered that the products of combustion were blown into the tunnel at a temperature of 1000 degrees Fahrenheit. “This is considered to be unsafe if friendly personnel are in the tunnel,” noted an army report dryly. The tunnel rats thought so, too, and pledged to stay well away from it. Although the Mars received a qualified “go” for Vietnam, it was the little “mighty mite” that endured.

In the end it was human—not scientific—ingenuity that proved most effective against the tunnels. The best way of dealing with them was almost certainly worked out by a young marine lieutenant colonel who discovered a few tunnels in his sector near Chu Lai, near the DMZ. Lieutenant Colonel Oliver was a battalion commander with Task Force Oregon, a division-sized force then under the command of Major General Richard Knowles, who told Oliver's story ruefully, and with an acute sense of hindsight.

Colonel Oliver had been chasing a Viet Cong company near Quang Nhai without any success. The company was locally drawn and was causing havoc. Oliver's battalion had spent fruitless weeks hunting the elusive Communists, embarrassed that a company-sized force was able to play cat-and-mouse with a full U.S. battalion. Early one morning, during an extensive sweep, his men found a series of bunkers and tunnels. Oliver concluded, correctly, that this was probably the base for the VC company. There were no tunnel rats with the battalion, nor was anyone with tunnel warfare experience available. Most battalion commanders would probably have called for an artillery or air strike, tossed a few grenades into the holes, and reported the VC company destroyed. Colonel Oliver was not that sort of marine. He embarked on a crash program to teach his men how to identify hidden bunkers, ventilation shafts, tunnel entrances. He instructed his officers to teach the men how to probe for tunnels, using bayonets where appropriate, or metal rods. He carefully mapped the location. He could have turned for help to the scientists, but he ignored them.

Only after the training had been done did he approach his commanding general and ask for permission to conduct the operation. Knowles agreed. The plan was simplicity itself. The entire area would be seized and held for as long as it took. Perimeter security would be established and maintained, come
what may. Then the
entire battalion
would cover the ground, inch by inch, like policemen searching for a murder weapon in the undergrowth—only the GIs would be probing and eye-balling for tunnels. In this arduous, time-consuming, and dangerous way, they found all the tunnels. The operation was a complete and unique success. General Knowles claims that nothing like it had ever happened in South Vietnam. The whole VC company was dug out, and in a series of small firelights and subsequent surrenders, eighty-nine out of a company of ninety-two were killed, wounded, or captured. “We know those figures were right,” said Knowles, “because we caught the VC company commander and made him go through his own personnel list, which we checked against the dead and the captured, name by name. It was tremendous. I became very enthusiastic about this technique. General Abrams had just been assigned deputy MACV, and we briefed him on it, and he became enthusiastic.”

It was now August 1967. The operation generated considerable paperwork, and Colonel Oliver was asked to help establish a Tunnel School, where these simple and effective tactics could be taught. There was, however, no serious tunnels problem in the northern area, the I Corps Tactical Zone. The news of this tactic evidently failed to filter south to the increasingly frustrated commanders of the 1st and 25th Infantry, continuously fighting to pacify the hostile countryside of the III Corps Tactical Zone and defend Saigon, while also trying to consolidate their own base security. Colonel Oliver's work went unrecognized, and in the Cu Chi district the Viet Cong obstinately remained underground.

Major General Charles M. Duke commanded all U.S. Army engineers in Vietnam; his tour of duty ended in May 1968. In his confidential debriefing report for the Chief of Engineers, he wrote: “Counter-tunnel warfare or doctrine is still in its infancy. A number of devices are under development or testing designed to assist in the detection, exploration, and destruction of tunnel complexes. None of these has so far proven to be completely successful. Efforts in that direction should continue … Much remains to be done.” The U.S. Army had already been in Vietnam for three whole years.

   Rat Six and Batman

The special importance of the tunnels was acknowledged by the Americans as their military presence in Vietnam reached its peak—to over half a million men by mid 1968. If some lessons in tunnel warfare remained unlearned, Operation Cedar Falls had at least one noticeable result: the decision not to allow untrained men to explore tunnels. There had been too many “noncombat” deaths underground. After that operation, the commander of the only division with an organized tunnel rat team—the Big Red One—transferred that role from his chemical platoon to the engineers, who were expert in demolition explosives. In June 1967 the Tunnel Rat team was formally created as an offshoot of the intelligence and reconnaissance section of the 1st Engineer Battalion. A lieutenant commanded the team, and he was known as Rat Six, “six” being the division's own codeword for a commander. The 1st Engineer Battalion's commander had the code-name Diehard Six, and the team became known as the Diehard Tunnel Rats.