By the time Cal Dexter reached Vietnam, they had been in existence for three years, the only unit whose Purple Heart ratio was 100 percent.

The commanding officer of the moment was known as Rat Six. Everyone else had a different number. Once joined, they kept to themselves and everyone regarded them with a kind of awe, as men will be awkward in the company of one sentenced to die.

Rat Six had been right in his gut guess. The tough little kid from the construction sites of New Jersey with his deadly fists and feet, Paul Newman eyes, and steel nerves, was a natural.

He took him down into the tunnels of Cu Chi and within an hour realised that the recruit was the better fighter. They became partners underground where there were no ranks and no "sirs," and for nearly two tours they fought and killed down in the darkness until Henry Kissinger met Le Duc Tho and agreed America would quit Vietnam. After that there was no point.

To the rest of the Big Red One, the pair became a legend, spoken of in whispers. The officer was "the Badger" and the newly promoted sergeant was "the Mole."

5 The Tunnel Rat

In the army, a mere six years in age difference between two young men can seem like a generation. The older man appears almost a father figure. Thus it was with the Badger and the Mole. At twenty-five, the officer was six years older. More, he came from a different social background with a far better education.

His parents were professional people. After high school he had spent a year touring Europe, seeing ancient Greece and Rome, historical Italy, Germany, France, and Britain.

He had spent four years in college getting his degree in civil and mechanical engineering before facing the draught. He, too, had opted for the three-year commission and gone straight to OCS at Fort Belvoir, Virginia.

Fort Belvoir was then churning out junior officers at a hundred a month. Nine months after entering, the Badger had emerged as a second lieutenant, rising to first when he shipped to Vietnam to join the First Engineer Battalion of the Big Red One. He, too, had been headhunted for the Tunnel Rats, and in view of his rank, quickly became Rat Six when his predecessor left for home. He had nine months of his required one-year Vietnam tour to complete, two months less than Dexter did.

But within a month it was clear that once the two men went into the tunnels, their roles were reversed. The Badger deferred to the Mole, accepting that the young man had a sense for danger, the silent menace around the next corner, the smell of a booby trap, that no college degree could match and which might keep them both alive.

Before either man had reached Vietnam, the U. S. High Command had realised that trying to blow the tunnel system to smithereens was a waste of time. The dried laterite was too hard, the complex too extensive. The continuous switching of the tunnel direction meant explosive forces could only reach so far and not far enough.

Attempts had been made to drown the tunnels with flooding, but the water just soaked through the tunnel floors. Due to the water traps, gas failed as well. The decision was made that the only way to bring the enemy to battle was to go down there and try to find the headquarters network of the entire Vietcong War Zone C.

This, it was believed, was down there somewhere, between the southern tip of the Iron Triangle at the junction of the Saigon and Thi Tinh Rivers and the Boi Loi Woods at the Cambodian end. To find that headquarters, to wipe out the senior cadres, to grab the huge harvest of intelligence that must be down there-that was the aim and, if it could be achieved, a prize beyond rubies.

In fact, the headquarters was under the Ho Bo Woods, upcountry by the bank of the Saigon River, and was never found. But every time the tankdozers or the Rome Ploughs uncovered another tunnel entrance, the Rats went down into hell to keep looking.

The entrances were always vertical, and that created the first danger. To go down feet first was to expose the lower half of the body to any VC waiting in the side tunnel. He would be happy to drive a needle-pointed bamboo spear deep into the groin or entrails of the dangling GI before scooting backward into the darkness. By the time the dying American had been hauled back up, with the haft of the spear scraping the walls and the venompoisoned tip ripping at his bowels, his chances of survival were minimal.

To go down head first meant risking the spear, bayonet, or pointblank bullet through the base of the throat.

The safest way seemed to be to descend slowly until the last five feet, then drop fast and fire at the slightest movement inside the tunnel. But the base of the shaft might be twigs and leaves, hiding a pit with punji sticks. These were embedded bamboo spears, also venom-tipped, that would drive straight through the sole of a combat boot, through the foot, and out the instep. Being fishhook carved and barbed, they could hardly be withdrawn. Few survived them either.

Once inside the tunnel and crawling forward, the danger might be the VC waiting around the next corner but more likely the booby traps. These were various, of great cunning, and had to be disarmed before progress could be made.

Some horrors needed no Vietcong at all. The nectar bat and black-bearded tomb bat were both cave dwellers and roosted through the daylight in the tunnels until disturbed. So did the giant crab spider, so dense on the walls that the wall itself appeared to be shimmering with movement. Even more numerous were the fire ants.

None of these were lethal; that honour went to the bamboo viper, whose bite meant death in thirty minutes. The trap was usually a yard of bamboo embedded in the roof, jutting downward at an angle and emerging by no more than an inch.

The snake was inside the tube, head downward, trapped and enraged, its escape blocked by a plug of kapok at the lower end. Threaded through this was a length of fishing line, heading through a hole in a peg in the wall on one side, thence to a peg across the tunnel. If the crawling GI touched the line, it would jerk the plug out of the bamboo above him and the viper would tumble onto the back of his neck.

And there were the rats, real rats. In the tunnels they had discovered their private heaven and bred furiously. Just as the GIs would never leave a wounded man or even a corpse in the tunnels, the Vietcong hated to leave one of their casualties up above for the Americans to find and add to the cherished "body count." Dead VC were brought below and entombed in the walls in a foetal position before being plastered over with wet clay.

But a skim of clay will not stop a rat. They had their endless food source and grew to the size of cats. Yet the Vietcong lived down there for weeks or even months on end, challenging the Americans to come into their domain, find them, and fight them.

Those who did it and survived became accustomed to the stench as well as to the hideous life-forms. It was always hot, sticky, cramped, and pitch dark. And it stank. The VC had to perform their bodily functions in earthenware jars; when full, these were buried in the floors and capped with a plug of clay. But the rats scratched them open.

Coming from the most heavily armed country on earth, the GIs who became Tunnel Rats had to cast all technology aside and return to primal man. One commando knife, one handgun, one flashlight, a spare magazine, and two spare batteries were all that would fit down there. Occasionally a hand grenade would be used, but these were dangerous, sometimes lethal for the thrower. In tiny spaces, the boom could shatter eardrums, but worse, the explosion would suck out all the oxygen for hundreds of feet. A man could die before more could filter in from outside.

For a Tunnel Rat to use his pistol or flashlight was to give his position away, to announce his coming, never knowing who crouched in the darkness up ahead, silent and waiting. In this sense, the VC always had the edge. They only had to stay silent and wait for the man crawling toward them.