The Viet Cong amassed around 250 kilometers of underground tunnels. This network connected villages, cities, and districts. The tunnels also hosted armament workshops, training depots, headquarters, and a variety of other facilities. They helped conduct military operations on behalf of communist forces. Though Americans, Australians, and New Zealanders claim to know these hideouts existed, they overlooked their size and importance. Equally, these countries failed to understand how difficult it would be to detect and neutralize such networks.
Read on to learn about the crazy booby traps soldiers faced, the creepy crawlies they encountered, and the damaging psychological consequences of such close combat. You can also learn about how these soldiers came about, who opted to become one, how they trained, and what equipment they used. Finally, this list will look at how successful these attempts were in the grand scheme of things. If you are squeamish or hate thinking about claustrophobic conditions, take this as a warning: gruesome facts lie ahead!
What were these tunnels and how did tunnel rat soldiers come about?
During the Second World War, the Vietnamese first constructed underground tunnels to fight Japanese invasion. In the 1940s and 1950s, the Vietnamese expanded these tunnels to hide nationalist guerrillas known as the Viet Ming. These guerrillas were fighting the colonial power of France. Major Nguyen Quot, an officer that spent ten years in these tunnels, notes that by 1948 they “already dug a tunnel system: each family, each hamlet, had a tunnel communicating it with others”. By the time the American army arrived, there were over two hundred kilometers.
Initially, America used hunting dogs to locate the enemy. Once the Viet Cong caught on to what was happening, they began to use the same soap the Americans used. This way, they smelled the same as the GIs and the dogs became unable to locate the enemy. The US army now sought alternate measures. Americans often carpet bombed areas under suspicion to try flushing out the enemy. The bombs caused earthquakes that destroyed the tunnels and their ventilation shafts. If it did not force the enemy out, those inside the tunnels often suffocated to death instead.
In a more direct attempt to seek out the enemy, US soldiers used portable turbines to blow CS gas into tunnel shafts they located. Again, those inside suffocated. Another method frequently used attempted to flood the area so badly that the enemy desperately sought to escape to avoid drowning. Using this tactic, they added yellow dye to the water to enable aerial observers to spot any entrances that ground troops had missed.
Yet, both of these tactics were not as successful as they hoped. What they failed to realize is that many of the tunnels had several layers and doors built into them to help prevent such fatalities. The Viet Cong built drain pipe ventilation shafts every 20 to 30 meters at an oblique angle to prevent flooding. Tunnels were also built in zig-zags to prevent the enemy from pouring in chemicals or shooting bullets over a long distance.
On average, tunnels in this underground network were 1.2 meters wide and only 0.8 to 1.8 metres high. As a result, sending a soldier underground, known as a tunnel rat, was often a final measure if all other methods had failed.
Amazingly, these tunnel rat soldiers were volunteers. Why they volunteered varied person to person, but one American soldier speculated volunteers were trying “sometimes to make up for problematic lives back home or to prove their manhood in truly testing conditions.” The same soldier noted that once rats conquered their fear, “assuming they survived, some even came to like their work… for the rats, the light at the end of the tunnel was usually a VC with a candle.’
In general, volunteers had to have common sense, be exceptionally brave, have an inquisitive mind, and have an even temperament. After all, it was a very stressful and dangerous job. A lot of the time, other soldiers thought these volunteers also had to be a certain type of crazy. In one interview, tunnel rat soldier CW Bowman recalled how his fellow colleagues bet money on the fact he would not live through his whole tour as the job was so dangerous. However, Bowman said that he was never that scared of the tunnels; he was so young he believed he was invincible.
In most cases, tunnel rats were engineers, infantrymen, cavalry scouts, or chemical specialists. They carried out tunnel rat duties as and when they needed in addition to any other duties they performed. A lot of the time it really depended on the size of the soldiers in the infantry division. Of course, the local Vietnamese population designed the tunnels with their own size in mind. Consequently, given the average smaller size of Vietnamese men, tunnel rat soldiers, by necessity, were the shortest, skinniest, and most limber men in the army: a maximum height of 1.58 meters.
Men most often explored these tunnels in pairs. One soldier would crawl about five meters behind the other to minimize the chance of death or injury if their leader activated a trap or a mine. This also allowed soldiers to help find and collect any wounded or dead comrades. The enemy used this to their advantage. In a 1977 interview with the Associated Press, a Vietcong survivor recalled how the Americans wasted so much time pulling their dead back that it gave them time to re-group and prepare accordingly.
As mentioned previously, tunnel rat soldiers were a last-ditch attempt and not the usual go-to solution. Every group would do things differently. If the army located an entrance and needed it explored, the team lowered a tunnel rat into the area to scout out the surroundings. Proceeding cautiously, they moved in enough until a fellow soldier could fit into the tunnel with them. From this point, they were to seek out enemy soldiers or potential hiding spaces where they may have once been.
Generally, while underground tunnel rat soldiers employed a “shoot first, ask questions later” method. If they hesitated at all, it is highly likely they would be the ones to die in such close confines. To avoid running into issues, tunnel rats remained very cautious of the number of shots they fired. After shooting a maximum of three bullets, soldiers would typically reload to avoid letting the enemy know when they were out of ammo.
The army sent in tunnel rat soldiers with the aim of locating the enemy, finding their resources, and cutting off their supplies. During one search and destroy operation, for example, a unit destroyed 6000 pounds of rice, 40 pounds of salt, 8 rifle grenades, 8 bunkers, numerous dwellings, and one 120-foot-long tunnel. One battalion also found an ‘underground complex that covered 2,000 meters and yielded cameras, films, printing presses, and type, in addition to the usual cache of weapons and ammunition.’ Shockingly, a US soldier even uncovered a missing M-48 tank buried six feet deep; the Viet Cong were using it as a command center.
According to studies conducted during the war, after one year of service, the hearing and smell of a typical tunnel rat became sixty percent better than that of an average man. Naturally, their opponents were equally as skilled in this department and so tunnel rat soldiers were careful not to clean too much, or use certain products in case their enemies smelled them coming. They harnessed their newfound abilities to help them with survival because unlike their enemies, they lacked experience in these small dark tunnels.
Overall, tunnel rat soldiers received little, if any, specific training. Some of the basic combat training (BCT) soldiers undertook helped though. BCT included lessons on hand-to-hand combat, chemical-warfare defense, map reading, first aid, bayonet fighting, guard duty, and the use of hand grenades. Most useful for tunnel rats, however, was the experience gained in the dreaded gas chambers. Here, leaders forced soldiers into specific chambers and made to recite their name, rank, and service number. It helped give them the experience and confidence to cope with gas, should they encounter it in combat.
Infantry Advanced Individual Training also helped them to deal more in-depth with other issues. Over eight weeks, soldiers learned about tactical skills, squad and platoon offensive and defensive tactics, and how to use certain weapons. Most helpful for tunnel rats, however, was the brief amount of training time spent detecting, removing, and laying booby traps. Though this article will explore specific examples later, these traps were particularly brutal in the tunnels. Soldiers learned to carefully probe the sides, roof, and floor of the tunnels attentively listening and trying to smell the enemy or look for trap doors.
Some tunnel rats were also fortunate enough to take part in Combat Engineer Advanced Individual Training. Since tunnel rats extensively used explosives to collapse tunnel entrances and destroy what they found inside, combat training was particularly valuable. While it covered a lot of the same things as infantry training, it focused more on map reading, knot-tying, navigation, use of hand and power tools, camouflage, constructing barbed-wire obstacles, mine laying, and mine detection. All useful to the experiences of tunnel rats.
Finally, some of the unique training centers would provide tunnel system replicas. The Tropic Lightning Tunnel Rat School at Cu Chi base camp provides an example of this. The center offered classes designed to show the best techniques of searching, detecting, and destroying hiding places. However, other than being underground, they were actually very different from the real Viet Cong tunnels.
Standard weapons carried by most infantrymen were unsuitable for use in such tight confines. Owing to the need for a flashlight, it was essential that soldiers could aim and fire their weapon with one hand. This meant naturally handguns were most commonly chosen. Lots of tunnel rats used the standard-issue colt. 45 calibers with a seven-round magazine as they were readily available. In 1966, the Army issued six tunnel-exploration tester kits. This kit included a S&W .38-calibre special model 10 revolver with both a silencer and aiming light. However, they were not popular among tunnel rats as the light was unnecessary, and the silencers were too long and did not function well.
A light tunnel exploration kit may also include items such as powdered CS, colored-smoke grenades, insect repellent, protective masks, a field telephone, a compass to plot the route, a telephone wire spool, probing rods, bayonets, a flashlight, entrenching tools to reveal and widen entrances, and a .22-calibre HD or MK I pistol. A heavier tunnel-exploration kit may also include nylon rope, body-armor vests, grappling hooks, work gloves, kneepads, and earplugs. Remote-controlled explosive charges and small smoke grenades kits were primarily to signal exit locations to fellow comrades.
Clothing-wise, it was a good idea to wear tight waterproof items to stop clothing from snagging on obstructions, leather gloves, and, if possible as mentioned knee pads to assist with crawling around. When it comes to headgear, some soldiers wore a helmet or a visored cap along with a microphone and/ or transistor radio attached. One of the other problems soldiers faced is the deafening sound of gunshots echoing through the tunnels. While tunnel rats often wanted to wear hearing protection to help lessen the consequences of this noise and avoid damage to their eardrums, they risked not being able to hear the enemy approaching. As a result, many tunnel rats often avoided using hearing protection while underground.
Despite the superior firepower of the American military, the determination of the Viet Cong was on another level entirely. In the 1940s Ho Chi Minh, one of the founders of the Viet Cong, stated “You can kill ten of my men for every one I kill of yours. Even at those odds, you will lose and I will win”. Secretary of State, Henry Kissinger, perfectly summarised the problem in 1969: “The conventional army loses if it does not win, the guerrilla wins if he does not lose”. The Viet Cong were simply experts at utilizing their surroundings to their advantage. Historians, for example, estimate that booby traps caused around 11 percent of US causalities in the Vietnam War.
Punji stake traps found in the tunnels highlight one of the most disgusting and feared examples of Vietnamese booby traps. Several Viet Cong members knew the American soldiers had boots with plated soles to help prevent injury to their feet. Because of this, they often targeted their legs instead. These soldiers made punji stakes out of heated and sharpened wood or bamboo. Sometimes, they would smear the tip of the stakes with urine, feces, poison, or other contaminants to infect the wound when it penetrated the skin.
Next, the Viet Cong would dig a pit and jam the punji stakes upright in it. If they were feeling particularly cruel they may point the sticks downwards at an angle. The soldiers then camouflaged the pit using natural undergrowth, mud, or crops. The stakes would then spear any soldier that fell into the pit. If the stakes pointed downwards, soldiers became unable to remove their limbs without causing severe damage. In particularly horrendous circumstances, enemy soldiers would dig another pit directly beside it. That way, when a soldier fell into a pit and became trapped, he would call for a colleague who would rush to his aid and collapse into the trap next to it. In 1980, recognizing the cruelty of such devices, the Geneva Convention banned them as weaponry.
The Viet Cong also made use of explosive booby traps and pressure detonated mines. Stories reveal that one American soldier raised his head through a tunnel entrance only to have a piece of metal automatically speared through his neck. Tiger traps were also particularly violent. When triggering a tripwire, a plank weighted with barbed metal spikes and bricks would fall rapidly from the earth squashing the soldier below. The idea, of course, was to scare the men so much that they did not continue to search the rest of the tunnel.
Grenade traps were another form of booby trap placed along the base of tunnels. Communist soldiers would attach one side of the string to a stake in the floor, and the other to the safety pin in the grenade. When an American soldier tripped the wire, the grenade would detonate inside the tunnel. If possible they also used gas to disorient, scare, and suffocate tunnel rat soldiers.
Another particularly horrific tactic became known as the spike ball or the mace. The enemy would litter a concrete ball with barbed spikes. When the soldier tripped the wire, the ball would swing down the tunnel and strike into the face of anyone in the way. Similarly, the bamboo whip was a very traumatic trap. When the soldier triggered the tripwire, foot-long spikes placed all over a long bamboo pole catapulted into the soldier’s face and chest at a rapid speed.
Already well-adapted to subterranean life, many insects and animals of the Vietnamese jungle found the underground tunnels to be a worthy living environment. Huge bees, gigantic rats, centipedes, spiders, snakes, bats, and fire ants (to name a few) plagued these tunnels. One tunnel rat claimed that the booby traps and Viet Cong did not frighten them as much as encountering the local ants. I quote “the half-inch ants have such a powerful bite that to pull them off means losing a bit of skin”.
The Viet Cong used this to their advantage to scare, and even kill, American soldiers. Talking of booby traps, Lt. Jack Flowers recalls how the Viet Cong used tripwires to release boxes of scorpions into the tiny confines of the tunnels. One of his men got stung and came out screaming, refusing to ever go into a tunnel again. Similarly, one soldier recalls how an encounter with the biggest rat he had ever seen led him to continually fire his gun. A colleague dragged him out before he grabbed a ‘frag’ and threw it into the hole too. After this, he refused to ever go into a tunnel again. American soldiers were often prepared for traps that may be on the ground, but they had not prepared for those coming from above.
Snakes were also commonly used traps inside these tunnels. Again, tripwires would trigger the release of snakes hidden somehow inside bamboo sticks, known to soldiers as ‘bamboo vipers’. Sometimes these snakes were even poisonous and so became known as ‘three-step snakes’ because a soldier was only granted three more steps before the venom killed him. Imagine being stuck in a tiny space, panicking, screaming, and trying to escape as a snake slowly wound itself around you.
Archives held in Texas revealed this happened to one unfortunate soldier. Reports state the soldier in question “had no time to scream or to unsheathe his knife, the snake had already knotted tighter around his neck and badly bit his face”. A colleague he worked with recovered his body by dragging his “violet-colored corpse” out of the tunnel. It was a horrendous ordeal to face and brought even the toughest of men to tears.
These tunnels hugelyimpacted American morale as it was difficult to comprehend that the enemy could be hiding just feet away yet were undetectable and unreachable. Frank Gutierrez, for example, served with the US Army in Vietnam from 1967 to 1970 as a rifleman, field wireman, and an ordinance specialist at Chu Chi and Long Binh. When interviewed he stated: “We often wondered how things happened in the night and we never saw what was going on, guys getting their throat cut. Nobody ever knew where these guys were coming from… they pointed out in jungle school that there was a tunnel system… we had numerous tunnel rats, but we never knew exactly where or how extensive or where the entrance was. We just didn’t know. I didn’t know.”
One of the huge psychological issues for tunnel rats was the closeness of combat. Even if they could deal with the claustrophobic conditions, air and artillery support had not prepared them for the type of old-fashioned combat that relied on savage behavior, individual strength, guts, and cunningness. The Viet Cong, with their lack of funding, was more skilled in this area given the necessity of their style of warfare. One Viet Cong technique was to slit a man’s throat or garrotte him as he came up through a connecting trap door; this often did not phase the men.
When it came to Americans, however, some found it difficult to kill when they were face-to-face with the enemy in such tight confines. Naturally, there were only first chances, never second, so some simply killed as they had to. On occasion, they ended up having severe nervous breakdowns and their colleagues dragged them out of tunnels crying and screaming. Sergeant Arnold Gutierrez of the 25th Division stated that after a while they became so tuned to what was happening “that when the other person would flick an eyelid up or down, you really knew he was there, in the corner, not even hiding anymore. Just sitting and waiting. [But] They were the ones you never killed. You just backed out and told them up above the tunnel was cold.”
The United States conducted two major campaigns to search and destroy the tunnel system: Operation Crimp (1966) and Operation Cedar Falls (1967). Operation Crimp hoped to target a key Viet Cong headquarter location believed to be unground. Significant causalities ensued on both sides, but the combined Australian and American forces were unable to fully uncover the extensive tunnel network. Similarly, Operation Ceder Falls attempts to uncover and destroy the tunnel system. This attempt enjoyed more success than Crimp but was short-lived as the tunnels were in working order again within weeks.
Overall, the Vietnamese were very quick to restore damages and continue as if nothing happened. This restoration was pivotal as it enabled some of the key successes enjoyed by the Viet Cong. Mai Chi Tho, brother of Le Duc Tho (a prominent Hanoi Politburo member) highlights how they used the tunnels to infiltrate Saigon. Tho claims the Viet Cong prepared both the necessary troops and assembled the supplies needed in these tunnels to conduct the Tet Offensive of 1968. This offensive is commonly seen by historians as a turning point for American involvement in the Vietnam war.
In hindsight, listening to the Viet Cong talk about their experiences in these tunnels, it appears more training certainly would have benefitted the American cause. One Viet Cong soldier highlighted their lack of discreteness. Tunnel rat soldiers often used flashlights to guide the way and thus warned the enemy of their presence. In fact, volunteers boasted of their ability to change flashlights in pitch black without realizing the damaging consequences of this. Similarly, one American soldier highlighted how they liked to ‘soften things up’ by throwing in one or more hand grenades before sending in tunnel rats. However, as the Viet Cong soldier highlighted, by throwing grenades into the void ahead, or shooting pistols, the noise was deafening and alerted them to their presence.
Needless to say, sadly many of those Americans who did enter the tunnels ended up dying. The exact figure, however, remains unknown as there were no extensive records kept on this exact type of engagement with the enemy. According to archives held by the US government, there were 58,220 US military deaths overall as a result of the Vietnam War. The War also claimed the lives of approximately 200,000 allied soldiers in Vietnam, nearly one million North Vietnamese/ Communist allied deaths, and an incomprehensible number of civilians.