Cold War, Military

Vietnam Tunnel Rats – The Underground War

In modern military history, the Vietnam War can be observed as a prime example of how guerrilla attacks and seemingly primitive tactics can immobilize a superior force.

To hide from the attacking forces, the Viet Minh and the Viet Cong built extensive subterranean systems. They were essentially underground military bases that needed to be cleared out before the army could move on.

The men who cleared out these underground death traps were commonly known as ‘Tunnel Rats’. This is their story.


Why Were the Tunnels Built?
What Did Vietnamese Tunnels Look Like?
Life in Vietnamese Tunnels
Why Was Clearing the Tunnels Out Important?
Who Were the First Tunnel Rats and How Were They Equipped?

Long before the Vietnam War we know of today, there was a smaller conflict going on in the same area, called the First Indochina War. The French Colonial Forces were battling the Viet Minh – the League for the Independence of Vietnam.

The French were undoubtedly superior to the Viet Minh regarding technology, so the Viet Minh had to rely on their superior knowledge and understanding of the territory to fight the enemy.

To avoid easy detection and death from above, the Viet Minh started digging underground tunnels. In the beginning, the tunnels were nothing more than simple bug-out holes in which the forces could quickly retreat to if they became overwhelmed.

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Then, they would either hide and stay quiet, hoping to avoid detection, or they could make their way to the other end of the tunnel, get out, and hope nobody will be waiting on the other side.

Tunnel Rat
Sgt. Ronald H. Payne entering a tunnel in search of Viet Cong. His only defence is a torch and M1911 pistol.

Basic Survival

In the beginning, the French didn’t realize how the Viet Minh were simply disappearing, so the Viet Minh started relying on their tunnels systems more. This tactic would soon start to pay off and the Viet Minh started turning their tunnels from an easy escape option into an offensive strategy.

They would hide in their tunnels, wait for the French to walk over them, then they’d quietly get out and flank them. The Viet Minh also spread their tunnels more and more, adding sleeping chambers and the rooms necessary for basic survival.

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The tunnels were spread all around the territory, which allowed them to move below the ground without alerting the surface forces.

Later on, when South Vietnam, South Korea, Australia, New Zealand, Laos, the United States, and others got involved in the war, the Viet Cong took over the tunnels and utilized them brilliantly.

What did Vietnamese tunnels look like?

The Viet Cong (the National Liberation Front of South Vietnam) improved the tunnels that were originally built by the Viet Minh.

Firstly, they had to greatly expand them. This allowed them to build entire underground military bases. The bases were so well-made, they were equipped with most facilities any above-ground military base had at the time.

The most advanced tunnels had infirmaries, storage facilities (for food, water, medicine, guns, and ammo), training areas, sleeping barracks, separate offices for their officers, and even ventilation systems.

This allowed the Viet Cong not only to use the tunnels as a method of escape and undetected movement, but as an underground base in which they could spend months without putting themselves at risk.

Tunnel system
A cross diagram of a Viet Cong tunnel system. This one was described as ‘Basic’ U.S. Army

On the surface level, the Viet Cong built many spider holes. These aren’t trap holes filled with spiders, as one might assume from the name, but small holes in which Viet Cong snipers would hide. When a Viet Cong decoy would attract the attention of American or Australian troops, the sniper would pop out of the hole and open fire.

Dead End

Once the unit started returning fire, the sniper would simply retreat into the tunnel and close the door behind him.

To make sure that the intruders don’t know what’s in front of them, the VC built the tunnels in a zig-zag pattern. After crossing just a few yards, the tunnel rat clearing out the tunnel would have to clear a corner, which is extremely difficult to do safely in such tight areas.

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Another way to confuse the tunnel rats was by building false tunnel sleeves – these stretches would lead the tunnel rat into a dead-end tunnel, which the Viet Cong were aware of. They would then close the entrance behind them or follow them and kill them from behind.


The inside walls of some infirmaries were covered with parachutes, which prevented the organisms living under the ground from getting close to the wounded. This greatly lowered the risk of infection.

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The sleeping areas most often used hammocks as beds, usually made from parachutes, and they were located three levels below the ground. This was the most inaccessible part of the tunnels, so the VC could sleep soundly, knowing that they couldn’t be be reached in their sleep.

Tunnel Rat
A Tunnel Rat exploring a hole between “floors” of a tunnel system. This is a larger tunnel! U.S. Army

There were many simple, but effective doors built between chambers to prevent gas and water from coming through. Americans and Australians would try flooding or using gas grenades to try and flush the VC out, but these doors were usually good at stopping the spread of gas and water.

Cooking was a problem as it created fumes, but the Viet Cong dealt with it by building the kitchen near the surface. They would dig small tunnels with remote smoke pipes to get rid of the smoke.

Finally, water was a big issue, but they dealt with it by digging through to a well.

Life in Vietnamese Tunnels for the VC and Tunnel Rats

As you might assume, this tunnel design made the Viet Cong notoriously difficult to detect and even more difficult to attack. They could spend months underground without putting themselves in danger.

If someone wanted to invade the tunnel, they had to deal with extremely confined spaces. Some of the tunnels were so small that soldiers would have to crawl on their stomachs if they wanted to pass through them and they couldn’t even kneel in them.

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It’s also important to note that the Vietnamese were shorter than Americans and Australians on average, so the only soldiers that could clear out the tunnels were the short and thinner ones!

Hard to Kill

However, sacrificing access to running water and fresh air for safety isn’t a walk in the park. In most cases, life in the tunnels was terrible – the Viet Cong were hard to kill, but they had to pay a price for that security.

Since there was little air, most soldiers had trouble breathing and suffered from drowsiness and lack of energy. Even though some tunnels tried to implement ventilation systems, these didn’t work particularly well.

They also had very little food and water – just enough not to starve or dehydrate.

Most importantly, however, they had no access to sunlight. Even when they would leave the tunnels, the Viet Cong would do it at night, so it was completely realistic for a VC combatant to not see sunlight for months on end. This had a massively negative effect on their psyche.

Aside from their basic bodily needs being neglected, the Viet Cong were in direct danger from several illnesses (the most dangerous one being malaria) and dangerous animals, such as venomous snakes, spiders, and insects, while disease-carrying rats were also the cause of much trouble.

All in all, it was a terrible life to live, but it was the most effective way of preventing the enemy from finding them. And when they did find them, the tunnel rats had to navigate a plethora of creative lethal traps to clear out the tunnels.

Why was clearing the tunnels out important?

It was the job of the tunnel rats to flush out the enemy from their underground bases. Although they could just walk across them, set up a permanent guard rotation on all exit points and wait for them to pop out while the rest of the regiment moved across the ground, this was too risky.

Australian Tunnel Rat
Australian soldiers were the first true Tunnel Rats in Vietnam. Operation Crimp, Vietnam.

From a strategic standpoint, it’s very dangerous to leave an enemy behind if you know where they are and how to attack them with effect. They could organise a counterattack or keep digging below the ground, advancing by spreading their tunnels.

This was an odd situation South Vietnam and their supporting forces found themselves in. We don’t see it often in warfare that you can gain ground on the surface, but in a way still not advance. This, however, is exactly what happened in Vietnam – South Vietnam could win all the territory and conquer all the VC bases they found on the surface – the war wouldn’t end until they won the underground war too.

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Bad Morale

Quite simply, you don’t win the battle until the enemy is neutralized or until they surrender. No matter how much territory the troops won, this wouldn’t matter if the enemy was still alive and well, just under the ground.

On the individual level, not attacking the enemy when you have a good shot at them is bad for morale. Knowing that their bases remain unharmed because the enemy doesn’t know how to attack them is good for the other side’s morale.

The Viet Cong found solace and safety in their tunnels, which is another reason why clearing them out was so important. If their forces around the country learned that the tunnels aren’t so safe anymore, morale would plummet.

Who Were the First Tunnel Rats and How Were They Equipped?

The Australian Combat Engineer units were the first tunnel rats – they invaded the Củ Chi tunnels just to figure out what they were, if there was anything of value inside, and to get any useful intelligence they could find.

What they didn’t expect to find was a fully developed underground military base with functional radio equipment, ammunition, battle plans, and plenty of Viet Cong resistance inside.

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Up until that point, it wasn’t believed that the tunnels were equipped well enough or important enough to risk lives for their exploration.

Quickly after the Australians took the first dig at the tunnels (pun intended), the Allied Forces Commander requested special training for soldiers who wanted to invade the tunnels.


Their loadout was minimal – keep in mind that the tunnels were very confined spaces. The ‘rat’ would bring a handgun, a flashlight, a knife, and a piece of string with him. Usually no pack containing food or water was brought, as it would only get in the way.

In the beginning, tunnel rats were armed with the M1911 or the M1917, respectively. Both of these handguns use .45 cartridges, meaning that they’re very loud.

Upon firing such a powerful weapon in extremely confined spaces, the hearing of a tunnel rat would be temporarily impaired at best, or they’d become deaf (temporarily or permanently) at worst.

Since it was pitch black in the tunnels, they had to rely on their hearing as much as they did on their eyesight.

Because of that problem, they quickly made the switch to handguns of the .38 calibre, often with suppressors.

The tunnel rats themselves were usually very short (for an adult man) – about 165 centimetres (5 feet and 5 inches) or shorter. Larger men had a lot of trouble moving around the tunnels given how confined they were.

According to Mangold and Penycate, the majority of US tunnel rats were of Puerto Rican or Mexican descent, as they’re naturally shorter than people of European descent.

It was the job of these men to invade the tunnels, bring out useful intelligence, and clear the tunnels out.

How did Tunnel Rats clear the tunnels out and what traps did they face?

It could take days for tunnel rats to clear out a single tunnel system – it often took more than a single tunnel rat to clear out a tunnel, as this was an extremely dangerous job and many tunnel rats died on their first underground venture.

Viet Cong
A Viet Cong soldier crouches in a tunnel system with his SKS rifle at the ready.

These men were invading extremely dark and confined spaces without knowing anything about the inside of the structure itself. The most dangerous aspect of the mission, however, was the fact that the entire tunnel was often rigged with lethal traps.

Aside from the garden variety anti-personnel mine or fragmentation grenades with a string tied to the pin, the Viet Cong employed very creative traps.

The most well-known ones are the Punji stick traps. Punji sticks are sticks made from bamboo or some other wood that were sharpened enough to stab a person. There’s plenty of bamboo in Vietnam and the sticks were easy to sharpen, so these traps were quick and simple enough to make.

They would dig a hole, dig the sticks into the ground and cover the hole – the tunnel rat would simply fall in and get impaled on the sticks. Another method was attaching them to a pressure-sensitive or a string trap. The tunnel rat would activate the trap and the sticks would lunge at him.

Flooded Tunnels

Some tunnels would have a built in U-shaped sleeve that they’d flood once the tunnel rat was at the bottom – it would be extremely difficult to swim up in those conditions and tunnel rats would often drown.

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They also dug small chambers covered with fake walls – they could watch the tunnel rats as they came closer and either shoot them or stab them with a spear. Sometimes, they’d purposely build an ‘obvious’ chamber door which the tunnel rat would open and crawl in head-first. A VC fighter would grab him around the neck with garrotte wire and strangle him.

Snake Pits

Animals were also used for the traps – snake, scorpion, and spider traps were all very common. The snake trap was perhaps the most fearsome one – the Viet Cong would tie a bamboo pit viper (Trimeresurusstejnegeri) down to a hidden hatch in the tunnel ceiling. The tunnel rat would trigger a string or a pressure pad and the hatch would open, the snake would hang from the ceiling and it would most likely bite the soldier.

The tunnel rat could shoot the snake, but that’d just warn the VC of his position.

They also used snake pits, which are exactly what you think they are – hidden pits filled with bamboo pit vipers (personally, my worst nightmare). The venom of the bamboo pit viper is very potent, and in some cases, it can cause a painful death if no antivenin is applied.

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Direct Combat

As you can imagine, these traps weren’t only lethal, but they had a disastrous effect on morale as they completely diminished any motivation a soldier might have had before. Knowing that you’re walking into a maze of traps without knowing what they are and where they are, having to rely mostly on improvisation and quick thinking, while being unable to see, breathe, eat, or drink more than the bare minimum was a terribly mentally draining job.

The only positive, if any, is that the tunnels were so confined, if it ever came to direct combat between a tunnel rat and a VC, it would always be 1 on 1 combat. There was simply not enough space for more Viet Cong to surround the tunnel rat, so the tunnel rats didn’t need to worry about being outnumbered (unless they entered a large chamber, such as the barracks).

All in all, it was a terrible duty to be saddled with, but somebody had to do it.

Were Tunnel Rats Sacrifices Worth it in Retrospect?

Sadly, the majority of tunnel rats did not return home. It can be thought of as one of the deadliest jobs in the military, which begs the question – when you take a look at the big picture, were the sacrifices worth it?

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Admittedly, the question is difficult to answer. Tunnel rats found a plethora of useful intelligence in the tunnel systems, and in that regard, it can certainly be said that they helped the war and kept their comrades on the surface safer. At one point, they found out that the VC were successfully decoding their messages. Information like this is crucial in a war and it explained why the Viet Cong were always one step ahead.

They also confiscated weapons, ammunition, and captured the enemy.

Tunnel rats had some one of the most dangerous jobs and, in my opinion, the most nerve-wrecking job in military history. The tunnels they invaded had rendered all their superior technology useless and they had to rely on basic gear, reflexes and a cool head, all while knowing that the enemy was expecting them.

It’s difficult to answer whether the sacrifices were worth it, as the only people qualified to answer that question are the ones who made the sacrifices.

What I can tell you is that what these men did is incredible and, for most people, unbelievable.