Why the Viet Cong’s Tunnels Were So Deadly And Highly Effective

While a buddy, with pistol ready, kneels by, a G.I. of the 2nd Battalion, 18th Infantry, shovels dirt into a tunnel entrance where Viet Cong were believed to be hiding. (Photo Credit: Bettmann / Getty Images)
While a buddy, with pistol ready, kneels by, a G.I. of the 2nd Battalion, 18th Infantry, shovels dirt into a tunnel entrance where Viet Cong were believed to be hiding. (Photo Credit: Bettmann / Getty Images)

Of all of the nasty, uncomfortable, deadly, and outright terrifying jobs carried about by those who served in the Vietnam War, clearing Viet Cong tunnels was one of the worst. The task emerged from the Vietnam War as one of the most dreaded jobs of the conflict, and there is no surprise why.

These tunnels were vast and complex, often dimly lit and vulnerable to collapse at any time. The Viet Cong (VC) dug and used the tunnels for many purposes – namely as shelters and as support networks – and they were critical to the guerrilla war they waged. Due to their importance, they had to be cleared by US forces as they moved past them. Often this was done by hand, by troops who were unofficially known as “tunnel rats.”


Vietcong Tunnels
Entrance to a VietCong tunnel. The former Viet Cong guerrilla camp 75km north of Saigon (Ho Chi Minh) known as ‘Cu Chi’ was the largest underground tunnel network in the Vietnam war. Over 175 miles of tunnels were constructed and used by the Viet Cong. The camp was completed 40 years ago in 1967 and was home to over 16,000 Viet Cong at the time. (Photo by Giles Clarke/Getty Images)

These primitive constructions were incredibly important to the Viet Cong during the war. The groundwork of the tunnels was laid by the Viet Minh while fighting France’s colonial control and was expanded upon by the Viet Cong. Inside, these tunnels stretched for miles and contained hospitals, ammunition and equipment stores, living areas, headquarters, and fighting positions.

Stores of food and water and complex air ventilation systems meant VC troops could live and work in the tunnels for months. Often, troops would stay in them in the day and only come out at night for military operations or to care for crops and gather supplies.

The vast network was accessed by expertly camouflaged entrances dotted all over the jungles of Vietnam. These weren’t only access points, but tactical tools during combat. When fighting the enemy, the VC seemingly had the ability to disappear into the jungle. In reality, the troops withdrew from the action into the tunnels, which were often impossible to locate.

A tunnel in Vietnam
Inside a VietCong tunnel. (Photo Credit: Giles Clarke/Getty Images)

From here they could relocate to a different position to continue the fight. This method of constant relocation was tough to counter. US troops were forced into what was essentially a large, deadly game of wack-a-mole.

Furthermore, the VC could wait until American forces passed overhead, pop up from the tunnels, attack from behind, and then return to hiding. They helped create devastating ambushes.

The entrances themselves were, as mentioned, were usually impossible to spot by an untrained eye. They could be blended into the jungle floor or hidden under sacks of rice and heavy cooking pots. Some entrances were positioned near villages so any track marks would blend into the normal village traffic.

Vietnam Tunnel Entrance Hidden
Hidden trap door to Viet Cong tunnel. (Photo Credit: Giles Clarke/Getty Images)

The tunnels enabled the VC to relocate vast quantities of men and supplies over large distances without any interruption, retreat without being pursued and protected those inside from the US’ formidable air power.

While they were incredibly efficient in terms of waging war, the tunnels were not nice places to be for the VC.

Dug straight out of the soil of Vietnam, they were infested with venomous snakes, spiders, and scorpions, as well as diseases and poor air quality. Furthermore, those operating inside the tunnels were exposed to high quantities of chemicals like Agent Orange, which leached through the soil from the surface. Some tunnels were crudely built and were at risk of collapsing straight down onto their inhabitants.

Naturally, the scale and convenience of the tunnels were a real problem for America and its allies, who continuously tried to hamper their use.

Countering the tunnels

Vietnam Tunnel Rat
Vietnam War 1968. American soldiers uncover a Vietcong tunnel. (Photo by: Universal History Archive/Universal Images Group via Getty Images)

When the US first ran into the tunnels, officials decided that brute force was the best solution to destroy them. Operations like Operation Crimp saw thousands of troops search the jungles of Vietnam for the tunnels. Any that were found were either “crimped” with explosives or had gas or water poured into them. However, it was soon found that these methods didn’t work.

The tunnels had been specifically designed to prevent water or gas from flowing through them and reduce the effects of explosives detonating inside. It wasn’t until Australian troops explored the tunnels that their full complexity and scale were revealed.

After this, the US changed its tactics for dealing with the tunnels; now troops had to search them by hand.

Volunteers started establishing techniques and methods for exploring the tunnels, which were often about as wide as a man’s shoulders. Due to the cramped conditions, men of a small stature were ideal. Tunnel rats were armed only with a flashlight and a small weapon like a handgun.

Vietnam Tunnel Entrance
Cu Chi Tunnels (near Saigon City). (Photo by Jose-Fuste RAGA/Gamma-Rapho via Getty Images)

When the tunnel rat was inside, they faced a whole host of dangers on top of what was already facing the VC living in them. The tunnels were engineered to be a nightmare for infiltrators. They were booby-trapped with spikes, grenades, poison gasses, trap doors, snakes, and even sections that could be flooded with water.

The tunnel rat had to silently make his way through the tunnel, often in pitch black, keeping an eye for booby traps or VC troops. Many tunnels were cleared by these brave men, but for the most part, they remained widely accessible to the VC throughout the war.

Tunnel Map in Vietcong Tunnel
Cu Chi tunnels, Sud Vietnam, Asie. (Photo Credit: Didier NOIROT/Gamma-Rapho via Getty Images)

Many veterans of Vietnam can agree this terrifying job was one of the worst of the war.

Jesse Beckett

Jesse Beckett is one of the authors writing for WAR HISTORY ONLINE