In the 1940s, anti-colonial Viet Minh dug the first Vietnamese tunnels in the Cu Chi district against French colonial authority. Tunnels were often dug by hand, only a short distance at a time. In its original form, Cu Chi Tunnels comprised some simple, fragmental tunnels and vaults which were mainly used for sheltering, hiding confidential documents and weapons. They soon became valuable hiding places for the resistance fighters themselves. The gigantic underground tunnel system connects tunnels among hamlets and communes. Afterward, due to the need for communication amongst hamlets, the underground tunnels were adjoined together to create a complicated and efficient system. Then, this system was continued to expand to surrounding areas including six hamlets in the North of Cu Chi District.

Cu Chi tunnels building

The jungle region’s compacted red clay was perfect for tunnel building, and lay above the water level of the Saigon River. There were still challenging problems when digging tunnels here.  They labored with their hoes and crowbars, and frequently encountered snakes and scorpions. They scattered the soil in the river at night, or spreader it in bomb craters in darkness. American bombing made timber scarce, they had to resort to steal iron fence posts from enemy bases to shore up the ceilings. Tunnels could be as small as 80cm wide and 80cm high; vent shafts (to disperse smoke from underground ovens) were camouflaged by thick grass and termites’ nests. Pepper was sprinkled around vents to prevent from the American dogs’ scent.

At that time, Cu Chi Tunnels consisted of 3 floors of different depth. The top one was 3 meters under the grounds. The second one was 6 meters and the bottom was 12 meters under the ground. In heavily bombed areas, people spent much of their life underground, and the Cu Chi tunnels grew to house entire underground villages, in effect, with living quarters, kitchens, ordnance factories, hospitals and bomb shelters. In some areas there were even large theaters and music halls to provide diversion for the troops (many of them peasants) and their supporters.

Above the ground there were countless invisible booby traps awaiting American soldiers. Punji sticks, grenade traps, cartridge traps, snake pits, maces were cheap and relatively simple to make. These traps hampered operations, but also meant a psychological weapon as words about them spread. It’s estimated that approximately 11% of deaths and 15% of wounds to American soldiers were caused by booby traps and mines in the Vietnam War.

Cu Chi tunnels in wartime

During the Vietnam war, the United States relied heavily on aerial bombing, North Vietnamese and VC forces went underground to survive and continue their guerrilla tactics against the much better-supplied enemy. As a military headquarters for VC, Cu Chi Tunnels played a key role in the resistance to the American army in South Vietnam.

American attempts to flush out the Vietnamese tunnels proved ineffective. From 1961 to 1965, the Cu Chi tunnels was chosen to connecting all strategic points. On the ground, it’s a system of the barricade, minefields, nail pits, and spike-traps, which formed a solid and invincible battlefield.

To combat these guerrilla tactics, U.S. and South Vietnamese forces trained soldiers known as “tunnel rats”, armed only with a torch, a knife and a pistol, to navigate the tunnels in order to detect booby traps and enemy troop presence.

In January 1966, US and Australian forces tried to sweep the Cu Chi district in a large-scale attack dubbed Operation Crimp. The joint troops searched for enemy activity but failed after heavily bombing rain on the jungle region. The Communist forces disappeared into the underneath tunnels network. North Vietnamese and VC forces came back within months of the sweep.

At the event of Tet Offensive (1968), Cu Chi tunnels were the stronghold base to carry out the full-scale attack to Saigon. Despite suffering continuously severe carpet-bombing, the tunnels were rarely effectively destroyed. 

Cu Chi tunnels at present

In the years following the fall of Saigon in 1975, the Vietnamese government preserved the Cu Chi tunnels. Throughout the country's turbulent history, these iconic tunnels witnessed the sufferings in the fierce wars and symbolized the tenacity and resourcefulness of the Vietnamese people. 

In 2015, Cu Chi Tunnels were recognized as “Hero of Labour”, one of the noblest titles of the Socialist Republic of Vietnam. On 12th February 2016 Cu Chi Tunnels was officially designated the Special National Monument.