Vinh Moc tunnels ( Wikipedia ) is a tunnel complex in Quang Tri , Vietnam strategically located close to the old Demilitarised Zone ( DMZ ) and the 17 parallel which separated North Vietnam and South Vietnam. The tunnels were built to shelter the people from the intense bombing of Son Trung and Son Ha communes in Vinh Linh county of Quang Tri Province in the Vietnamese DMZ. The American Forces believed the villagers of Vinh Moc were supplying food and armaments to the North Vietnamese garrison on the island of Con Co which in turn was hindering the American bombers on their way to bomb Hanoi. The idea was to force the villagers of Vinh Moc to leave the area but as is typical in Vietnam there was nowhere else to go.
The villagers initially dug the tunnels to move their village 10 meters underground but the American Forces designed bombs that burrowed down 10 meters. Eventually against these odds, the villagers moved the village to a depth of 30 meters. It was constructed in several stages beginning in 1966 and used until early as 1972. The complex grew to include wells, kitchens, rooms for each family and spaces for healthcare. Around 60 families lived in the tunnels; As many as 17 children were born inside the tunnels.
The Vinh Moc tunnels were a success and no villagers lost their lives. The only direct hit was from a bomb that failed to explode; the resulting hole was later utilised as a ventilation shaft.
Three levels of tunnels were eventually built. Much of the sub-strata of Vietnam is limestone which is soft to dig through yet structurally sound. The limestone allowed easy hand digging of the tunnels and no structural supports were necessary.
When the war took place in Vinh Moc from 1966 - 1972, The American Forces released over 9,000 tons bombs in the area, with a ratio of 7 tons on an average of bombs per person. But the local people didn't want to lose their motherland, so they commenced digging the tunnels in 1965 and finished in 1967 with simple work tools in 18,000 labor days. The total length of the tunnels is nearly 2,000 meters long with 6 entrances to the top of the hills and 7 entrances to the South China Sea.