From the First Indo-China war, it was a long history. Back then in 1955, Vietnam involved in the Second Indo-China war that lasted almost 19 years. It is much towards the Communist alliances backed by the Russian in the north by the American and its alliances in the south. Vietnamese referred it as the war against the America. The tunnels were used by Viet Cong soldiers as hiding spots during combat, as well as serving as communication and supply routes, hospitals, food and weapon caches and living quarters for numerous North Vietnamese fighters. The tunnel systems were of great importance to the Viet Cong in their resistance to American forces, and helped to counter the growing American military effort. ~ Wikipedia