Declassified: Viet Cong

From hidden tunnel cities deep in the jungle, the Viet Cong launched operations that were terrifying in their ingenuity, savagery, and persistence. U.S. commanders made the mistake of fighting this battle as they had fought World War II. The North Vietnamese, employing a very different set of strategies, built a massive warren of tunnels and then faded into Laos when the battle turned against them.