In 1968, National Liberation Front guerrillas (Viet Cong) and North Vietnam Army troops launched a massive offensive against the cities and towns in South Vietnam. For three years the insurgents had been trying to wear down the South, but they now staked everything on a desperate all-out bid for victory. Although the Tet Offensive proved to be the beginning of the end for South Vietnam, it was the worst defeat suffered by the Communists in 30 years.