The Tet Offensive was a massive 1968 surprise attack launched by North Vietnam against the United States and South Vietnamese Army during the Vietnam War. The attack took place during Tet, one of the most sacred holidays in the Vietnamese calendar.

1. Date began: January 30, 1968
2. Casualties: 85,000 - 100,000 killed, wounded, or lost
3. Result: Took U.S. and South Vietnamese forces months to push offensive back
4. Came at time of growing U.S. public dissatisfaction with war

The Tet offensive is widely regarded by historians as the turning point in the Vietnam War. Prior to the event, U.S. forces had been aiding South Vietnamese troops in thwarting North Vietnamese attacks, and the American public largely believed that the North Vietnamese were incapable of a large-scale coordinated attack on the South. The North Vietnamese were perceived to be poorly equipped and undertrained, with little organized communication available to engage in anything more than uncoordinated guerrilla actions.

In January of 1968, both North Vietnam and South Vietnam announced a three-day ceasfire to celebrate the Tet holiday, a traditional observance of the solar new year. On January 31st, the North Vietnamese, and their South Vietnamese allies, the National Front for the Liberation of South Vietnam (NLF) began a wave of attacks throughout South Vietnam, attacking more than 100 towns and cities, including the national capital, Saigon. In military terms, the offensive was unsuccessful. The aggressors were roundly defeated in most of the areas where they attacked, and most of the fighting was over by June. Fighting was most fierce around the central Vietnamese city and religious center of Hue. In a psychological sense, the offensive was successful in achieving propaganda aims. Given that the American and South Vietnamese forces were largely unprepared for the attack, public perception of the event back home severely reduced the U.S. public's support for continued involvement in the conflict.