The Tet Offensive was a major escalation and one of the largest military campaigns of the Vietnam War. It was launched on January 30, 1968 by forces of the Viet Cong by the South-Vietnamese regime and the United States - and North Vietnamese People's Army of Vietnam against the forces of the South Vietnamese Army of the Republic of Vietnam, the United States Armed Forces and their allies. It was a campaign of surprise attacks against military and civilian command and control centers throughout South Vietnam. The name is the truncated version of the Lunar New Year festival name in Vietnamese, Tết Nguyên Đán, with the offense chosen during a holiday period as most ARVN personnel were on leave. The purpose of the wide-scale offensive by the Hanoi Politburo was to trigger political instability, in a belief that mass armed assault on urban centers would trigger defections and rebellions.
The offensive was launched prematurely in the late night hours of 30 January in the I and II Corps Tactical Zones of South Vietnam. This early attack allowed allied forces some time to prepare defensive measures.