 The Tet Offensive ( Vietnamese : Sự kiện Tết Mậu Thân 1968 , or Tổng tiến công và nổi dậy Tết Mậu Thân ) was one of the largest military campaigns of the Vietnam War , launched on January 30 , 1968 , by forces of the Viet Cong and North Vietnamese People 's Army of Vietnam against the forces of the South Vietnamese Army of the Republic of Vietnam , the United States , and their allies . It was a campaign of surprise attacks against military and civilian commands and control centers throughout South Vietnam . The name of the offensive comes from the Tết holiday , the Vietnamese New Year , when the first major attacks took place . 
