The Tet Offensive occurred in the Vietnam War in 1968. It was a major offensive launched by North Vietnamese and Viet Cong forces against South Vietnam and U.S. military bases during the Vietnamese lunar New Year (Tet). The surprise attacks expanded the scale and intensity of the war, with significant battles occurring in major cities, including Saigon and Hue. Although militarily a failure for North Vietnam, it was a psychological victory, as it challenged U.S. perceptions of progress in the war. The offensive shifted public opinion in the United States, leading to increased anti-war sentiment and questioning of U.S. involvement in Vietnam.