The Vietnam War lasted from 1954 to 1975 and involved military engagement between North Vietnam and South Vietnam, with the United States backing South Vietnam. France had previously controlled Vietnam but withdrew after their defeat at Dien Bien Phu in 1954. This led to Vietnam being divided along the 17th parallel, with communist North Vietnam controlling the north and US-backed South Vietnam controlling the south. Tensions rose and the US became increasingly involved, sending military advisors to support South Vietnam against North Vietnam and communist Viet Cong forces in the south. Major events of the war included the Gulf of Tonkin incident leading to increased US bombing of North Vietnam, the Tet Offensive of 1968, and the fall of Saigon in 1975 when North Vietnam defeated