Armed conflict in Vietnam began in 1945, but the official starting point of the Vietnam War was the fraudulent election of Ngo Dinh Diem in 1955. The United States backed and advised Diem, who struggled to repress a Communist insurgency.
Once elected, Diem immediately began a large-scale purge of Communists in the country. The purge led to a division between Diem's South Vietnam and a strong insurgency in North Vietnam. A coup killed Diem in 1963, leading the United States to commit military forces to the country. The war formally ended when Communist forces captured Saigon in 1975. South Vietnamese President Duong Van Minh surrendered on April 30, 1975.