The Vietnam War, also known as the Second Indochina War, was in various ways a direct successor to the French Indochina War. The Vietnam War was an important war of the Cold War. It proved to be a battleground for Communism versus Capitalism.
In 1954, when the Viet Minh had defeated the French colonial army at the Battle of Dien Bien Phu, Vietnam was given independence from French rule. Due to the Geneva Conference, Vietnam was split into North and South Vietnam. North Vietnam was supposed to be ruled by Ho Chi Minh, whereas, South Vietnam was to be under the Emperor Bao Dai. In 1955, the South Vietnamese monarchy had been eradicated, and Ngo Dinh Diem became the president of the South Vietnamese republic. The Geneva Accords stated that elections would be held on June 1956, for the country's unification. However these elections were not held, and the US president also had no intentions of holding elections in Vietnam due to which the Communists would obviously emerge victorious, with North Vietnam not allowing free elections in their part of the country.
Therefore, as neither North or South Vietnam or the US had signed the election accord, it became probable that there would be a North and a South Vietnam