Overview
At the Treaty of Geneva in 1954, Indo-China was divided into Laos, Cambodia, North Vietnam and South Vietnam, although it was agreed to hold elections in 1956 to unify the two parts of Vietnam.
Ngo Dinh Diem, the ruler of South Vietnam, refused to hold elections.
Ho Chi Minh was a communist, who was supported by China. In 1960, he set up the National Liberation Front (NLF) in South Vietnam, which started a guerrilla war to take over South Vietnam from Diem and his American backers.
The Americans called the NLF guerrillas the Vietcong, and supported Diem with military advisers and money.
Diem's government was made up of rich Christian landowners. It was corrupt and unpopular and persecuted the poor Buddhist peasants. By 1963, most of South Vietnam's rural areas were under Vietcong control - the ARVN (South Vietnamese army) could not defeat them.
In 1963, the US supported a military coup, which murdered Diem and put a military government in South Vietnam.
In August 1964, sailors on the American warship USS Maddox in the Gulf of Tonkin claimed they had been attacked by North Vietnamese torpedo boats. The US Congress passed the Gulf of Tonkin resolution, allowing the American President Lyndon B. Johnson to take direct military action in retaliation.
In February 1965, the Vietcong attacked American air bases and killed American soldiers. President Johnson declared war against North Vietnam.
Why did the US get involved?
1. Containment
China had fallen to communism in 1949, and America had fought in Korea in 1950-53 to contain the spread of communism.
The US president, Lyndon B. Johnson, said: "I am not going to be the president who saw South-East Asia