The Indochina War was an almost thirty year war in Vietnam between 1946 and 1975, affecting the three Indochinese nations, namely Vietnam, Cambodia and Laos.

The Indochina War can be divided into the following phases:

1. French (First) Indochina War 1946-54
2. Vietnamese Civil War 1954-64
3. Vietnam (Second Indochina) War 1964-73
4. Fall of South Vietnam 1973-75

• For more information on the conflict from 1954 to 1975 see the article Vietnam War

In the French Indochina War, Vietnamese forces attempted to repel the French colonial regime from 1946 - 1954. The most spectacular battle would be that of Dien Bien Phu, where Vo Nguyen Giap defeated the French forces on May 7, 1954. The French were financially and logistically supported by the US during the later stages of the conflict. The French retreated in 1954.

In the second phase, which is the war between North and South Vietnam, US financial aid assisted South Vietnam. North Vietnam was communist, and many landlords fled to South Vietnam. The North Vietnamese wanted a united Vietnam under the Communist banner, but the US aided and backed South Vietnam and its president Ngo Dinh Diem. President Diem of South Vietnam was assassinated in 1963. Meanwhile, South Vietnamese communists, known as the Viet Cong (the North Vietnamese were the PAVN) were fighting the South Vietnamese ARVN (the South Vietnamese army in support of Diem).

The US troops fought by the side of the ARVN. The Viet Cong, which numbered only 60,000, held out against a combined army five times its strength that was unacquainted with guerilla warfare.

The Americans have also been criticised for the My Lai massacre, though the Vietnamese committed their fair share of atrocities as well. American death tolls ran as high as 273 per week at the height of the third phase of the Indochina War. Perhaps the most well-remembered incident would be the Tet Offensive. On the day of the Vietnamese New Year, the Têt, Viet Cong attacked 36 of 44 South Vietnam cities. Their main aim was to spark a national uprising for a united Vietnamese cause and to expel the Americans. They did not succeed in this aim, but they proved that they were capable of urban warfare as well. The Viet Cong suffered heavy casualties and were effectively wiped out.

By 1973, domestic pressure was heavy and the Americans withdrew their forces. Notable was Nixon's "Vietnamization", that is, handing the fighting over to the South Vietnamese ARVN while withdrawing US troops batch by batch. American withdrawal was almost complete by 1973.

With the departure of the Americans, South Vietnam swiftly fell under the Viet Cong and North Vietnam. Saigon was overrun by 1975 and Vietnam was finally united.