The Vietnam War was fought because South Vietnam intended to reclaim North Vietnam. At the end of World War II, the originally French-colonized Vietnam was split into two, and the southern part was given back to France.
The Vietnam War was seen as an outlet for Cold War efforts. North Vietnam was backed by Russia and China, who supplied weapons, while the South Vietnam force was backed by France and the United States. The war is now known for the heavy civilian and military losses that occurred and for the success of the North defending against the South. The South had a larger force that was aided by Americans, but the Northern guerrilla tactics were effective.