The Vietnam War was a conflict that took place from 1955 to 1975, primarily between North Vietnam, supported by communist allies, and South Vietnam, backed by the United States and other anti-communist nations. The war aimed to prevent the spread of communism in Southeast Asia and resulted in significant military and civilian casualties. The conflict escalated in the 1960s, with the U.S. increasing its troop presence. Despite heavy involvement, the war ended with the fall of Saigon in 1975, leading to the reunification of Vietnam under communist control. The war had lasting effects on both Vietnam and the United States.