In 1955, a war broke out between Communist North Vietnam and the democratic government of South Vietnam. By 1965, the United States had officially joined the conflict as an ally to South Vietnam, joining the state in its fight against North Vietnam's effort to take control of the southern region of the country. The 20-year conflict came to an end shortly after the United States withdrew its forces, and American President Richard Nixon signed a ceasefire in 1973. Two years later, the country unified under Communist control. More than 58,000 Americans were killed during active duty.