The Vietnam War honored all who served in Southeast Asia and remembered the more than 58,000 who paid the ultimate sacrifice in service to the country, as well as those who were left behind. It was a long, costly conflict between the communist regime of North Vietnam and its southern allies, known as the Viet Cong, and South Vietnam and its principal ally, the United States. The war began in 1954, though conflict in the region stretched back to the mid-1940's. More than 3 million people, including 58,000 Americans, were killed in the Vietnam War, and more than half were Vietnamese civilians. By 1969, at the peak of U.S. involvement, more than 500,000 U.S. military personnel were involved in the conflict. Growing opposition to the war in the United States led to bitter divisions among Americans before and after President Richard Nixon ordered the withdrawal of U.S. forces in 1973. In 1975, communist forces seized control of Saigon, ending the war, and the country was unified as the Socialist Republic of Vietnam the following year.