The Vietnam War lasted from 1954 to 1975 between North Vietnam and South Vietnam. The United States became involved to stop the spread of communism in Southeast Asia. Despite superior firepower, the U.S. was unable to defeat the Viet Cong guerilla forces hiding in the jungle. Direct U.S. military involvement ended in 1973 with a cease-fire agreement, but the war concluded in 1975 with a North Vietnamese victory. Over 55,000 American soldiers died during the conflict.