The Vietnam War or Second Indochina War was a war between the states oriented South Vietnam and the Soviet oriented North Vietnam. South Vietnam was supported by anti-communist allies, while North Vietnam was supported by communist allies. The conflict was in Vietnam, Laos, and Cambodia. The Vietnam War was a long, costly, and divisive conflict, intensified by the ongoing Cold War between the United States and the Soviet Union. More than 3 million people were killed during that war, which more than half of the dead were Vietnamese civilians.

The conflict emerged from the First Indochina War between the French and the communist Viet Minh. When the French left in 1954, the US assumed financial and military support for the South Vietnamese State. The Viet Cong (from Vietnamese ‘Viêt Công’), a South Vietnamese common front under the direction of North Vietnam, initiated guerrilla war in the south. Laos was also invaded by North Vietnam, establishing the Ho Chi Minh Trail to supply and reinforce the Viet Cong. Under President John F. Kennedy, US involvement escalated.

President Lyndon B. Johnson broad authority in 1964 to increase American military presence in Vietnam after an alleged conflict between North Vietnamese attack craft and a U.S. Destroyer. The deployment of combat troops increased troops levels to 184.000. Due to little progress, by the end of 1966, U.S. Secretary of Defense Robert McNamara began expressing doubts of victory. The U.S. and South Vietnam forces relied on air superiority and overwhelming firepower to conduct search and destroy operations. The US also conducted a large-scale strategic bombing campaign against North Vietnam and Laos, who were backed by the People’s Republic of China and the Soviet Union.

Due large-scale offensives throughout 1968, the Viet Cong sustained heavy losses. By the end of the year, the Viet Cong rebels held almost no territory in South Vietnam. A drastic reduction in guerrilla operations in 1969 was the result. North Vietnam declared a Provisional Revolutionary Government in South Vietnam opposing the government of the Republic of Vietnam. The wanted to give the reduced Viet Cong in South Vietnam a more international stature. The Viet Cong ware sidelined as the South Vietnam forces began more conventional combined warfare. By 1970, southern dominated Viet Cong units no longer existed, over 70% of communist troops in the south were northerners.

In the meantime, following the election of U.S. President Richard Nixon, a policy if ‘Vietnamization” began. U.S. forces sidelined and increasingly demoralized by domestic conflicts and reduced recruitments. The U.S. ground forces had largely withdrawn by 1972 and support was limited to air and artillery support, advisors, and materiel shipments. During the Easter Offensive of 1972, both sides suffered heavy casualties. North Vietnam failed to subdue South Vietnam, but South Vietnam itself failed to recapture all territory, leaving its military situation difficult. The Paris Peace Accords of 1973 saw all U.S. forces withdraw.

Despite the deployment of hundreds of thousands of troops, large-scale bombing, the use of chemical agents such as napalm and Agent Orange, the US was also forced by increasing criticism and massive protests in its own country. Opposition to the War bitterly divided Americans in the US. Even after President Richard Nixon ordered the withdrawal of the U.S. forces in 1973. Many perceived the war as a meaningless struggle. The Case-Church Amendment of 1973 officially ended direct U.S. military involvement.

When the US withdraw its troops and left Vietnam, the Peace accords were almost immediately broken. The long-backed government of South Vietnam was overthrown and united with North Vietnam. South Vietnam as seized by communist forces in 1975, and the country was unified as the Socialist Republic of Vietnam the following year. Within the US, the war gave a public aversion towards American overseas military involvements, which together with the Watergate scandal contributed to the crisis of confidence that affected the USA during the 1970s.