The Vietnam War was a military conflict in present day Vietnam occurring from 1959 to April 30, 1975. The conflict was a successful effort by the Democratic Republic of Vietnam  and the indigenous National Front for the Liberation of South Vietnam, to impose on Vietnam a communist system, defeating the South Vietnamese Republic of Vietnam. To a degree, the Vietnam War was a "proxy war" between the U.S. and its Western allies on the side of the RVN, with the Soviet Union and the People's Republic of China supporting the DRV on the other. As a result of this it is often considered part of the Cold War.
The chief cause of the war was the failure of Vietnamese nationalists, in the form of the Viet Minh, to gain control of southern Vietnam both during and after their struggle for independence from France in the First Indochina War of 1946–54.
The U.S., in particular, deployed large numbers of military personnel to South Vietnam between 1954 and 1973. U.S. military advisors first became involved in Vietnam as early as 1950, when they began to assist French colonial forces. In 1956, these advisers assumed full responsibility for training the Army of the Republic of Vietnam or ARVN. President Kennedy increased America's troop number from 500 to 16,000. Large numbers of American combat troops began to arrive in 1965 and remained in South Vietnam until August 1972. Almost all of the remaining U.S. military personnel departed after the Paris Peace Agreement of 1973, leaving behind only an embassy guard. The last American troops left the country on April 30, 1975.
At various stages the conflict involved clashes between small units patrolling the mountains and jungles, guerrilla attacks in the villages and cities, and finally, large-scale conventional battles. U.S. aircraft also conducted substantial aerial bombing campaigns, targeting both logistical networks and the cities and transportation arteries of North Vietnam. Large quantities of chemical defoliants were also sprayed from the air in an effort to reduce the cover available to enemy combatants.
The Vietnam War was finally concluded on 30 April 1975, with the fall of the South Vietnamese capital of Saigon to North Vietnamese forces. The war claimed between 2 and 5.7 million Southeast Asian lives, a large number of whom were civilians.

The last official American military action in Southeast Asia occurred on 15 May 1975, when 18 Marines were killed during a rescue operation known as the Mayagüez incident.
The dire predictions of a generation did not come to fruition. The domino theory, so widely trumpeted, prove an illusion. South East Asia did not collaspe into the arms of communism. The idea of a monolithic communist block also prove misguided, as Nixon pried China away from it's traditional ally, the Soviet Union. Vietnam, without the presence of the United States, showed itself to be of little economic or stategic value. The American position in Asia remained unaltered by the loss. Far from undermining it's credibility abroad, in 1972 the United States signed a strategic arms limitation treaty with it's arch foe the Soviet Union. At home, a generation of Americans struggled to absorb the lessons of military intervension without clear motives or objectives. The war demontrated that no power, not even a superpower, has unlimited strength and resources. But perhaps most significantly, the Vietnam War illustrated that political will, as much as material might, is a decisive factor in determining the outcome of any conflict.

The U.S. deployed large numbers of military personnel to South Vietnam between 1954 and 1973. U.S. military advisors first became involved in Vietnam as early as 1950, when they began to assist French colonial forces. In 1956, these advisors assumed full responsibility for training the Army of the Republic of Vietnam or ARVN. President Kennedy increased America's troop number from 500 to 16,000. Large numbers of American combat troops began to arrive in 1965. The last American troops left the country on April 30, 1975. At various stages the conflict involved clashes between small units patrolling the mountains and jungles, guerrilla attacks in the villages and cities, and finally, large-scale conventional battles. U.S. aircraft also conducted substantial aerial bombing campaigns, targeting both logistical networks and the cities and transportation arteries of North Vietnam. Large quantities of chemical defoliants were also sprayed from the air in an effort to reduce the cover available to enemy combatants. The Vietnam War was finally concluded on 30 April 1975, with the fall of the South Vietnamese capital of Saigon to North Vietnamese forces. The war claimed between 2 and 5.7 million Southeast Asian lives, a large number of whom were civilians.