History of the United States (1964–1980)
The growing Watergate scandal was a major disaster for Nixon, eroding his political support in public opinion and in Washington. However he did manage to secure large-scale funding for South Vietnam, much of which was wasted. The United States withdrew its troops from Vietnam before the Paris Peace Accords in 1973. However, Watergate resulted in significant Democrat gains in the 1974 midterm elections and when the new 94th Congress convened the following January, it immediately voted to terminate all aid to South Vietnam in addition to passing a bill forbidding all further US military intervention in Southeast Asia. President Ford was against this, but as Congress had a veto-proof majority, he was forced to accept. South Vietnam rapidly collapsed as the North invaded it in force, and Saigon fell to the NVA on April 30, 1975. Later nearly one million Vietnamese managed to flee to the U.S. as refugees. The impact on the U.S. was muted, with few political recriminations, but it did leave a "Vietnam Syndrome" that cautioned against further military interventions anywhere else. Nixon (and his next two successors Ford and Carter) had dropped the containment policy and were not willing to intervene anywhere.
20th-century events
The second war, the Vietnam War, was perhaps the second most visible war of the 20th century, after World War II. After the French withdrawal from its former colony, on 21 July 1954, Vietnam became partitioned into two halves, much like Korea, along the 17th parallel. Fighting between North and South eventually escalated into a regional war.The United States provided aid to South Vietnam and contributed to propaganda efforts against the North, but was not directly involved until the Gulf of Tonkin Resolution, passed in reaction to a supposed North Vietnamese attack upon American destroyers, brought the U.S. into the war as a belligerent. The war was initially viewed as a fight to contain communism (see containment, Truman Doctrine, and Domino Theory), but, as more Americans were drafted and news of events such as the Tet Offensive and My Lai massacre leaked out, American sentiment turned against the war. U.S. President Richard Nixon was elected partially on claims of a "secret plan" to stop the war. This Nixon Doctrine involved a gradual pullout of American forces; South Vietnamese units were supposed to replace them, backed up by American air power. The plan went awry, with Nixon deliberately sabotaging peace talks for political gain, and the war spilled into neighboring Cambodia while South Vietnamese forces were pushed further back. Eventually, the U.S. and North Vietnam signed the Paris Peace Accords, ending U.S. involvement in the war. With the threat of U.S. retaliation gone, the North proceeded to violate the ceasefire and invaded the South with full military force. Saigon was captured on April 30, 1975, and Vietnam was unified under Communist rule a year later, effectively bringing an end to one of the most unpopular wars of all time.