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.
South Vietnam
During the hours leading up to the surrender, the United States undertook a massive evacuation of its embassy in Saigon, Operation Frequent Wind. The evacuees included US government personnel as well as high-ranking members of the ARVN and other South Vietnamese who were seen as potential targets for persecution by the Communists. Many of the evacuees were taken directly by helicopter to multiple aircraft carriers waiting off the coast. An iconic image of the evacuation is the widely seen footage of empty Huey helicopters being jettisoned over the side of the carriers, to provide more room on the ship's deck for more evacuees to land. The evacuation was forced to stop by the US Navy. All the Marines and diplomats were evacuated, but thousands of South Vietnamese citizens waited in vain at the US embassy compound, and one block away at the former USAID and CIA office space in the Pittman Apartment House on 22 Gia Long Street atop the roof for helicopters that never came.