April 23, 1975 - 100,000 NVA soldiers advance on Saigon which is now overflowing with refugees. On this same day, President Ford gives a speech at Tulane University stating the conflict in Vietnam is "a war that is finished as far as America is concerned."
April 27, 1975 - Saigon is encircled. 30,000 South Vietnamese soldiers are inside the city but are leaderless. NVA fire rockets into downtown civilian areas as the city erupts into chaos and widespread looting.
April 28, 1975 - 'Neutralist' General Duong Van "Big" Minh becomes the new president of South Vietnam and appeals for a cease-fire. His appeal is ignored.
April 29, 1975 - NVA shell Tan Son Nhut air base in Saigon, killing two U.S. Marines at the compound gate. Conditions then deteriorate as South Vietnamese civilians loot the air base. President Ford now orders Operation Frequent Wind, the helicopter evacuation of 7000 Americans and South Vietnamese from Saigon, which begins with the radio broadcast of the song "White Christmas" as a pre-arraigned code signal.
At Tan Son Nhut, frantic civilians begin swarming the helicopters. The evacuation is then shifted to the walled-in American embassy, which is secured by U.S. Marines in full combat gear. But the scene there also deteriorates, as thousands of civilians attempt to get into the compound.
Three U.S. aircraft carriers stand by off the coast of Vietnam to handle incoming Americans and South Vietnamese refugees. Many South Vietnamese pilots also land on the carriers, flying American-made helicopters which are then pushed overboard to make room for more arrivals. Filmed footage of the $250,000 choppers being tossed into the sea becomes an enduring image of the war's end.
April 30, 1975 - At 8:35 a.m., the last Americans, ten Marines from the embassy, depart Saigon, concluding the United States presence in Vietnam. North Vietnamese troops pour into Saigon and encounter little resistance. By 11 a.m., the red and blue Viet Cong flag flies from the presidential palace. President Minh broadcasts a message of unconditional surrender. The war is over.