The North Vietnamese "Ho Chi Minh Campaign" begins. Despite the 1973 Paris Peace Accords cease fire, the fighting had continued between South Vietnamese forces and the North Vietnamese troops in South Vietnam. In December 1974, the North Vietnamese launched a major attack against the lightly defended province of Phuoc Long, located north of Saigon along the Cambodian border. They successfully overran the provincial capital at Phuoc Binh on January 6, 1975.
President Richard Nixon had repeatedly promised South Vietnamese President Nguyen Van Thieu that the United States would come to the aid of South Vietnam if the North Vietnamese committed a major violation of the Peace Accords. However, by the time the communists had taken Phuoc Long, Nixon had resigned from office and his successor, Gerald Ford, was unable to convince a hostile Congress to make good on Nixon's promises to Saigon.
The North Vietnamese, emboldened by the situation, launched Campaign 275 in March 1975 to take the provincial capital of Ban Me Thuot in the Central Highlands. The South Vietnamese defenders fought very poorly and were quickly overwhelmed by the North Vietnamese attackers. Once again, the United States did nothing. President Thieu, however, ordered his forces in the Highlands to withdraw to more defensible positions to the south. What started out as a reasonably orderly withdrawal degenerated into a panic that spread throughout the South Vietnamese armed forces. They abandoned Pleiku and Kontum in the Highlands with very little fighting and the North Vietnamese pressed the attack from the west and north. In quick succession, Quang Tri, Hue, and Da Nang in the north fell to the communist onslaught. The North Vietnamese continued to attack south along the coast, defeating the South Vietnamese forces one at a time.
As the North Vietnamese forces closed on the approaches to Saigon, the Politburo in Hanoi issued an order to Gen. Van Tien Dung to launch the "Ho Chi Minh Campaign," the final assault on Saigon itself. By April 27, the North Vietnamese had completely encircled Saigon and by April 30, the North Vietnamese tanks broke through the gates of the Presidential Palace in Saigon and the Vietnam War came to an end.