The city of Hue, in northernmost South Vietnam, falls to the North Vietnamese. Hue was the most recent major city in South Vietnam to fall to the communists during their new offensive. The offensive had started in December 1974, when the North Vietnamese had launched a major attack against the lightly defended province of Phuoc Long, located north of Saigon along the Cambodian border. The communists overran the provincial capital of 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 North Vietnam committed a major violation of the Peace Accords. However, by the time the communists had taken Phuoc Long, Nixon had already resigned from office and his successor, Gerald Ford, was unable to convince a hostile Congress to make good on Nixon's promises to Saigon.
This situation emboldened the North Vietnamese, who launched a campaign in March 1975 to take the provincial capital of Ban Me Thuot in the Central Highlands. The South Vietnamese defenders there fought very poorly and were overwhelmed by the North Vietnamese attackers. Once again, the United States did nothing. President Thieu 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 and Hue fell. The communists then seized Da Nang, the second largest city in South Vietnam. Many South Vietnamese, both military and civilian, died in the general chaos while attempting to escape from the airport, docks, and beaches.
By this time, the South Vietnamese forces were in flight all over the northern half of South Vietnam. The North Vietnamese continued to attack south along the coast, overrunning city after city, methodically defeating the South Vietnamese forces. By April 27, the North Vietnamese had completely encircled Saigon and began to maneuver for their final assault, which became known as the "Ho Chi Minh Campaign." By the morning of April 30, it was all over. As the North Vietnamese tanks broke through the gates of the Presidential Palace in Saigon, the Vietnam War came to an end.