1975 spring offensive
The 1975 spring offensive, officially known as the general offensive and uprising of spring 1975, was the final North Vietnamese campaign of the Vietnam War that led to the capitulation of South Vietnam. In December 1974, People's Army of Vietnam's forces crossed from their bases in Cambodia and captured Phước Long Province by January 1975. After this success, the North Vietnamese leadership increased the scope of the PAVN offensive and attacked the Central Highlands from Cambodia in March, capturing the city of Buôn Ma Thuột on 18 March. These operations were intended to be preparatory to launching a general offensive in 1976.
Following these defeats, the South Vietnamese leadership realized they were no longer able to defend the entire country and ordered a strategic withdrawal from the Central Highlands. The retreat was a disaster as civilian refugees fled under fire alongside soldiers along a single highway to the coast. This situation was worsened by confusing orders, lack of command, and a well-led and aggressive enemy, which led to the destruction of most South Vietnamese forces in the Central Highlands. A similar collapse occurred in the northern provinces where PAVN forces captured both Huế and Đà Nẵng by the end of March.
Following the ARVN collapse, North Vietnam transferred its northern forces over south down the Ho Chi Minh trail through Laos and Cambodia to capture the South Vietnamese capital of Saigon and win the war in time to celebrate their late President Ho Chi Minh's birthday. South Vietnamese forces regrouped around the capital and defended the key transportation hubs at Phan Rang and Xuân Lộc, but the South Vietnamese had lost the political and military will to continue. On 21 April, South Vietnamese President Nguyễn Văn Thiệu resigned, hoping the North Vietnamese would reopen negotiations. However, the PAVN continued to attack. While IV Corps southwest of Saigon remained relatively stable, preventing VC units from capturing any provincial capitals, PAVN forces entered Saigon, forcing the South Vietnamese government, now under the leadership of Dương Văn Minh, to surrender on 30 April 1975.
Preliminaries
Strategies
The signing of the Paris Peace Accords in January 1973 did not end the fighting in South Vietnam since both sides violated the cease-fire and attempted to gain control of as much territory as possible. Occupation meant population control in any future negotiations or reunification effort. The fighting that erupted was not small in scale. The three-phase North Vietnamese "Land-grabbing-and population nibbling" campaign, for example, included four division-sized attacks to seize strategically advantageous positions. The International Commission of Control and Supervision, established by a protocol of the Paris agreement, had been assigned the task of monitoring the implementation of the cease-fire. The principles of consultation and unanimity among the members, however, doomed any effort to control the situation or to stop cease-fire violations, and the ICCS ceased to function in any meaningful way within a few months of its establishment.At the end of 1973, there was serious debate among the Hanoi leadership over future military policy as the Central Committee of the Communist Party of Vietnam convened to assess the progress of its efforts in the south. General Văn Tiến Dũng, PAVN chief of staff, and Defence Minister Võ Nguyên Giáp strongly urged the resumption of conventional military operations, warning that increasing passivity would affect the morale of the army. Premier Phạm Văn Đồng, however, feared resuming operations would drain vital resources needed for reconstruction in the north.
The final result of this debate was Resolution 21, which called for "strategic raids" on South Vietnamese forces in order to regain territory lost to the ARVN since the conclusion of the Peace Accords and to test the reaction of both the South Vietnamese military and the American government. The first blows of the new policy were delivered between March and November 1974, when the communists attacked ARVN forces in Quảng Đức Province and at Biên Hòa. Hanoi's leaders watched closely and anxiously as strikes by American B-52 Stratofortress bombers failed to materialize. During these operations, however, PAVN retook the military initiative, gaining experience in combined arms operations, depleting ARVN forces, causing them to expend large quantities of ammunition, and gaining avenues of approach and jump-off points for any new offensive.
South Vietnamese President Nguyễn Văn Thiệu had made his position on the cease-fire agreement quite public by proclaiming the "Four Nos": no negotiations with the communists; no communist political activities south of the Vietnamese Demilitarized Zone ; no coalition government; and no surrender of territory to the North Vietnamese or Provisional Revolutionary Government – policies which all but abrogated the Paris Accords. Thiệu still believed the promise made by President Richard Nixon to reintroduce American air power to the conflict if any serious violations of the agreement took place. It was also assumed that U.S. financial and military aid would continue to be forthcoming at previous levels.
On 1 July 1973, however, the U.S. Congress passed the Case–Church Amendment, legislation that all but prohibited any direct or indirect U.S. combat activities over or in Laos, Cambodia, and both Vietnams. On 7 November the legislative branch overrode Nixon's veto of the War Powers Act. During 1972–1973, South Vietnam had received $2.2 billion in U.S. assistance. In 1973–1974, that figure was slashed to $965 million, a more than 50 percent reduction. Nixon's growing political difficulties and the increasing antagonism between the legislative and executive branches over Vietnam policies, did little to dampen South Vietnamese expectations. Some among the Saigon leadership were more realistic in their appraisal. According to Republic of Vietnam Air Force General Dong Van Khuyen: "Our leaders continued to believe in U.S. air intervention even after the U.S. Congress had expressly forbidden it ... They deluded themselves." The shock of reduced aid was compounded on 9 August, when Richard Nixon, the guarantor of South Vietnamese independence, was forced to resign from office. In October 1973, the Arab oil embargo began, and the resulting oil shock of 1973–74 caused a massive bout of inflation that largely destroyed the South Vietnamese economy with a spokesman for Thiệu admitting in a TV interview that the government was being "overwhelmed" by the inflation. One consequence of the inflation was the South Vietnamese government had increasing difficulty in paying its soldiers.
Taking advantage of North Vietnam's period of recuperation in 1974, President Thiệu stretched his forces thin by launching offensives that retook most of the territory captured by PAVN forces during the land grab of 1973 and 15 percent of the total land area controlled by the PAVN at the time of the cease-fire. In April, Thiệu launched the Svay Rieng Campaign against PAVN strongholds in eastern Cambodia. This proved to be the last major offensive operation launched by the ARVN. While these operations succeeded, the cost in terms of manpower and resources was high. By the end of the year the military experienced shortages as a result of decreased American aid, while communist forces continued gaining strength.
By the end of October the North Vietnamese Politburo decided on its strategy for 1975 and 1976. In what became known as Resolution of 1975, the party leadership reported that the war reached its "final stage". The army was to consolidate its gains, eliminate South Vietnamese border outposts and secure its logistical corridor, and continue its force build-up in the south. During 1976 the final general offensive would begin. The following month, PAVN field commanders and their political officers were called to Hanoi to assess the new strategy. It was first decided that an attack in the Central Highlands would have the greatest chance of success, but this concept was challenged by Lieutenant General Trần Văn Trà, COSVN's military commander. His staff already drew a plan for a direct attack against Saigon, and Trà quickly proposed that his forces launch a probing attack in Phước Long Province to see how well the ARVN would fight and if the U.S. would react. Trà's plan offered the potential for great gain at low risk. First Party Secretary Lê Duẩn approved the plan, but warned Trà that failure would not be acceptable, telling him "Go ahead and attack... you must be sure of victory."
Opposing forces
ARVN
After the signing of the Paris Accords, the South Vietnamese government fielded the fourth largest military force in the world as a result of the American Enhance and Enhance Plus programs. The nation received new combat and transport aircraft, armored vehicles, helicopters, artillery pieces, and other equipment worth $753 million. The arms shipments were welcomed by Saigon, but the lack of sufficient training and dependence on the U.S. for spare parts, fuel, and ammunition caused maintenance and logistical problems. South Vietnamese forces certainly outnumbered combined PAVN/Viet Cong forces in the south with approximately one and one-half million troops in uniform. But almost 482,000 of this number belonged to either the Regional or Popular Forces, organizations of mixed reliability. Even the lesser number was misleading. Only about 200,000 of the remaining total served as regulars in the combat arms. The rest were in the administrative and logistical "tail" required to support them.The ARVN always had problems keeping men in the ranks, but during 1973–75, the problem reached epidemic proportions. During 1974, for example, only 65 percent of authorized manpower was present for duty at any time. The nation's officer corps still suffered from the promotion and retention of generals due to their political loyalties, not their professional abilities. Corruption and incompetence among officers was endemic, with some "raising it almost to an art form." In 1972, general Creighton Abrams fumed at ARVN complaints that they lacked arms and equipment. He said: “The ARVN haven’t lost their tanks because the enemy tanks knocked them out. The ARVN lost their tanks because goddamn it, they abandoned them. And, shit, if they had the Josef Stalin 3 , it wouldn’t have been any better.” He likewise harangued President Thieu and Saigon’s chief of staff Cao Van Vien: “Equipment is not what you need. You need men that will fight... You’ve got all the equipment you need... You lost most of your artillery because it was abandoned.”
Severe cutbacks in U.S. aid directly affected military performance. Artillery batteries previously allocated 100 rounds per day were reduced to firing only four daily. Each ARVN soldier was restricted to only 85 bullets per month. Because of fuel shortages and a lack of spare parts, sorties by South Vietnamese helicopter and cargo aircraft shrank by 50 to 70 percent. Due to President Thiệu's "no surrender of territory" command, the army was stretched to the limit defending terrain along a 600-mile frontier. Even the nation's strategic reserve, the Airborne and Marine Divisions, were occupied in static defensive roles. The ARVN, schooled by the Americans in rapid mobility and application of massive firepower, were losing the ability to deliver either. The military situation was exacerbated by the collapse of the South Vietnamese economy and a massive influx of refugees into the cities.
During the same period, the North Vietnamese were recovering from losses incurred during the Easter Offensive of 1972 by replacing personnel and modernizing their equipment with a new influx of Soviet and Chinese military aid. During 1973, North Vietnam received 2.8 million metric tons of goods from communist-bloc countries, a 50 percent increase over the previous year. In 1974 that total increased to 3.5 million metric tons , while the South's aid was slashed to only $965 million per year, down from $2.2 billion. As a result, while South Vietnam suffered a multitude of issues with replacing losses and/or bolstering their military strength, North Vietnam had little trouble doing both.