1975 marked the end of the Vietnam War. The North Vietnamese People's Army of Vietnam (PAVN) launched the Spring Offensive in March; the South Vietnamese Army of the Republic of Vietnam (ARVN) was quickly defeated. The North Vietnamese captured Saigon on April 30, accepting the surrender of South Vietnam. In the final days of the war, the United States, which had supported South Vietnam for many years, carried out an emergency evacuation of its civilian and military personnel and more than 130,000 Vietnamese.
At the beginning of the Spring Offensive the balance of forces in Vietnam was approximately as follows; North Vietnam: 305,000 soldiers, 600 armored vehicles and 490 heavy artillery pieces in South Vietnam and South Vietnam: 1.0 million soldiers, 1,200 to 1,400 tanks and more than 1,000 pieces of heavy artillery.
The capital city of Cambodia, Phnom Penh, was captured by the Khmer Rouge on April 17. On December 2 the Pathet Lao took over the government of Laos, thus completing the communist conquest of the three Indochinese countries.
January 1 January In Cambodia, the Khmer Rouge attacked and drove back the government forces near Phnom Penh, the capital city. The Khmer Rouge now controlled 80 percent of the country and soon began attacking Phnom Penh, crowded with refugees, with rockets.
3 January The Jackson–Vanik amendment was signed into law in the U.S., its passage was a reason for increased Soviet military aid to North Vietnam as it abrogated secret Nixon administration trade commitments with the Soviet Union.
6 January Phước Bình, the capital of Phước Long Province, north of Saigon, was captured by the PAVN, becoming the first provincial capital controlled by the North Vietnamese. All but 850 of 5,400 South Vietnamese soldiers defending the province were killed or captured. The lack of a military response by the US to the loss of a province persuaded North Vietnam that it could take more aggressive actions.
8 January Delegates to a Politburo conference in North Vietnam agreed that the US was not going to intervene militarily in South Vietnam and therefore North Vietnam had the opportunity to "destroy and disintegrate" the South Vietnamese military.
11 January The United States Department of State protested that North Vietnam had violated the 1973 Paris Peace Accords by infiltrating 160,000 soldiers and 400 armored vehicles into South Vietnam. North Vietnam had improved the Ho Chi Minh trail, now a network of all-weather roads, through Cambodia and Laos and expanded their armament stockpiles.
21 January Asked at a press conference if there were circumstances under which the United States might again actively participate in the Vietnam War, U.S. President Gerald Ford said, "I cannot foresee any at the moment.""The President's News Conference", January 21, 1975, accessed 11 Sep 2017
26 January The last Mekong River supply convoy from South Vietnam arrived in Phnom Penh, five vessels had been destroyed by Khmer Rouge mines and ambushes. Henceforth, Phnom Penh was isolated from any outside assistance except by air, effectively surrounded by the Khmer Rouge.Daugherty, Leo (2011), The Vietnam War Day by Day, New York: Chartwell Books, p. 188
28 January Ford asked Congress for an additional $522 million in military aid to assist South Vietnam and Cambodia. Ford said that North Vietnam now had 289,000 troops in South Vietnam and large numbers of tanks, artillery and anti-aircraft weapons.
30 January South Vietnamese President Nguyễn Văn Thiệu declared the dissolution of the Hòa Hảo militia and over the following weeks there would be numerous clashes between the Hòa Hảo and ARVN forces in the Mekong Delta.
February 5 February PAVN General Văn Tiến Dũng arrived in South Vietnam to take command of PAVN/VC forces. He decided that capture of the city of Ban Mê Thuột, the capital of Đắk Lắk Province, would be his first objective.
25 February - 3 March A bipartisan Congressional delegation visited South Vietnam at the request of Ford. The delegation was led by John Flynt, a supporter of continued aid to South Vietnam and included Bella Abzug, Donald M. Fraser and Pete McCloskey, all opponents of continued aid. The delegation was unable to agree a unified position, other than their dislike of Ambassador Graham Martin.
March 4 March The PAVN began "Campaign 275" to capture the Central Highlands with diversionary attacks near Kon Tum and Pleiku while building up forces near Ban Me Thuot, the main objective of the campaign.
10 March The PAVN launched its attack on Ban Me Thuot, and by nightfall they held the center of the city although fighting continued in the outskirts.
12 March The ARVN II Corps commander, General Phạm Văn Phú, reported to his government that the PAVN were firmly in control of Ban Me Thuot.
Captured in the PAVN assault on Ban Me Thuot were 14 foreigners, including American missionaries with a six-year-old daughter and Paul Struharik, the provincial representative of the United States. The prisoners were taken to North Vietnam and held captive until being released on October 30.Andelman, David. A. "14 Captives Freed by Vietnam Reds" The New York Times, October 31, 1975
An Air Vietnam DC-4 crashed 25 km southwest of Pleiku while on a flight from Vientiane to Saigon killing all 26 on board, including New Zealand Red Cross team leader Malcolm Riding. The wreckage could not be inspected to determine the cause of the crash due to fighting in the area.
14 March Thiệu met with his military commanders and unrealistically ordered General Phú to retake Ban Me Thuot. All ARVN forces were to be withdrawn from other parts of the Central Highlands to be reassembled for the assault on Ban Me Thuot and for the defense of the coast. The withdrawal was to be carried out with secrecy. U.S. authorities and South Vietnamese provincial leaders were not informed of this decision. The provincial forces, mostly Montagnard highlanders, were to be abandoned.
15 March Phú abandoned efforts to retake Ban Me Thuot and began the retreat to the coast. The ARVN 23rd Division at Ban Me Thuot had been destroyed, with many desertions as South Vietnamese soldiers attempted to save themselves and their families, a pattern that would continue during the remainder of the war.
16 March The withdrawal of the ARVN from the Central Highlands, mostly the troops stationed in the cities of Pleiku and Kon Tum, began. The only route open to many was Route 7B, a highway in poor repair. As most senior ARVN officers had departed the highlands by helicopter, many of the remaining soldiers were a leaderless mob mixed with fleeing civilians. In the "convoy of tears", under fire by the PAVN, only about 60,000 of 180,000 fleeing civilians were known to have reached the coast and temporary safety. Only 900 of 7,000 South Vietnamese Rangers, who provided most of the defense of the convoy and 5,000 of 20,000 other South Vietnamese soldiers are known to have survived. Many of the soldiers probably deserted rather than report for duty.Editors of Boston Publishing Company (2014), The American Experience in Vietnam: Reflections on an Era, Boston: Zenith Press, p. 258
18-9 March The ARVN abandoned An Lộc with the 32nd Ranger Group withdrawing along Highway 13 to Chơn Thành Camp.
19 March Quảng Trị, the northernmost city of South Vietnam, was occupied by the PAVN without a fight, the defenders having been evacuated by sea.
24 March North Vietnam changed the name of Campaign 275 to the "Ho Chi Minh Campaign." The original plan of North Vietnam had been to gain control over the Central Highlands in 1975 and complete its conquest of the country in 1976. However, the rapid collapse of South Vietnamese defenses resulted in General Dung being given a more ambitious objective: the capture of Saigon before the birthday of Ho Chi Minh on May 19 and the onset of the rainy season at approximately the same date.
24 March - 1 April Two Regiments of the PAVN 9th Division supported by tanks attacked Chơn Thành Camp. The defenders destroyed seven T-54s with antitank rockets and recoilless rifle fire and, together with RVNAF airstrikes, they killed more than 100 PAVN soldiers. On 26 March, the 9th Division attacked again, apparently trying to retrieve disabled tanks, but was repulsed again. By 27 March the 273rd Regiment was sent to reinforce the 9th Division for another assault on the camp. After 2 attacks the PAVN had been repulsed for the loss of 240 killed and 11 tanks destroyed, while ARVN losses were 50 killed and wounded. At dawn on 31 March following a 3,000 round bombardment, the entire 9th Division, 273rd Regiment and the remaining tanks attacked Chơn Thành again. The PAVN penetrated the camp defenses three times and were repulsed each time. However resupply, reinforcement and medical evacuation from the camp was now impossible and the Ranger commander received permission to abandon Chơn Thành. On 1 April the RVNAF saturated the PAVN assembly areas and bivouacs with 52 sorties; under the cover of this attack, the Ranger and RF battalions began withdrawing separately to Bàu Bàng and Lai Khê, taking the remaining artillery and M41 tanks with them. One Ranger battalion and the RF battalion were ambushed and suffered moderate losses, but the 31st Ranger Group was now available to support South Vietnamese defenses elsewhere.
25 March After the fall of Quảng Trị, Hué, south, was the next major city to fall to the PAVN. The defenders were evacuated by sea. Both civilians and soldiers had begun abandoning the city several days earlier and headed south toward Da Nang, South Vietnam's second largest city.
28 March Ford authorized the use of U.S. navy vessels to assist in the evacuation of South Vietnamese cities.
The New Zealand surgical team is evacuated from Qui Nhơn ending a 12-year presence there.
29 March Da Nang, south of Hué, was the next city to fall to PAVN forces. Crowded with a half million refugees, 70,000 people had been evacuated by barge or air during the previous several days. ARVN soldiers forced themselves onto the evacuation planes and barges and comprised a large share of the evacuees, but the 16,000 soldiers evacuated were little more than 10 percent of the total ARVN force which had been stationed in I Corps. The former US naval and air base of Cam Ranh Bay, almost south, was the destination of most of the people evacuated.Isaacs, pp. 363–369; Thompson, Larry Clinton (2010), Refugee Workers in the Indochina Exodus, 1975–1982 Jefferson, North Carolina: MacFarland Publishing Company, p. 9
31 March U.S. Army Chief of Staff Frederick C. Weyand in South Vietnam assessed the situation. "It is possible that with abundant resupply and a great deal of luck, the GVN [Government of South Vietnam] could survive...It is extremely doubtful that it could withstand an offensive involving the commitment of three additional Communist divisions...without U.S. strategic air support." Colonel William Le Gro of the U.S. Embassy said that without U.S. strategic bombing of North Vietnamese forces, South Vietnam would be defeated within 90 days.
General Dung, was notified by his government that, due to the rapid collapse of South Vietnamese armed forces, he was to "liberate Saigon before the rainy season [mid-May]" The original plan had been to wait until 1976 before attacking Saigon and the southern one-half of South Vietnam.
Technicians from the United States Atomic Energy Commission escorted by Navy SEALS removed the fuel rods from the nuclear research reactor at Dalat University and flew them to Johnston Atoll.
April 1 April Qui Nhơn, South Vietnam's third largest city, south of Da Nang, was captured by the PAVN. More than one-half of the land area of South Vietnam was now under the control of the PAVN.