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Vietnam War
Part of the Indochina Wars and the Cold War in Asia
Clockwise from top left: US Huey helicopters inserting South Vietnamese ARVN troops, 1970 North Vietnamese PAVN troops in action, c. 1966 US Marines using a flamethrower, 1967 South Vietnamese officer summarily executing a Viet Cong officer during the Tet Offensive, 1968 US Navy A-4 Skyhawk on a bombing run, 1966 Burial of civilians killed in the Massacre at Huế, 1968
Date 1 November 1955 – 30 April 1975 (19 years, 5 months and 29 days) Location South Vietnam North Vietnam Cambodia Laos South China Sea Gulf of Thailand (spillover conflict in China, and Thailand) Result North Vietnamese victory Territorial changes Reunification of North Vietnam and South Vietnam into the Socialist Republic of Vietnam in 1976
Belligerents
North Vietnam Viet Cong and PRG Pathet Lao Khmer Rouge GRUNK (1970–1975)  China (1965–1973)  Soviet Union  North Korea	South Vietnam United States  South Korea  Australia  New Zealand  Laos Cambodia (1967–1970) Khmer Republic (1970–1975)  Thailand  Philippines  Taiwan
Commanders and leaders
Hồ Chí Minh Tôn Đức Thắng Lê Duẩn Võ Nguyên Giáp Phạm Văn Đồng Trần Văn Trà ... and others	Ngô Đình Diệm X Nguyễn Văn Thiệu Nguyễn Cao Kỳ Dwight D. Eisenhower John F. Kennedy X Lyndon B. Johnson Richard Nixon Robert McNamara Melvin Laird William Westmoreland Creighton Abrams ... and others
Strength
≈860,000 (1967) North Vietnam: 690,000 (1966, including PAVN and Viet Cong) Viet Cong: ~200,000 (estimated, 1968) China: 170,000 (1968) 320,000 total Khmer Rouge: 70,000 (1972) Pathet Lao: 48,000 (1970) Soviet Union: ~3,000 North Korea: 200	≈1,420,000 (1968) South Vietnam: 850,000 (1968) 1,500,000 (1974–1975) United States: 2,709,918 serving in Vietnam total Peak: 543,000 (April 1969) Khmer Republic: 200,000 (1973) Laos: 72,000 (Royal Army and Hmong militia) South Korea: 48,000 per year (1965–1973, 320,000 total) Thailand: 32,000 per year (1965–1973) (in Vietnam and Laos) Australia: 50,190 total (Peak: 8,300 combat troops) New Zealand: Peak: 552 in 1968 Philippines: 2,061 Spain: 100–130 total (Peak: 30 medical troops and advisors)
Casualties and losses
North Vietnam & Viet Cong 30,000–182,000 civilian dead 849,018 military dead (per Vietnam; 1/3 non-combat deaths) 666,000–950,765 dead (US estimated 1964–1974) 232,000+ military missing (per Vietnam) 600,000+ military wounded Khmer Rouge: Unknown Pathet Lao: Unknown  China: ~1,100 dead and 4,200 wounded  Soviet Union: 16 dead  North Korea: 14 dead Total military dead/missing: ≈1,100,000 Total military wounded: ≈604,200 (excluding GRUNK/Khmer Rouge and Pathet Lao)	South Vietnam: 195,000–430,000 civilian dead Military dead: 313,000 (total) 254,256 combat deaths (between 1960 and 1974) 1,170,000 military wounded ≈ 1,000,000 captured  United States: 58,281 dead (47,434 from combat) 303,644 wounded (including 150,341 not requiring hospital care)  Laos: 15,000 army dead Khmer Republic: Unknown South Korea: 5,099 dead; 10,962 wounded; 4 missing  Australia: 521 dead; 3,129 wounded  Thailand: 351 dead  New Zealand: 37 dead  Taiwan: 25 dead 17 captured Philippines: 9 dead; 64 wounded Total military dead: 333,620 (1960–1974) – 392,364 (total) Total military wounded: ≈1,340,000+ (excluding FARK and FANK) Total military captured: est. 1,000,000+
Vietnamese civilian dead: 405,000–2,000,000 Vietnamese total dead: 966,000–3,010,000 Cambodian Civil War dead: 275,000–310,000 Laotian Civil War dead: 20,000–62,000 Non-Indochinese military dead: 65,494 Total dead: 1,326,494–3,447,494 For more information see Vietnam War casualties and Aircraft losses of the Vietnam War
FULRO fought an insurgency against both South Vietnam and North Vietnam with the Viet Cong and was supported by Cambodia for much of the war.

The Vietnam War (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam was supported by the Soviet Union and China, while South Vietnam was supported by the United States and other anti-communist nations. The conflict was the second of the Indochina Wars and a major proxy war of the Cold War between the Soviet Union and US. Direct US military involvement greatly escalated from 1965 until its withdrawal in 1973. The fighting spilled over into the Laotian and Cambodian Civil Wars, which ended with all three countries becoming communist in 1975.

After the defeat of French Indochina in the First Indochina War that began in 1946, Vietnam gained independence in the 1954 Geneva Conference but was divided into two parts at the 17th parallel: the Viet Minh, led by Ho Chi Minh, took control of North Vietnam, while the US assumed financial and military support for South Vietnam, led by Ngo Dinh Diem. The North Vietnamese began supplying and directing the Viet Cong (VC), a common front of dissidents in the south, which intensified a guerrilla war from 1957. In 1958, North Vietnam invaded Laos, establishing the Ho Chi Minh trail to supply and reinforce the VC. By 1963, the north had covertly sent 40,000 soldiers of its own People's Army of Vietnam (PAVN), armed with Soviet and Chinese weapons, to fight in the insurgency in the south. President John F. Kennedy increased US involvement from 900 military advisors in 1960 to 16,300 in 1963 and sent more aid to the Army of the Republic of Vietnam (ARVN), which failed to produce results. In 1963, Diem was killed in a US-backed military coup, which added to the south's instability.

Following the Gulf of Tonkin incident in 1964, the US Congress passed a resolution that gave President Lyndon B. Johnson authority to increase military presence without a declaration of war. Johnson launched a bombing campaign of the north and began sending combat troops, dramatically increasing deployment to 184,000 by the end of 1965, and to 536,000 by the end of 1968. US forces relied on air supremacy and overwhelming firepower to conduct search and destroy operations in rural areas. In 1968, North Vietnam launched the Tet Offensive, which was a tactical defeat but convinced many in the US that the war could not be won. The PAVN began engaging in more conventional warfare. Johnson's successor, Richard Nixon, began a policy of "Vietnamization" from 1969, which saw the conflict fought by an expanded ARVN, while US forces withdrew. A 1970 coup in Cambodia resulted in a PAVN invasion and a US–ARVN counter-invasion, escalating its civil war. US troops had mostly withdrawn from Vietnam by 1972, and the 1973 Paris Peace Accords saw the rest leave. The accords were broken almost immediately and fighting continued until the 1975 spring offensive and fall of Saigon to the PAVN, marking the war's end. North and South Vietnam were reunified in 1976.

The war exacted enormous human cost: estimates of Vietnamese soldiers and civilians killed range from 970,000 to 3 million. Some 275,000–310,000 Cambodians, 20,000–62,000 Laotians, and 58,220 US service members died. Its end would precipitate the Vietnamese boat people and the larger Indochina refugee crisis, which saw millions leave Indochina, an estimated 250,000 perished at sea. The US destroyed 20% of South Vietnam's jungle and 20–50% of the mangrove forests, by spraying over 20 million U.S. gallons (75 million liters) of toxic herbicides; a notable example of ecocide. The Khmer Rouge carried out the Cambodian genocide, while conflict between them and the unified Vietnam escalated into the Cambodian–Vietnamese War. In response, China invaded Vietnam, with border conflicts lasting until 1991. Within the US, the war gave rise to Vietnam syndrome, a public aversion to American overseas military involvement, which, with the Watergate scandal, contributed to the crisis of confidence that affected America throughout the 1970s.

Names

Various names have been applied and have shifted over time, though Vietnam War is the most commonly used title in English. It has been called the Second Indochina War since it spread to Laos and Cambodia, the Vietnam Conflict, and Nam (colloquially 'Nam). In Vietnam it is commonly known as Kháng chiến chống Mỹ (lit. 'Resistance War against America'). The Government of Vietnam officially refers to it as the Resistance War against America to Save the Nation. It is sometimes called the American War.

Background

Vietnam had been under French control as part of French Indochina since the mid-19th century. Under French rule, Vietnamese nationalism was suppressed, so revolutionary groups conducted their activities abroad, particularly in France and China. One such nationalist, Nguyen Sinh Cung, established the Indochinese Communist Party in 1930, a Marxist–Leninist political organization which operated primarily in Hong Kong and the Soviet Union. The party aimed to overthrow French rule and establish an independent communist state in Vietnam.

Japanese occupation of Indochina

In September 1940, Japan invaded French Indochina, following France's capitulation to Nazi Germany. French influence was suppressed by the Japanese, and in 1941 Cung, now known as Ho Chi Minh, returned to Vietnam to establish the Viet Minh, an anti-Japanese resistance movement that advocated for independence. The Viet Minh received aid from the Allies, namely the US, Soviet Union, and Republic of China. Beginning in 1944, the US Office of Strategic Services (O.S.S.) provided the Viet Minh with weapons, ammunition, and training to fight the occupying Japanese and Vichy French forces. Atrocities committed by the Japanese against the Vietnamese people led many to join the resistance, and by the end of 1944 the Viet Minh had grown to over 500,000 members. US President Franklin D. Roosevelt continued to support Vietnamese resistance throughout the war, and proposed that Vietnam's independence be granted under an international trusteeship after the war was over.

In March 1945, Japan, losing the war, overthrew the French government in Indochina, establishing the Empire of Vietnam and installing Vietnamese Emperor Bảo Đại as its figurehead leader. Following the surrender of Japan in August, the Viet Minh launched the August Revolution, overthrowing the Japanese-backed state and seizing weapons from the surrendering Japanese forces. On 2 September, Ho Chi Minh proclaimed the Declaration of independence of the Democratic Republic of Vietnam (DRV). However, on 23 September, French forces overthrew the DRV and reinstated French rule. American support for the Viet Minh promptly ended, and O.S.S. forces left as the French sought to reassert control of the country.

First Indochina War

Tensions between the Viet Minh and French authorities had erupted into full-scale war by 1946, a conflict which soon became entwined with the wider Cold War. On 12 March 1947, US president Harry S. Truman announced the Truman Doctrine, an anticommunist foreign policy which pledged US support to nations resisting "attempted subjugation by armed minorities or by outside pressures". In Indochina, this doctrine was first put into practice in February 1950, when the United States recognized the French-backed State of Vietnam in Saigon, led by former Emperor Bảo Đại, as the legitimate government of Vietnam, after the communist states of the Soviet Union and People's Republic of China recognized the Democratic Republic of Vietnam, led by Ho Chi Minh, as the legitimate Vietnamese government the previous month. The outbreak of the Korean War in June convinced Washington policymakers that the war in Indochina was another example of communist expansionism, directed by the Soviet Union.

Military advisors from China began assisting the Viet Minh in July 1950. Chinese weapons, expertise, and laborers transformed the Viet Minh from a guerrilla force into a regular army. In September 1950, the US further enforced the Truman Doctrine by creating a Military Assistance and Advisory Group (MAAG) to screen French requests for aid, advise on strategy, and train Vietnamese soldiers. By 1954, the US had spent $1 billion in support of the French military effort, shouldering 80% of the cost of the war.

Battle of Dien Bien Phu

During the Battle of Dien Bien Phu in 1954, US carriers sailed to the Gulf of Tonkin and the US conducted reconnaissance flights. France and the US discussed the use of tactical nuclear weapons, though reports of how seriously this was considered and by whom, are vague. According to then-Vice President Richard Nixon, the Joint Chiefs of Staff drew up plans to use nuclear weapons to support the French. Nixon, a so-called "hawk", suggested the US might have to "put American boys in". President Dwight D. Eisenhower made American participation contingent on British support, but the British were opposed. Eisenhower, wary of involving the US in an Asian land war, decided against intervention. Throughout the conflict, US intelligence estimates remained skeptical of France's chance of success.

On 7 May 1954, the French garrison at Dien Bien Phu surrendered. The defeat marked the end of French military involvement in Indochina. At the Geneva Conference, they negotiated a ceasefire with the Viet Minh, and independence was granted to Cambodia, Laos, and Vietnam.

Transition period

At the 1954 Geneva Conference, Vietnam was temporarily partitioned at the 17th parallel. Ho Chi Minh wished to continue war in the south, but was restrained by Chinese allies who convinced him he could win control by electoral means. Under the Geneva Accords, civilians were allowed to move freely between the two provisional states for a 300-day period. Elections throughout the country were to be held in 1956 to establish a unified government. However, the US, represented at the conference by Secretary of State John Foster Dulles, objected to the resolution; Dulles' objection was supported only by the representative of Bảo Đại. John Foster's brother, Allen Dulles, who was director of the Central Intelligence Agency, then initiated a psychological warfare campaign which exaggerated anti-Catholic sentiment among the Viet Minh and distributed propaganda attributed to Viet Minh threatening an American attack on Hanoi with atomic bombs.

During the 300-day period, up to one million northerners, mainly minority Catholics, moved south, fearing persecution by the Communists. The exodus was coordinated by a U.S.-funded $93 million relocation program, which involved the French Navy and the US Seventh Fleet to ferry refugees. The northern refugees gave the later Ngô Đình Diệm regime a strong anti-communist constituency. Over 100,000 Viet Minh fighters went to the north for "regroupment", expecting to return south within two years. The Viet Minh left roughly 5,000 to 10,000 cadres in the south as a base for future insurgency. The last French soldiers left South Vietnam in April 1956 and the PRC also completed its withdrawal from North Vietnam.

Between 1953 and 1956, the North Vietnamese government instituted agrarian reforms, including "rent reduction" and "land reform", which resulted in political oppression. During land reform, North Vietnamese witnesses suggested a ratio of one execution for every 160 village residents, which extrapolates to 100,000 executions. Because the campaign was mainly in the Red River Delta area, 50,000 executions became accepted by scholars. However, declassified documents from Vietnamese and Hungarian archives indicate executions were much lower, though likely greater than 13,500. In 1956, leaders in Hanoi admitted to "excesses" in implementing this program and restored much of the land to the original owners.

The south, meanwhile, constituted the State of Vietnam, with Bảo Đại as Emperor, and Ngô Đình Diệm as prime minister. Neither the US, nor Diệm's State of Vietnam, signed anything at the Geneva Conference. The non-communist Vietnamese delegation objected strenuously to any division of Vietnam, but lost when the French accepted the proposal of Viet Minh delegate Phạm Văn Đồng, who proposed Vietnam eventually be united by elections under the supervision of "local commissions". The US countered with what became known as the "American Plan", with the support of South Vietnam and the UK. It provided for unification elections under the supervision of the UN, but was rejected by the Soviet delegation. The US said, "With respect to the statement made by the representative of the State of Vietnam, the United States reiterates its traditional position that peoples are entitled to determine their own future and that it will not join in any arrangement which would hinder this". US President Eisenhower wrote in 1954:

I have never talked or corresponded with a person knowledgeable in Indochinese affairs who did not agree that had elections been held as of the time of the fighting, possibly 80% of the population would have voted for the Communist Ho Chi Minh as their leader rather than Chief of State Bảo Đại. Indeed, the lack of leadership and drive on the part of Bảo Đại was a factor in the feeling prevalent among Vietnamese that they had nothing to fight for.

According to the Pentagon Papers, which commented on Eisenhower's observation, Diệm would have been a more popular candidate than Bảo Đại against Hồ, stating that "It is almost certain that by 1956 the proportion which might have voted for Ho - in a free election against Diem - would have been much smaller than 80%." In 1957, independent observers from India, Poland, and Canada representing the International Control Commission (ICC) stated that fair elections were impossible, with the ICC reporting that neither South nor North Vietnam had honored the armistice agreement.

From April to June 1955, Diệm eliminated political opposition in the south by launching operations against religious groups: the Cao Đài and Hòa Hảo of Ba Cụt. The campaign also attacked the Bình Xuyên organized crime group, which was allied with members of the communist party secret police and had military elements. The group was defeated in April following a battle in Saigon. As broad-based opposition to his harsh tactics mounted, Diệm increasingly sought to blame the communists.

In a referendum on the future of the State of Vietnam in October 1955, Diệm rigged the poll supervised by his brother Ngô Đình Nhu and was credited with 98% of the vote, including 133% in Saigon. His American advisors had recommended a more "modest" winning margin of "60 to 70 percent." Diệm, however, viewed the election as a test of authority. He declared South Vietnam to be an independent state under the name Republic of Vietnam (ROV), with him as president. Likewise, Ho Chi Minh and other communists won at least 99% of the vote in North Vietnamese "elections".

The domino theory, which argued that if a country fell to communism, all surrounding countries would follow, was first proposed by the Eisenhower administration. John F. Kennedy, then a senator, said in a speech to the American Friends of Vietnam: "Burma, Thailand, India, Japan, the Philippines and obviously Laos and Cambodia are among those whose security would be threatened if the Red Tide of Communism overflowed into Vietnam."

Diệm era, 1954–1963

Rule

A devout Catholic, Diệm was fervently anti-communist, nationalist, and socially conservative. Historian Luu Doan Huynh notes "Diệm represented narrow and extremist nationalism coupled with autocracy and nepotism." Most Vietnamese were Buddhist, and alarmed by Diệm's actions, like his dedication of the country to the Virgin Mary.

In the summer of 1955, Diệm launched the "Denounce the Communists" campaign, during which suspected communists and other anti-government elements were arrested, imprisoned, tortured, or executed. He instituted the death penalty in August 1956 against activity deemed communist. The North Vietnamese government claimed that, by November 1957, over 65,000 individuals were imprisoned and 2,148 killed in the process. According to Gabriel Kolko, 40,000 political prisoners had been jailed by the end of 1958. In October 1956, Diệm launched a land reform program limiting the size of rice farms per owner. 1.8m acres of farm land became available for purchase by landless people. By 1960, the process had stalled because many of Diem's biggest supporters were large landowners.

In May 1957, Diệm undertook a 10-day state visit to the US. President Eisenhower pledged his continued support, and a parade was held in Diệm's honor. But Secretary of State Dulles privately conceded Diệm had to be backed because they could find no better alternative.

Insurgency in the South, 1954–1960

Between 1954 and 1957, the Diệm government succeeded in preventing large-scale organized unrest in the countryside. In April 1957, insurgents launched an assassination campaign, referred to as "extermination of traitors". 17 people were killed in the Châu Đốc massacre at a bar in July, and in September a district chief was killed with his family. By early 1959, Diệm had come to regard the violence as an organized campaign and implemented Law 10/59, which made political violence punishable by death and property confiscation. There had been division among former Viet Minh, whose main goal was to hold elections promised in the Geneva Accords, leading to "wildcat" activities separate from the other communists and anti-GVN activists. Douglas Pike estimated that insurgents carried out 2,000 abductions, and 1,700 assassinations of government officials, village chiefs, hospital workers and teachers from 1957 to 1960. Violence between insurgents and government forces increased drastically from 180 clashes in January 1960, to 545 clashes in September.

In September 1960, COSVN, North Vietnam's southern headquarters, ordered a coordinated uprising in South Vietnam against the government and a third of the population was soon living in areas of communist control. In December 1960, North Vietnam formally created the Viet Cong (VC) with the intent of uniting all anti-GVN insurgents, including non-communists. It was formed in Memot, Cambodia, and directed through COSVN. The VC "placed heavy emphasis on the withdrawal of American advisors and influence, on land reform and liberalization of the GVN, on coalition government and the neutralization of Vietnam." The identities of the leaders of the organization were often kept secret.

Support for the VC was driven by resentment of Diem's reversal of Viet Minh land reforms in the countryside. The Viet Minh had confiscated large private landholdings, reduced rents and debts, and leased communal lands, mostly to poorer peasants. Diem brought the landlords back, people who had been farming land for years had to return it to landlords and pay years of back rent. Marilyn B. Young wrote that "The divisions within villages reproduced those that had existed against the French: 75% support for the NLF, 20% trying to remain neutral and 5% firmly pro-government".

North Vietnamese involvement

In March 1956, southern communist leader Lê Duẩn presented a plan to revive the insurgency entitled "The Road to the South" to the Politburo in Hanoi. However, as China and the Soviets opposed confrontation, his plan was rejected. Despite this, the North Vietnamese leadership approved tentative measures to revive southern insurgency in December 1956. Communist forces were under a single command structure set up in 1958. In May 1958, North Vietnamese forces seized the transportation hub at Tchepone in Southern Laos near the demilitarized zone, between North and South Vietnam.

The North Vietnamese Communist Party approved a "people's war" on the South at a session in January 1959, and, in May, Group 559 was established to maintain and upgrade the Ho Chi Minh trail, at this time a six-month mountain trek through Laos. On 28 July, North Vietnamese and Pathet Lao forces invaded Laos, fighting the Royal Lao Army all along the border. About 500 of the "regroupees" of 1954 were sent south on the trail during its first year of operation. The first arms delivery via the trail was completed in August 1959. In April 1960, North Vietnam imposed universal military conscription for men. About 40,000 communist soldiers infiltrated the south from 1961 to 1963.

Kennedy's escalation, 1961–1963

In the 1960 U.S. presidential election, Senator John F. Kennedy defeated incumbent Vice President Richard Nixon. Although Eisenhower warned Kennedy about Laos and Vietnam, Europe and Latin America "loomed larger than Asia on his sights." In June 1961, he bitterly disagreed with Soviet premier Nikita Khrushchev when they met in Vienna to discuss key U.S.–Soviet issues. Only 16 months later, the Cuban Missile Crisis (October 1962) played out on television worldwide. It was the closest the Cold War came to nuclear war.

The Kennedy administration remained committed to the Cold War foreign policy inherited from the Truman and Eisenhower administrations. In 1961, the US had 50,000 troops based in South Korea, and Kennedy faced four crisis situations: the failure of the Bay of Pigs Invasion he had approved in April, settlement negotiations between the pro-Western government of Laos and the Pathet Lao communist movement in May, construction of the Berlin Wall in August, and the Cuban Missile Crisis in October. Kennedy believed another failure to stop communist expansion would irreparably damage US credibility. He was determined to "draw a line in the sand" and prevent a communist victory in Vietnam. He told James Reston of The New York Times after the Vienna summit with Khrushchev, "Now we have a problem making our power credible and Vietnam looks like the place."

Kennedy's policy toward South Vietnam assumed Diệm and his forces had to defeat the guerrillas on their own. He was against the deployment of American combat troops and observed "to introduce U.S. forces in large numbers there today, while it might have an initially favorable military impact, would almost certainly lead to adverse political and, in the long run, adverse military consequences." The quality of the South Vietnamese military, however, remained poor. Poor leadership, corruption, and political promotions weakened the ARVN. The frequency of guerrilla attacks rose as the insurgency gathered steam. While Hanoi's support for the VC played a role, South Vietnamese governmental incompetence was at the core of the crisis.

One major issue Kennedy raised was whether the Soviet space and missile programs had surpassed those of the US. Although Kennedy stressed long-range missile parity with the Soviets, he was interested in using special forces for counterinsurgency warfare in Third World countries threatened by communist insurgencies. Although they were intended for use behind front lines after a conventional Soviet invasion of Europe, Kennedy believed guerrilla tactics employed by special forces, such as the Green Berets, would be effective in a "brush fire" war in Vietnam.

Kennedy advisors Maxwell Taylor and Walt Rostow recommended US troops be sent to South Vietnam disguised as flood relief workers. Kennedy rejected the idea but increased military assistance. In April 1962, John Kenneth Galbraith warned Kennedy of the "danger we shall replace the French as a colonial force in the area and bleed as the French did." Eisenhower put 900 advisors in Vietnam, and by November 1963, Kennedy had put 16,000 military personnel there.

The Strategic Hamlet Program was initiated in late 1961. This joint U.S.–South Vietnamese program attempted to resettle the rural population into fortified villages. It was implemented in early 1962 and involved some forced relocation and segregation of rural South Vietnamese, into new communities where the peasantry would be isolated from the VC. It was hoped these new communities would provide security for the peasants and strengthen the tie between them and the central government. However, by November 1963 the program had waned, and it ended in 1964. In July 1962, 14 nations, including China, South Vietnam, the Soviet Union, North Vietnam, and the US, signed an agreement promising to respect Laos' neutrality.

Ousting and assassination of Ngô Đình Diệm

The inept performance of the ARVN was exemplified by failed actions such as the Battle of Ấp Bắc on 2 January 1963, in which the VC won a battle against a much larger and better-equipped South Vietnamese force, many of whose officers seemed reluctant even to engage in combat. The ARVN lost 83 soldiers and 5 US helicopters, serving to ferry troops shot down by VC forces, while the VC lost only 18 soldiers. The ARVN forces were led by Diệm's most trusted general, Huỳnh Văn Cao. Cao was a Catholic, promoted due to religion and fidelity rather than skill, and his main job was to preserve his forces to stave off coups. Policymakers in Washington began to conclude Diệm was incapable of defeating the communists and might even make a deal with Ho Chi Minh. He seemed concerned only with fending off coups and had become paranoid after attempts in 1960 and 1962, which he partly attributed to US encouragement. As Robert F. Kennedy noted, "Diệm wouldn't make even the slightest concessions. He was difficult to reason with ..." Historian James Gibson summed up the situation:

Strategic hamlets had failed ... The South Vietnamese regime was incapable of winning the peasantry because of its class base among landlords. Indeed, there was no longer a 'regime' in the sense of a relatively stable political alliance and functioning bureaucracy. Instead, civil government and military operations had virtually ceased. The National Liberation Front had made great progress and was close to declaring provisional revolutionary governments in large areas.

Discontent with Diệm's policies exploded in May 1963, following the Huế Phật Đản shootings of nine Buddhists protesting the ban on displaying the Buddhist flag on Vesak, Buddha's birthday. This resulted in mass protests -the Buddhist crisis- against discriminatory policies that gave privileges to Catholics over the Buddhist majority. Diệm's elder brother Ngô Đình Thục was the Archbishop of Huế and aggressively blurred the separation between church and state. Thuc's anniversary celebrations occurred shortly before Vesak had been bankrolled by the government, and Vatican flags were displayed prominently. There had been reports of Catholic paramilitaries demolishing Buddhist pagodas throughout Diệm's rule. Diệm refused to make concessions to the Buddhist majority or take responsibility for the deaths. On 21 August 1963, the ARVN Special Forces of Colonel Lê Quang Tung, loyal to Diệm's younger brother Ngô Đình Nhu, raided pagodas, causing widespread destruction and leaving a death toll into the hundreds.

US officials began discussing regime change during the middle of 1963. The United States Department of State wanted to encourage a coup, while the Pentagon favored Diệm. Chief among the proposed changes was removal of Diệm's younger brother Nhu, who controlled the secret police and special forces, and was seen as being behind the Buddhist repression and the architect of the Ngô family's rule. This proposal was conveyed to the US embassy in Saigon in Cable 243. The CIA contacted generals planning to remove Diệm, and told them the US would not oppose such a move, nor punish them by cutting off aid. Diệm was overthrown and then executed, along with his brother, on 2 November 1963. When Kennedy was informed, Maxwell Taylor remembered he "rushed from the room with a look of shock and dismay on his face." Kennedy had not anticipated Diệm's murder. The U.S. ambassador Henry Cabot Lodge, invited the coup leaders to the embassy and congratulated them. Lodge informed Kennedy that "the prospects now are for a shorter war". Kennedy wrote Lodge a letter congratulating him for "a fine job".

Following the coup, chaos ensued. Hanoi took advantage and increased its support for the VC. South Vietnam entered extreme political instability, as one military government toppled another in quick succession. Increasingly, each new regime was viewed by the communists as a puppet of the Americans; whatever the failings of Diệm, his credentials as a nationalist had been impeccable. US advisors were embedded at every level of the South Vietnamese armed forces. They were however criticized for ignoring the political nature of the insurgency. The Kennedy administration sought to refocus US efforts on pacification – which in this case was defined as countering the growing threat of insurgency – and "winning the hearts and minds" of the population. Military leadership in Washington, however, was hostile to any role for U.S. advisors other than troop training. General Paul Harkins, the commander of U.S. forces in South Vietnam, confidently predicted victory by Christmas 1963. The CIA was less optimistic, however, warning that "the Viet Cong by and large retain de facto control of much of the countryside and have steadily increased the overall intensity of the effort".

Paramilitary officers from the CIA's Special Activities Division trained and led Hmong tribesmen in Laos and into Vietnam. The indigenous forces were in the tens of thousands and conducted direct action missions, led by paramilitary officers, against the Communist Pathet Lao forces and their North Vietnamese supporters. The CIA ran the Phoenix Program and participated in the Military Assistance Command, Vietnam – Studies and Observations Group (MAC-V SOG).

Gulf of Tonkin and Johnson's escalation, 1963–1969

Kennedy was assassinated on 22 November 1963. Vice President Lyndon B. Johnson had not been heavily involved with policy toward Vietnam; however, upon becoming president, he immediately focused it. On 24 November 1963, he said, "the battle against communism ... must be joined ... with strength and determination." Johnson knew he had inherited a deteriorating situation in South Vietnam, but adhered to the widely accepted domino argument for defending the South: Should they retreat or appease, either action would imperil other nations. Findings from RAND's Viet Cong Motivation and Morale Project bolstered his confidence that an air war would weaken the insurgency. Some argue the policy of North Vietnam was not to topple other non-communist governments in South East Asia.

The military revolutionary council, meeting in lieu of a strong South Vietnamese leader, had 12 members. It was headed by General Dương Văn Minh, whom journalist Stanley Karnow, recalled as "a model of lethargy". Lodge cabled home about Minh: "Will he be strong enough to get on top of things?" Minh's regime was overthrown in January 1964 by General Nguyễn Khánh. There was persistent instability in the military: several coups—not all successful—occurred in a short period of time.

Gulf of Tonkin incident

On 2 August 1964, USS Maddox, on an intelligence mission along North Vietnam's coast, fired upon and damaged torpedo boats approaching it in the Gulf of Tonkin. A second attack was reported two days later on USS Turner Joy and Maddox. The circumstances were murky. Johnson commented to Undersecretary of State George Ball that "those sailors out there may have been shooting at flying fish." An NSA publication declassified in 2005 revealed there was no attack on 4 August.

The second "attack" led to retaliatory airstrikes, and prompted Congress to approve the Gulf of Tonkin Resolution on 7 August 1964. The resolution granted the president power "to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression" and Johnson relied on this as giving him authority to expand the war. Johnson pledged he was not "committing American boys to fighting a war that I think ought to be fought by the boys of Asia to help protect their own land".

The National Security Council recommended a three-stage escalation of the bombing of North Vietnam. Following an attack on a U.S. Army base on 7 February 1965, airstrikes were initiated, while Soviet Premier Alexei Kosygin was on a state visit to North Vietnam. Operation Rolling Thunder and Operation Arc Light expanded aerial bombardment and ground support operations. The bombing campaign, which lasted three years, was intended to force North Vietnam to cease its support for the VC by threatening to destroy North Vietnamese air defenses and infrastructure. It was additionally aimed at bolstering South Vietnamese morale. Between March 1965 and November 1968, Rolling Thunder deluged the north with a million tons of missiles, rockets and bombs.

Bombing of Laos

Bombing was not restricted to North Vietnam. Other aerial campaigns, targeted different parts of the VC and PAVN infrastructure. These included the Ho Chi Minh Trail through Laos and Cambodia. The ostensibly neutral Laos had become the scene of a civil war, pitting the Laotian government backed by the US, against the Pathet Lao and its North Vietnamese allies.

Massive aerial bombardment against the Pathet Lao and PAVN forces was carried out by the US to prevent the collapse of the Royal central government, and deny use of the Ho Chi Minh Trail. Between 1964 and 1973, the U.S. dropped two million tons of bombs on Laos, nearly equal to the 2.1 million tons of bombs it dropped on Europe and Asia during World War II, making Laos the most heavily bombed country in history, relative to its population.

The objective of stopping North Vietnam and the VC was never reached. The Chief of Staff of the United States Air Force Curtis LeMay, however, had long advocated saturation bombing in Vietnam and wrote of the communists that "we're going to bomb them back into the Stone Age".

The 1964 offensive

Following the Gulf of Tonkin Resolution, Hanoi anticipated the arrival of US troops and began expanding the VC, as well as sending increasing numbers of PAVN personnel southwards. They were outfitting the VC forces and standardizing their equipment with AK-47 rifles and other supplies, as well as forming the 9th Division. "From a strength of approximately 5,000 at the start of 1959 the Viet Cong's ranks grew to about 100,000 at the end of 1964 ... Between 1961 and 1964 the Army's strength rose from about 850,000 to nearly a million men." U.S. troop numbers deployed to Vietnam during the same period were much lower: 2,000 in 1961, rising to 16,500 in 1964. The use of captured equipment decreased, while greater numbers of ammunition and supplies were required to maintain regular units. Group 559 was tasked with expanding the Ho Chi Minh Trail, in light of the bombardment by US warplanes. The war had shifted into the final, conventional phase of Hanoi's three-stage protracted warfare model. The VC was now tasked with destroying the ARVN and capturing and holding areas; however, it was not yet strong enough to assault major towns and cities.

In December 1964, ARVN forces suffered heavy losses at the Battle of Bình Giã, in a battle both sides viewed as a watershed. Previously, the VC had utilized hit-and-run guerrilla tactics. At Binh Gia, however, they defeated a strong ARVN force in a conventional battle and remained in the field for four days. Tellingly, South Vietnamese forces were again defeated in June 1965 at the Battle of Đồng Xoài.

American ground war

On 8 March 1965, 3,500 U.S. Marines were landed near Da Nang, South Vietnam. This marked the beginning of the American ground war. U.S. public opinion overwhelmingly supported the deployment. The Marines' initial assignment was defense of Da Nang Air Base. The first deployment was increased to nearly 200,000 by December. U.S. military had long been schooled in offensive warfare. Regardless of political policies, U.S. commanders were institutionally and psychologically unsuited to a defensive mission.

General William Westmoreland informed Admiral U. S. Grant Sharp Jr., commander of U.S. Pacific forces, that the situation was critical, "I am convinced that U.S. troops with their energy, mobility, and firepower can successfully take the fight to the NLF (Viet Cong)". With this recommendation, Westmoreland was advocating an aggressive departure from America's defensive posture and the sidelining of the South Vietnamese. By ignoring ARVN units, the U.S. commitment became open-ended. Westmoreland outlined a three-point plan to win the war:

• Phase 1. Commitment of U.S. and allied forces necessary to halt the losing trend by the end of 1965.
• Phase 2. U.S. and allied forces mount major offensive actions to seize the initiative to destroy guerrilla and organized enemy forces. This phase would end when the enemy had been worn down and driven back from major populated areas.
• Phase 3. If the enemy persisted, a period of 12–18 months following Phase 2 would be required for final destruction of enemy forces remaining in remote base areas.

The plan was approved by Johnson and marked a profound departure from the insistence that South Vietnam was responsible for defeating the VC. Westmoreland predicted victory by the end of 1967. Johnson did not communicate this change in strategy to the media. Instead he emphasized continuity. The change in policy depended on matching the North Vietnamese and VC in a contest of attrition and morale. The opponents were locked in a cycle of escalation. Westmoreland and McNamara touted the body count system for gauging victory, a metric that would prove flawed.

The American buildup transformed the South Vietnamese economy and had a profound effect on society. South Vietnam was inundated with manufactured goods. Washington encouraged its SEATO allies to contribute troops; Australia, New Zealand, Thailand and the Philippines agreed to do so. South Korea would ask to join the Many Flags program in return for economic compensation. Major allies, however, notably NATO countries Canada and the UK, declined troop requests.

The U.S. and its allies mounted complex search and destroy operations. In November 1965, the U.S. engaged in its first major battle with the PAVN, the Battle of Ia Drang. The operation was the first large scale helicopter air assault by the U.S., and first to employ Boeing B-52 Stratofortress strategic bombers in support. These tactics continued in 1966–67, however, the PAVN/VC insurgents remained elusive and demonstrated tactical flexibility. By 1967, the war had generated large-scale internal refugees, 2 million in South Vietnam, with 125,000 people evacuated and rendered homeless during Operation Masher alone, which was the largest search and destroy operation to that point. Operation Masher would have negligible impact, however, as the PAVN/VC returned to the province just four months after it ended. Despite major operations, which the VC and PAVN would typically evade, the war was characterized by smaller-unit contacts or engagements. The VC and PAVN would initiate 90% of large firefights, and thus the PAVN/VC would retain strategic initiative despite overwhelming US force and fire-power deployment. The PAVN and Viet Cong had developed strategies capable of countering US military doctrines and tactics: see NLF and PAVN battle tactics.

Meanwhile, the political situation in South Vietnam began to stabilize with the arrival of prime minister Air Marshal Nguyễn Cao Kỳ and figurehead chief of state, General Nguyễn Văn Thiệu, in mid-1965 at the head of a junta. In 1967, Thieu became president with Ky as his deputy, after rigged elections. Although they were nominally a civilian government, Kỳ was supposed to maintain real power through a behind-the-scenes military body. However, Thiệu outmanoeuvred and sidelined Kỳ. Thiệu was accused of murdering Kỳ loyalists through contrived military accidents. Thiệu remained president until 1975, having won a one-candidate election in 1971.

Johnson employed a "policy of minimum candor" with the media. Military information officers sought to manage coverage by emphasizing stories that portrayed progress. This policy damaged the public trust in official pronouncements. As coverage of the war and the Pentagon diverged, a so-called credibility gap developed. Despite Johnson and Westmoreland publicly proclaiming victory and Westmoreland stating the "end is coming into view", internal reports in the Pentagon Papers indicate that VC forces retained strategic initiative and controlled their losses. VC attacks against static US positions accounted for 30% of engagements, VC/PAVN ambushes and encirclements for 23%, American ambushes against VC/PAVN forces for 9%, and American forces attacking Viet Cong emplacements only 5%.

Tet Offensive and its aftermath

In late 1967, the PAVN lured American forces into the hinterlands at Đắk Tô and at the Marine Khe Sanh combat base, where the U.S. fought The Hill Fights. These were part of a diversionary strategy meant to draw US forces towards the Central Highlands. Preparations were underway for the Tet Offensive, with the intention of Văn Tiến Dũng forces to launch "direct attacks on the American and puppet nerve centers—Saigon, Huế, Danang, all the cities, towns and main bases ..." Le Duan sought to placate critics of the stalemate by planning a decisive victory. He reasoned this could be achieved through sparking an uprising within the towns and cities, along with mass defections among ARVN units, who were on leave during the truce period.

The Tet Offensive began on 30 January 1968, as over 100 cities were attacked by over 85,000 VC/PAVN troops, including assaults on military installations, headquarters, and government buildings, including the U.S. Embassy in Saigon. U.S. and South Vietnamese forces were shocked by the scale, intensity and deliberative planning, as infiltration of personnel and weapons into the cities was accomplished covertly; the offensive constituted an intelligence failure on the scale of Pearl Harbor. Most cities were recaptured within weeks, except the former imperial capital Huế, which PAVN/VC troops held on for 26 days. They executed approximately 2,800 unarmed Huế civilians and foreigners they considered to be spies. In the following Battle of Huế American forces employed massive firepower that left 80% of the city in ruins. At Quảng Trị City, the ARVN Airborne Division, the 1st Division and a regiment of the US 1st Cavalry Division managed to hold out and overcome an assault intended to capture the city. In Saigon, VC/PAVN fighters had captured areas in and around the city, attacking key installations before US and ARVN forces dislodged them after three weeks. During one battle, Peter Arnett reported an infantry commander saying of the Battle of Bến Tre that "it became necessary to destroy the village in order to save it."

During the first month of the offensive, 1,100 Americans and other allied troops, 2,100 ARVN and 14,000 civilians were killed. After two months, nearly 5,000 ARVN and over 4,000 U.S. forces had been killed and 45,820 wounded. The U.S. claimed 17,000 PAVN/VC had been killed and 15,000 wounded. A month later a second offensive known as the May Offensive was launched; it demonstrated the VC were still capable of carrying out orchestrated nationwide offensives. Two months later a third offensive was launched, Phase III Offensive. PAVN records of their losses across all three offensives was 45,267 killed and 111,179 total casualties. It had become the bloodiest year up to then. The failure to spark a general uprising and lack of defections among the ARVN units meant both war goals of Hanoi had fallen flat at enormous cost.

Prior to Tet, in November 1967, Westmoreland had spearheaded a public relations drive for the Johnson administration to bolster flagging public support. In a speech to the National Press Club he said a point had been reached "where the end comes into view." Thus, the public was shocked and confused when Westmoreland's predictions were trumped by the Tet Offensive. Public approval of his performance dropped from 48% to 36%, and endorsement for the war fell from 40% to 26%." The public and media began to turn against Johnson as the offensives contradicted claims of progress.

At one point in 1968, Westmoreland considered the use of nuclear weapons in a contingency plan codenamed Fracture Jaw, which was abandoned when it became known to the White House. Westmoreland requested 200,000 additional troops, which was leaked to the media, and the fallout combined with intelligence failures caused him to be removed from command in March 1968, succeeded by his deputy Creighton Abrams.

On 10 May 1968, peace talks began between the US and North Vietnam in Paris. Negotiations stagnated for five months, until Johnson gave orders to halt the bombing of North Vietnam. Hanoi realized it could not achieve a "total victory" and employed a strategy known as "talking while fighting, fighting while talking", in which offensives would occur concurrently with negotiations.

Johnson declined to run for re-election as his approval rating slumped from 48% to 36%. His escalation of the war divided Americans, cost 30,000 American lives by that point and was regarded to have destroyed his presidency. Refusal to send more troops was seen as Johnson's admission that the war was lost. As McNamara said, "the dangerous illusion of victory by the United States was therefore dead."

Vietnam was a major political issue during the United States presidential election in 1968. The election was won by Republican Richard Nixon who claimed to have a secret plan to end the war.

Vietnamization (1969–1972)

Nuclear threats and diplomacy

Nixon began troop withdrawals in 1969. His plan to build up the ARVN so it could take over the defense of South Vietnam became known as "Vietnamization". As the PAVN/VC recovered from their 1968 losses and avoided contact, Abrams conducted operations aimed at disrupting logistics, with better use of firepower and more cooperation with the ARVN. In October 1969, Nixon had ordered B-52s loaded with nuclear weapons to race to the border of Soviet airspace to convince the Soviet Union, in accord with the madman theory, he was capable of anything to end the Vietnam War. Nixon had sought détente with the Soviet Union and rapprochement with China, which decreased tensions and led to nuclear arms reductions. However, the Soviets continued to supply the North Vietnamese.

Hanoi's war strategy

On 2 September 1969, Ho Chi Minh died aged 79. The failure of the 1968 Tet Offensive to spark a popular uprising in the south caused a shift in Hanoi's war strategy, and the Giáp-Chinh "Northern-First" faction regained control over military affairs from the Lê Duẩn-Hoàng Văn Thái "Southern-First" faction. An unconventional victory was sidelined in favor of a conventional victory through conquest. Large-scale offensives were rolled back in favor of small-unit and sapper attacks as well as targeting the pacification and Vietnamization strategy. Following Tet, the PAVN had transformed from a light-infantry, limited mobility force into a high-mobile and mechanized combined arms force. By 1970, over 70% of communist troops in the south were northerners, and southern-dominated VC units no longer existed.

U.S. domestic controversies

The anti-war movement was gaining strength in the US. Nixon appealed to the "silent majority" who he said supported the war without showing it. But revelations of the 1968 My Lai Massacre, in which a US Army unit raped and killed civilians, and the 1969 "Green Beret Affair", where eight Special Forces soldiers, were arrested for the murder of a suspected double agent, provoked national and international outrage.

In 1971, the Pentagon Papers were leaked to The New York Times. The top-secret history of US involvement in Vietnam, commissioned by the Department of Defense, detailed public deceptions on the part of the government. The Supreme Court ruled its publication was legal.

Collapsing U.S. morale

Following the Tet Offensive and decreasing support among the US public, US forces began a period of morale collapse, and disobedience. At home, desertion rates quadrupled from 1966 levels. Among the enlisted, only 2.5% chose infantry combat positions in 1969–70. ROTC enrollment decreased from 191,749 in 1966 to 72,459 by 1971, and reached a low of 33,220 in 1974, depriving US forces of much-needed military leadership.

Open refusal to engage in patrols or carry out orders emerged, with a notable case of an entire company refusing orders to carry out operations. Unit cohesion began to dissipate and focused on minimizing contact with the PAVN/VC. A practice known as "sand-bagging" started, where units ordered to patrol would go into the country-side, find a site out of view from superiors and radio in false coordinates and unit reports. Drug usage increased among US forces, 30% regularly used marijuana, while a House subcommittee found 10% regularly used high-grade heroin. From 1969 on, search-and-destroy operations became referred to as "search and avoid" operations, falsifying battle reports while avoiding guerrillas. 900 fragging and suspected fragging incidents were investigated, most occurring between 1969 and 1971. In 1969, field-performance was characterized by lowered morale, lack of motivation, and poor leadership. The significant decline in US morale was demonstrated by the Battle of FSB Mary Ann in March 1971, in which a sapper attack inflicted serious losses on the U.S. defenders. Westmoreland, no longer in command but tasked with investigation of the failure, cited a dereliction of duty, lax defensive postures and lack of officers in charge.

On the collapse of morale, historian Shelby Stanton wrote:

In the last years of the Army's retreat, its remaining forces were relegated to static security. The American Army's decline was readily apparent in this final stage. Racial incidents, drug abuse, combat disobedience, and crime reflected growing idleness, resentment, and frustration ... the fatal handicaps of faulty campaign strategy, incomplete wartime preparation, and the tardy, superficial attempts at Vietnamization. An entire American army was sacrificed on the battlefield of Vietnam.

ARVN taking the lead and U.S. ground force withdrawal

Beginning in 1969, American troops were withdrawn from border areas where most of the fighting took place and redeployed along the coast and interior. US casualties in 1970 were less than half of 1969, after being relegated to less active combat. While US forces were redeployed, the ARVN took over combat operations, with casualties double US casualties in 1969, and more than triple US ones in 1970. In the post-Tet environment, membership in the South Vietnamese Regional Force and Popular Force militias grew, and they were now more capable of providing village security, which the Americans had not accomplished.

In 1970, Nixon announced the withdrawal of an additional 150,000 American troops, reducing US numbers to 265,500. By 1970, VC forces were no longer southern-majority, nearly 70% of units were northerners. Between 1969 and 1971 the VC and some PAVN units had reverted to small unit tactics typical of 1967 and prior, instead of nationwide offensives. In 1971, Australia and New Zealand withdrew their soldiers and US troops were further reduced to 196,700, with a deadline to remove another 45,000 troops by February 1972. The US reduced support troops, and in March 1971 the 5th Special Forces Group, the first American unit deployed to South Vietnam, withdrew.

Cambodia

Prince Norodom Sihanouk had proclaimed Cambodia neutral since 1955, but permitted the PAVN/VC to use the port of Sihanoukville and the Sihanouk Trail. In March 1969 Nixon launched a secret bombing campaign, called Operation Menu, against communist sanctuaries along the Cambodia/Vietnam border. Only five high-ranking congressional officials were informed.

In March 1970, Sihanouk was deposed by his pro-American prime minister Lon Nol, who demanded North Vietnamese troops leave Cambodia or face military action. Nol began rounding up Vietnamese civilians in Cambodia into internment camps and massacring them, provoking reactions from the North and South Vietnamese governments. In April–May 1970, North Vietnam invaded Cambodia at the request of the Khmer Rouge, following negotiations with deputy leader Nuon Chea. Nguyen Co Thach recalls: "Nuon Chea has asked for help and we have liberated five provinces of Cambodia in ten days." US and ARVN forces launched the Cambodian Campaign in May to attack PAVN/VC bases. A counter-offensive in 1971, as part of Operation Chenla II by the PAVN, would recapture most of the border areas and decimate most of Nol's forces.

The US incursion into Cambodia sparked nationwide U.S. protests as Nixon had promised to deescalate American involvement. Four students were killed by National Guardsmen in May 1970 during a protest at Kent State University, which provoked further public outrage. The reaction by the administration was seen as callous, reinvigorating the declining anti-war movement. The US Air Force continued to bomb Cambodia in support of the Cambodian government as part of Operation Freedom Deal.

Laos

Building on the success of ARVN units in Cambodia, and further testing the Vietnamization program, the ARVN were tasked with Operation Lam Son 719 in February 1971, the first major ground operation to attack the Ho Chi Minh Trail, at the crossroad of Tchepone. This offensive was the first time the PAVN would field-test its combined arms force. The first few days were a success, but momentum slowed after fierce resistance. Thiệu had halted the general advance, leaving PAVN armored divisions able to surround them.

Thieu ordered air assault troops to capture Tchepone and withdraw, despite facing four-times larger numbers. During the withdrawal, the PAVN counterattack had forced a panicked rout. Half of the ARVN troops were either captured or killed, half of the ARVN/US support helicopters were downed and the operation was considered a fiasco, demonstrating operational deficiencies within the ARVN. Nixon and Thieu had sought to use to showcase victory simply by capturing Tchepone, and it was spun off as an "operational success".

Easter Offensive and Paris Peace Accords (1972)

Vietnamization was again tested by the Easter Offensive of 1972, a conventional PAVN invasion of South Vietnam. The PAVN overran the northern provinces and attacked from Cambodia, threatening to cut the country in half. US troop withdrawals continued, but American airpower responded, beginning Operation Linebacker, and the offensive was halted. The US Navy also initiated Operation Pocket Money in May, an aerial mining campaign in Haiphong Harbor that prevented North Vietnam's allies from resupplying it with weapons and aid by sea.

The war was central to the 1972 U.S. presidential election as Nixon's opponent, George McGovern, campaigned on immediate withdrawal. Nixon's Security Advisor, Henry Kissinger, had continued secret negotiations with North Vietnam's Lê Đức Thọ and in October 1972 reached an agreement. Thiệu demanded changes to the peace accord upon its discovery, and when North Vietnam went public with the details, the Nixon administration claimed they were attempting to embarrass the president. The negotiations became deadlocked when Hanoi demanded changes. To show his support for South Vietnam and force Hanoi back to the negotiating table, Nixon ordered Operation Linebacker II, a bombing of Hanoi and Haiphong in December 1972. Nixon pressured Thiệu to accept the agreement or face military action.

On 15 January 1973, all US combat activities were suspended. Lê Đức Thọ and Henry Kissinger, along with the PRG Foreign Minister Nguyễn Thị Bình and a reluctant Thiệu, signed the Paris Peace Accords on 27 January 1973. This ended direct U.S. involvement in the Vietnam War, created a ceasefire between North Vietnam/PRG and South Vietnam, guaranteed the territorial integrity of Vietnam under the Geneva Conference of 1954, called for elections or a political settlement between the PRG and South Vietnam, allowed 200,000 communist troops to remain in the south, and agreed to a POW exchange. There was a 60-day period for the withdrawal of US forces. "This article", noted Peter Church, "proved ... to be the only one of the Paris Agreements which was fully carried out." All US forces personnel were withdrawn by March 1973.

U.S. exit and final campaigns (1973–1975)

In the lead-up to the ceasefire on 28 January, both sides attempted to maximize land and population under their control in a campaign known as the War of the flags. Fighting continued after the ceasefire, without US participation, and throughout the year. North Vietnam was allowed to continue supplying troops in the South but only to replace expended material. The Nobel Peace Prize was awarded to Kissinger and Thọ, but Thọ declined it saying true peace did not yet exist.

On 15 March 1973, Nixon implied the US would intervene militarily if the North launched a full offensive, and Secretary of Defense Schlesinger re-affirmed this during his June confirmation hearings. Public and congressional reaction to Nixon's statement was unfavorable, prompting the Senate to pass the Case–Church Amendment to prohibit any intervention.

Northern leaders expected the ceasefire terms would favor their side, but Saigon, bolstered by a surge of US aid just before the ceasefire went into effect, began to roll them back. The North responded with a new strategy hammered out in meetings in Hanoi in March 1973, according to the memoirs of Trần Văn Trà. With US bombings suspended, work on the Ho Chi Minh Trail and other logistical structures could proceed. Logistics would be upgraded until the North was in a position to launch a massive invasion of the South, projected for the 1975–76 dry season. Trà calculated this date would be Hanoi's last opportunity to strike, before Saigon's army could be fully trained. The PAVN resumed offensive operations when the dry season began in 1973, and by January 1974 had recaptured territory it lost during the previous dry season.

Within South Vietnam, the departure of the US and the global recession after the 1973 oil crisis hurt an economy partly dependent on US financial support and troop presence. After clashes that left 55 ARVN soldiers dead, Thiệu announced on 4 January 1974, that the war had restarted and the Peace Accords were no longer in effect. There were over 25,000 South Vietnamese casualties during the ceasefire period. Gerald Ford took over as US president in August 1974, and Congress cut financial aid to South Vietnam from $1 billion a year to $700 million. Congress voted in restrictions on funding to be phased in through 1975 and then total cutoff in 1976.

The success of the 1973–1974 dry season offensive inspired Trà to return to Hanoi in October 1974 and plead for a larger offensive the next dry season. This time, Trà could travel on a drivable highway with fueling stops, a vast change from when the Ho Chi Minh Trail was a dangerous mountain trek. Giáp, the North Vietnamese defense minister, was reluctant to approve Trà's plan since a larger offensive might provoke US reaction and interfere with the big push planned for 1976. Trà appealed to Giáp's superior, Lê Duẩn, who approved it. Trà's plan called for a limited offensive from Cambodia into Phước Long Province. The strike was designed to solve logistical problems, gauge the reaction of South Vietnamese forces, and determine whether the US would return. On 13 December 1974, PAVN forces attacked Phước Long. Phuoc Binh fell on 6 January 1975. Ford desperately asked Congress for funds to assist and re-supply the South before it was overrun. Congress refused. The fall of Phuoc Binh and lack of American response left the South Vietnamese elite demoralized.

The speed of this success led the Politburo to reassess its strategy. It decided operations in the Central Highlands would be turned over to General Văn Tiến Dũng and that Pleiku should be seized, if possible. Dũng said to Lê Duẩn: "Never have we had military and political conditions so perfect or a strategic advantage as great as we have now." At the start of 1975, the South Vietnamese had three times as much artillery and twice as many tanks and armored vehicles as the PAVN. However, heightened oil prices meant many assets could not be leveraged. Moreover, the rushed nature of Vietnamization, intended to cover the US retreat, resulted in a lack of spare parts, ground-crew, and maintenance personnel, which rendered most of it inoperable.

Campaign 275

On 10 March 1975, Dũng launched Campaign 275, a limited offensive into the Central Highlands, supported by tanks and heavy artillery. The target was Ban Ma Thuột; if the town could be taken, the provincial capital Pleiku and the road to the coast, would be exposed for a campaign in 1976. The ARVN proved incapable of resisting the onslaught, and its forces collapsed. Again, Hanoi was surprised by the speed of their success. Dung urged the Politburo to allow him to seize Pleiku immediately and turn his attention to Kon Tum. He argued that with two months of good weather until onset of the monsoon, it would be irresponsible not to take advantage.

Thiệu, a former general, ordered the abandonment of the Central Highlands and less defensible positions in a rushed policy described as "light at the top, heavy at the bottom". While the bulk of ARVN forces attempted to flee, isolated units fought desperately. ARVN general Phu abandoned Pleiku and Kon Tum and retreated toward the coast, in what became known as the "convoy of tears". On 20 March, Thiệu reversed himself and ordered Huế, Vietnam's third-largest city, be held at all costs, and then changed policy several times. As the PAVN launched their attack, panic set in, and ARVN resistance withered. On 22 March, the PAVN attacked Huế. Civilians flooded the airport and docks hoping for escape. As resistance in Huế collapsed, PAVN rockets rained down on Da Nang and its airport. By 28 March 35,000 PAVN troops were poised to attack the suburbs. By 30 March 100,000 leaderless ARVN troops surrendered as the PAVN marched through Da Nang. With the fall of the city, the defense of the Central Highlands and Northern provinces ended.

Final North Vietnamese offensive

With the north half of the country under their control, the Politburo ordered Dũng to launch the final offensive against Saigon. The operational plan for the Ho Chi Minh Campaign called for Saigon's capture before 1 May. Hanoi wished to avoid the coming monsoon and prevent redeployment of ARVN forces defending the capital. PAVN forces, their morale boosted by their recent victories, rolled on, taking Nha Trang, Cam Ranh and Da Lat.

On 7 April, three PAVN divisions attacked Xuân Lộc, 40 miles (64 km) northeast of Saigon. For two weeks, fighting raged as the ARVN defenders made a last stand to try to block PAVN advance. On 21 April, however, the exhausted garrison was ordered to withdraw towards Saigon. An embittered and tearful Thiệu resigned, declaring that the US had betrayed South Vietnam. In a scathing attack, he suggested Kissinger had tricked him into signing the Paris peace agreement, promising military aid that failed to materialize. Having transferred power to Trần Văn Hương on 21 April, he left for Taiwan. After having appealed unsuccessfully to Congress for $722 million in emergency aid for South Vietnam, Ford gave a televised speech on 23 April, declaring an end to the War and US aid.