South Vietnamese Buddhist crisis and coup of 1963
In 1963, many things happened in the Vietnam War, but the Vietnam War, Buddhist crisis and military coup of 1963 were sufficiently complex to warrant a discussion separate from the main Vietnam War article, and even from an article on Ngo Dinh Diem himself. The name here should not suggest Vietnamese Buddhism was monolithic; there were definite political factions within it.
Diem, president of South Vietnam, and his immediate advisors, had been part of the basic war problem for some time. While Diem himself was an ascetic that probably did not personally profit, members of his family, and numerous southern officials, were motivated by opportunities for corruption rather than government by the consent of the governed. Diem demonstrated no real understanding of democracy, and kept power with the Catholic minority. Increasingly bitter interactions with a Buddhist opposition led to a crisis in 1963, with iconic images of monks burning themselves alive in protest. Eventually, Diem was overthrown by a military coup in which he and his most hated brother (and advisor) were shot within minutes of their capture by the soldiers carrying out a coup. While there was a parliament, general democratic government never emerged; the main power in South Vietnam remained with the military leadership until the country was conquered in 1975.
Diem (and his successors) were primarily interested in using the Army of the Republic of Viet Nam (ARVN) as a device to secure power, rather than as a tool to unify the nation and defeat its enemies. Despite American efforts from 1960 through 1972, the situation never decisively improved. Saigon would ultimately lose the war because its large and very well equipped army lacked motivation to support a government.
For a government to prevail in the face of a determined insurgency, special factors usually need to be present. The mot relevant successful example is that of the Philippines, where Ramon Magsaysay, as Defense Minister and then President, prevailed over the Communist-dominated Hukbalahap. His success involved being extremely visible to the people, even in the rural areas, demonstrating real concern, and backing up his deeds with action. He also rooted out corruption in government, which had been a major problem in South Vietnam. In contrast to the aloof and rigid Diem, Magsaysay was a charismatic leader. One of his first acts on assuming the presidency showed the sort of symbolism needed to "capture the hearts and minds": throwing open the guarded gates of the Presidential Palace and inviting the people into "their house". The Presidential Palace of Vietnam was entered only by South Vietnamese military coups, and then by North Vietnamese tanks. Magsaysay, unfortunately, died in an airplane accident.
In Vietnam, the Communist leadership in the North, which dominated the Southern insurgency, had clearly defined political objectives, and a grand strategy, involving military, diplomatic, covert action and psychological operations to achieve those objectives. Whether or not one agreed with those objectives, there was a clear relationship between long-term goals and short-term actions. Its military first focused on guerrilla and raid warfare in the south, simultaneously improving the air defenses of the north. It also spoke to the people's needs at a village level, with a shadow government that indeed was not corrupt, but was quite willing to use terror and other forces to realize its agenda. In the Western sense, there was never a viable democratic alternative during the Vietnam War.
Diem, his personality, and his advisors
Even before addressing more obvious religious conflict, it should be observed that Diem apparently had a Confucian view of his authority being rightful; while he had lived in the West, he did not share Western concepts of government. By most accounts, he personally, although not some of his closest advisors, was ascetic. He compounded his alienation from the public by giving to the Catholic minority, in a country that is majority Buddhists but many smaller religions or sects. Perhaps the most charitable view that could be taken of Diem was that he believed that his personal rectitude freed him from responsibility to the people he governed.
Diem's closest advisors were his brothers, especially the increasingly irrational Ngo Dinh Nhu, his key political advisor, who, as did several of the brothers, have what were effectively private armies. Since Diem himself was a bachelor, his sister-in-law, born Tran Le Xuan but usually called Madame Nhu, acted as official hostess and was extremely visible.
Background of Buddhist resentment
On the order of 1 million Vietnamese moved following partition, the majority going south from the northern area of Tonkin was the heart of the French culture in Vietnam, with the University of Hanoi and its French staff, and where Catholicism was dominant in the villages. " It was from this culture, with partition pending, that between 800,000 and 1 million Catholics came south. Voluntary exiles such as Ngo Dinh Diem also returned to the South. While movement was still allowed until mid-1955, the bulk of the movement came south in a surge. 300,000 airlifted by the U.S. had been closely associated with the French, as soldiers and civil servants, or had lived in Catholic dioceses where the bishops had dominated local rule.
An estimated two-thirds of the Catholic population of the North came South, following their priests, in numbers estimated from 600,000  to 800,000. Along with the Catholic refugees, coming from Tonkin (i.e., the north), various exiles returned. Diem was such an exile; he arrived in Saigon from France on 25 June 1954. and, with U.S. and French support, was named Premier of the State of Vietnam by Emperor Bao Dai, who had just won French assent to "treaties of independence and association" on 4 July.
The Diem government was most comfortable with Catholic coreligionists, who made up approximately 20 percent of the population. The majority was Buddhists, with significant native sects such as the Cao Dai and Hoa Hao. Groups such as the Binh Xuyen were not strictly religious, but certainly did not identify with the Diem government, led by a man from Annam, the lowlands of Central Vietnam (although not the Central Highlands, the semi-autonomous Montagnard homeland). In fairness to Diem, he was placed in a situation where the population had not prepared for self-government, and he had not had the opportunity to connect with the people, especially in the southern areas including Saigon.
U.S. Ambassador Frederick Nolting Jr. believed the U.S. press was especially deceptive with respect to something he always put in quotes, the "Buddhist uprising." He considered it a specific political effort by a newly organized General Association of Vietnamese Buddhists, which Nolting said was not representative of Buddhists.
Diem himself, however, was ill-equipped to connect with the people. Catholicism was not the only basis for his personality and leadership, but also Confucian principles where he ruled by right, rather than the Western concept of the consent of the governed. Personally ascetic, his closest advisors were of his family, and then his coreligionists.
The crisis begins
While there had been long-term resentment by the Buddhists, the situation flared in April 1963. For unclear reasons, the central government ordered the provincial authorities to enforce a ban on the display of all religious flags. This ban had rarely been enforced, but, since the order went out shortly before the major festival, Vesek (informally called Buddha's Birthday), which fell on May 8, many Buddhists perceived this as a direct attack on their customs.
Not long before the enforcement order had been issued, there were many displays of Papal flags, commemorating the 25th anniversary, in the priesthood, of Diem's brother Ngo Dinh Thuc, Catholic Archbishop of Hue. On Buddha's birthday, there was a demonstration, protesting the seemingly selective ban on flags. The enforcement was at the orders of Diem's brother Ngo Dinh Can, who, from a headquarters in Hue, controlled central Vietnam.
Again for unclear reasons, a Civil Guard unit used gunfire against the demonstrators, killing several adults and children. The Diem government described the attack as having been arranged by Viet Cong provocateurs, without strong evidence; the government seemed unwilling to investigate or conciliate.
A Buddhist monk, Thich Quang Duc, calmly walked to a major Saigon intersection on June, sat in the lotus position as acolytes poured gasoline over him, and then struck a cigarette lighter and burned himself to death. Reporters had been alerted by the Buddhists, and photograph of the monk, engulfed in flames, drew worldwide attention to the situation. Madame Nhu's response to this crisis was to refer to "barbecues", while her husband said "if the Buddhists want to have another barbecue, I will be glad to supply the gasoline". It would be hard to imagine less conciliatory language.
For the first time, the Buddhists of Vietnam, generally both factionalized and peaceful, made demands on the Government. Diem's vice president, Nguyen Ngoc Tho, himself a Buddhist, represented the government in the negotiations, apparently with growing personal credibility. 
Diem agreed to what he termed "compromises" on June 16. The fact that they had been able to get any concessions strengthened their unity.
U.S. support weakens in the presence of coup warnings
The breakdown of U.S. support for Diem became more apparent on July 9, when John McCone, Director of Central Intelligence briefed Kennedy on a coup being contemplated by the respected commander of the ARVN, Tran Van Don. Don did not give a specific date for the coup, but suggested it might be in as little as two weeks, and had widespread support from the generals. They felt they had to act before the Viet Cong made more propaganda from the Buddhist persecution; Don said that Buddhist leaders did not believe Diem would keep his agreements made in June. According to Don, Diem believed that agreeing to even reasonable Buddhist demands would encourage them to ask for more. Don also told the CIA officer, Lucien Conein, that the Buddhists were planning more suicides and demonstrations.
Diem was unable to command support from the military or the people, seemingly convinced of his own righteousness, much as he claimed "divine intervention" had protected him during the 1962 bombing of the Presidential Palace.  While his successors were primarily Buddhists, they were still interested in power, and often more corrupt than was Diem. The crisis and aftermath, therefore, was more a matter of power than of theology
The end of the Ngo Regime
As a direct result of the Buddhist crisis, Ngo and his regime was subsequently overthrown.
On August 21, Nhu used the authority of martial law to carry out massive raids on Buddhist pagodas and portrayed those attacks as the responsibility of the ARVN and the CIA. However, the raids were not by ARVN forces at all, but by paramilitary police and Vietnamese Special Forces under the direct command of Le Quang Tung. This prompted key U.S. decisions, expressed in "Cable 243" from Assistant Secretary of State Roger Hilsman, conveying the Administration position to Ambassador Lodge. The Kennedy Administration undertook two fact-finding missions to Vietnam during the late summer/early autumn of 1963. The Krulak-Mendenhall mission and the McNamara-Taylor mission both failed to impress upon Ngo the displeasure of the U.S. regarding South Vietnam's direction or how the international spotlight was damaging relations. As a result of these missions, the Kennedy Administration authorized reducing troop commitments to South Vietnam. Yet, also, plans for a coup were developed in South Vietnam and the U.S. gave them word that the it would not attempt to stop a coup but would also support a successor regime. Ngo and his brother were assassinated on November 1, 1963. The end of the Ngo regime effectively ended the Buddhist crisis.
- , Volume 1, Chapter 4, "U.S. and France in Indochina, 1950-56, The Pentagon Papers, Gravel Edition, Volume 1
- Zolberg, Aristide R.; Astri Suhrke & Sergio Aguayo (1989), Escape from Violence, Oxford University Press, pp. 162-163
- Hasdorff, James C. (January-February 1974), "Vietnam in Retrospect: An Interview with Ambassador Frederick E. Nolting, Jr.", Air University Review
- Gettleman, Marvin E.; Jane Franklin & Marilyn Young et al. (1995), Vietnam and America: A Documented History, Grove Press, p. 218
- John Prados, ed., DCI Briefing, July 9, 1963, JFK and the Diem Coup, vol. George Washington University Electronic Briefing Book No. 101
- , Chapter 4, "The Overthrow of Ngo Dinh Diem, May-November, 1963," Section 2,pp. 201-232, The Pentagon Papers, Gravel Edition, Volume 2
- , Chapter 4, "The Overthrow of Ngo Dinh Diem, May-November, 1963," Section 2, pp. 232-276, The Pentagon Papers, Gravel Edition, Volume 2
- John Prados, ed., State-Saigon Cable 243, August 24, 1963, JFK and the Diem Coup, vol. George Washington University Electronic Briefing Book No. 101