Then came in 2506/1963 the persecution of Buddhism and the Buddhist crisis which turned the monks political and militant. The crisis began on the eve of the Visakha Puja Day, May 8, 2506/1963, when the police, to follow an order of the President on the use of flags, tore down some of the Buddhist flags raised for the celebrations. Then followed protests by the Buddhists and violent responses from the government to the degree of destruction and bloodshed. The monks led the people in political demonstrations, hunger strikes and sacrificial suicides by burning themselves to death. It was Thich Quang Duc, a 73-year-old monk, who first performed self-immolation on June 11, 2506/1963. He was followed by a number of monks, nuns and lay Buddhists. Among the five demands of the Buddhists were equality under the law for Buddhists and Catholics, and the free practice and propagation of the Buddhist faith. The event which started as a purely religious issue quickly turned into a test of political power. Madame Nhu, the President's sister-in-law, scorned the Buddhists and condemned them as Communists. She even said, "If another monk barbecues himself, I will clap my hands." On August 21, the Buddhists' headquarters and stronghold at Za Loi pagoda was crushed by Ngo Dinh Nhu and martial law was proclaimed. The American advice to conciliate with the Buddhists was not accepted.
At this point, the American government ordered a stop of support to Nhu and agreed to support the military men who planned to bring down the Ngo family. Then the way for a successful coup had been paved by the Buddhist opposition against the government and the Diem regime was finally overthrown on November 1, 2506/1963, by a military coup d'etat. Ngo Dinh Diem and Ngo Dinh Nhu were both killed.

VIETNAMESE BUDDHISTS REORGANIZE
After the coup of 1963, the Buddhists became a major force in Vietnamese politics, the third power after the Army and the Vietcong. The military group who held power then wanted to win their support, so they approved the Vietnamese Buddhist Reunification Congress held in Saigon from December 21, 2506/1963, to January 3, 2507/1964. The major result of this meeting was the establishment of the Unified Vietnamese Buddhist Church (also called United Buddhist Association) which united the Theravada followers1 with the Mahayana sects and which gave the Buddhists a new type of organization with an ecclesiastical hierarchy, parallel to the government structure.

The governing body at the top of the Unified Vietnamese Buddhist Church was the Assembly of Elders, consisting of about fifty to seventy respected senior monks. The Assembly was presided over by the Patriarch, who was elected to a four-year term from among the members of the Assembly. Under the Assembly was the Vien Hoa Dao, or the Council for the Execution of the Dharma, with a Chairman, three Deputies and a Secretary-General. The Vien Hoa Dao consisted of nine departments or commissions (comparable to government ministries), dealing with Sangha affairs, education, youth affairs, cultural affairs (or art and literature), government for nuns, the laity, social service, construction and finance, and the dissemination of the Dharma. The organization at the provincial and district levels followed the same structure of nine departments and was subject to an electoral system. All the key positions from the heads of the departments from the provincial level upwards were held by monks, whether Mahayana or Theravada.

In addition to these was established the Buddhist Chaplain Corps with welfare programmes for soldiers' families, which in practice became a support for the Buddhist leadership within the Army. In 2507/1964, with the initiative of Thich Nhat Hanh, the Church also created in the Department of Education the Institute of Higher Buddhist Studies in Saigon, which was shortly afterwards, in the same year, transformed into Van Hanh University with Thich Min Chau as its first rector. In 1966, this university had an enrolment of more than 2,000 students.