South Vietnam was governed by a Catholic family in a country where most people were Buddhist. Ngo Dinh Diem, president from 1955, had a brother who was archbishop of Hue and another who ran the security services, and his administration inherited from the French colonial state a body of law that treated Buddhism as an association rather than a religion while favouring the church in land, appointments and aid. Charles Keith's history of Vietnamese Catholicism traces how a minority church built under empire found itself, after 1954, holding the levers of a nation.
The crisis broke on 8 May 1963. Days after Catholic flags had flown freely for the archbishop's anniversary, the government enforced a standing ban on religious flags against the Buddhist celebration of Vesak in Hue; a crowd gathered, troops fired, and nine people died. The Buddhist leadership answered with a five point petition and with a campaign of vigils, fasts and marches. On 11 June the elderly monk Thich Quang Duc sat down at a Saigon crossroads, was doused in petrol by fellow monks and burned to death without moving, and Malcolm Browne's photograph put the image in front of the world.
Six further monks and nuns followed him that year. In August government forces raided the pagodas and arrested more than a thousand monks, and on 1 November the army, with American acquiescence, overthrew and killed Diem.