After the Catholic Ngô Đình Diệm came to power in South Vietnam , backed by the United States , he favoured his relatives and co-religionists over Buddhists . Though Buddhists made up 80 % of Vietnam 's population , Catholics were given high positions in the army and civil service . Half of the 123 National Assembly members were Catholic . Buddhists also required special government permits to hold large meetings , a stipulation generally made for meetings of trade unions . In May 1963 , the government forbade the flying of Buddhist flags on Vesak . After Buddhist protesters clashed with government troops , nine people were killed . In protest , the Buddhist monk Thích Quảng Đức burned himself to death in Saigon . On August 21 , the Xá Lợi Pagoda raids led to a death toll estimated in the hundreds
Xá Lợi Pagoda raids
Xá Lợi Pagoda raids
Persecution of Buddhists