In June of 1963, Vietnamese Mahayana Buddhist monk Thích Quang Duc burned himself to death at a busy intersection in Saigon. He was attempting to show that to fight all forms of oppression on equal terms, Buddhism too, needed to have its martyrs.
The self-immolation was done in protest to the South Vietnamese Diem regime’s pro-catholic policies and discriminatory Buddhist laws. In particular this was a response to the banning of the Buddhist flag, just 2 days after Diem had held a very public ceremony displaying crosses; earlier in his rule he had dedicated Vietnam to Jesus and the Catholic Church. The growing resentment of Buddhists under Diem was one of the underlying issues of South Vietnam, and eventually led to a coup to put in place a leader who would not alienate Buddhists, who made up 70-90% of Vietnam’s population.