ideological basis on which to build a country. Subsequently, this role was ceded to Confucianism. Vietnamese Buddhism reached its zenith during the Lý dynasty (1009–1225), beginning with the founder Lý Thái Tổ, who was raised in a Buddhist temple. All of the emperors during the Lý dynasty professed and sanctioned Buddhism as the state religion. This endured with the Trần dynasty (1225–1400), but Buddhism had to share the stage with the emerging growth of Confucianism. By the 15th century, Buddhism fell out of favor with the court during the Later Lê dynasty, although still popular with the masses. Officials like Lê Quát attacked it as heretical and wasteful. It was not until the 19th century that Buddhism regained some stature under the Nguyễn dynasty, which accorded royal support. A Buddhist revival movement (Chấn hưng Phật giáo) emerged in the 1920s in an effort to reform and strengthen institutional Buddhism, which had lost grounds to the spread of Christianity and the growth of other faiths under French rule. The movement continued into the 1950s. Republican period From 1954 to 1975, Vietnam was split into North and South Vietnam. In a country where surveys of the religious composition estimated the Buddhist majority to be approximately 50 to 70 percent, South Vietnamese President Ngô Đình Diệm's policies generated claims of religious bias. As a member of the Catholic Vietnamese minority, he pursued pro-Catholic policies that antagonized many Buddhists. In May 1963, in the central city of Huế, where Diệm's elder brother Ngô Đình Thục was the archbishop, Buddhists were prohibited from displaying Buddhist flags during Vesak celebrations. Yet few days earlier, Catholics were allowed to fly religious flags at a celebration in honour of the newly-seated archbishop. This led to widespread protest against the government; troops were sent in, and nine civilians were killed in the confrontations. This led to mass rallies against Diệm's government, termed as the Buddhist crisis. The conflicts culminated in Thích Quảng Đức's self-immolation by lighting himself on fire in protest of the persecution of Buddhists. President Diệm's younger brother Ngô Đình Nhu favored strong-armed tactics, and Army of the Republic of Vietnam Special Forces engaged in the Xá Lợi Pagoda raids, killing estimated hundreds. Dismayed by the public outrage, the U.S. government withdrew support for the regime. President Diệm was deposed and killed in the 1963 coup. Political strength of the Buddhists grew in the 1960s as different