Ngô Đình Diệm was a South Vietnamese politician. A former mandarin of the Nguyễn dynasty, he was named Prime Minister of the State of Vietnam by Head of State Bảo Đại in 1954. In October 1955, after winning a heavily rigged referendum, he deposed Bảo Đại and established the first Republic of Vietnam, with himself as president. He was a leader of the Catholic element and was opposed by Buddhists. In November 1963, after constant Buddhist protests and non-violent resistance, Diệm was assassinated during a CIA-backed coup d'état, along with his brother, Ngô Đình Nhu, by Nguyễn Văn Nhung, the aide of the leader of the Army of Republic of Vietnam, General Dương Văn Minh. Diệm has been a controversial historical figure in historiography on the Vietnam War. Some historians portrayed him as a tool of the U.S. policymakers, some considered him an avatar of Vietnamese tradition. Nevertheless, some recent studies have portrayed Diệm from a more Vietnamese-centred perspective as a competent leader with his own vision on nation building and modernisation of South Vietnam.