to make reforms and changes of policy within the government. As a result, he was labeled by Diệm's government to be a "political opposition." In February 1959, he was elected as a congressman representing the Saigon constituency. He then joined the Great National Solidarity Front with Nguyễn Tường Tam to oppose the government. On April 26, 1960, he and 17 dignitaries signed the proclamation, later known as the "Caravelle Manifesto," criticizing the government's mistakes and demanding that the President make reforms in policies. This made him become a thorn in the eyes of the government. On the occasion of the failed coup on 11 November 1960, he was accused of supporting the coup by the government and imprisoned. On the night of 11 July 1963, he was sentenced to 8 years in prison by a special military court in Saigon along with Phan Quang Đán, Vũ Hồng Khanh, and Bùi Lương. When defending himself in court, he said: "If I am guilty, then I only have one crime, which is to expel the French from Saigon, sin for the sake of the Nation!." On 31 July 1963, he was exiled to Côn Đảo Prison to serve his sentence. However, only 3 months later, another coup broke out, overthrowing and assassinating President Diệm, he was released from prison and returned to Saigon. Chief of State of the Republic of Vietnam (1964-1965) After the "Three Heads" crisis, on 8 September 1964, he was invited to the National Synod by the Provisional Leadership Committee (the Three Heads). On 27 September, the Synod elected Phan Khắc Sửu as President. He presided over the Synod that drafted the 20 October 1964 Covenant to replace the 4 November 1963 Provisional Charter, which placed power in the hands of the military to relinquish power and national sovereignty to elected representatives. On 24 October, he was nominated by the Synod for the position of Chief of State. After taking office as Chief of State, on 4 November 1964, he appointed Trần Văn Hương as prime minister, he was the second civilian prime minister since the First Republic of President Ngô Đình Diệm was overthrown by the rebels. However, Trần Văn Hương's government was quickly paralyzed by the opposition of many circles as well as the lack of cooperation of the Military Council. The crisis lasted for 2 months, on 18 December 1964, General Nguyễn Khánh led the young