Chang Myon
The Second Republic was founded during the April Revolution mass protests against President Syngman Rhee, succeeding the First Republic and establishing a parliamentary government under President Yun Bo-seon and Prime Minister Chang Myon. The Second Republic ended Rhee's authoritarianism and repression, formed a liberal democracy, and formulated the first Five-Year Plans to develop the neglected economy. The Second Republic's failure to improve South Korea's political and economic issues led to instability, and after thirteen months it was overthrown by the South Korean Army in the May 16 coup led by Park Chung-hee. The Second Republic was replaced by a provisional military government under the Supreme Council for National Reconstruction, leading to the Third Republic of Korea.