President Syngman Rhee found it difficult to govern and had to resort to illegal methods on several occasions in 1952 to maintain his authority. He thus arrested the opposition deputies in 1958, leaving him to sit in the assembly as the deputies of his party, after being re-elected for a third time in 1956. This despotic way of leading, which set the tone of 40 years which were to follow, raised a strong popular discontent. Numerous protests broke out in the country in 1960 because of electoral fraud, first in universities and then in many cities. On April 26, 1960, despite a bloody crackdown and the application of martial law, Syngman Rhee finally resigned and went into exile in Hawaii, where he died 9 years later.
Yun Boseon was elected in July and formed a government unable to run the country, then in the midst of an economic crisis. A coup of officers led by Park Chung-hee put an end to the demonstrations in May 1961, but forced Yun Boseon to resign in 1962. Helped by Kim Jong-Pil, Park arrested opponents, then approved a new constitution in December 1962 , which extends the powers of the president. He left the army and was elected in December 1963. He opened an era of economic prosperity, but his regime became more and more authoritarian. He normalized relations with North Korea by signing an agreement for peaceful reunification in 1972. The same year, the dissolution of the Assembly and the launch of Yusin, the Constitution of the "Renovation", gave more power to the president . He was finally assassinated in October 1979 by the director of the secret service, which he himself had created in 1961. His regime is however credited with the modernization of Korea, especially that of the countryside by the Saemaeul movement and of the "miracle" economic.
The election of Choi Gyu-ha generates violent pro-democracy protests. Chun Doo-hwan, who had led the bloody May crackdowns in Gwangju, seized power in a military coup in August 1980, after Choi's resignation. The numerous human rights violations, as well as the financial and political scandals of his government tarnished his popularity, to the point that he did not stand for re-election in 1987. He presented as successor a man from his party, Roh Tae -woo, who is, for the first time, elected by universal suffrage and cannot stop the march towards democratization. The 1988 Olympic Games brought a new Korea onto the international stage. Relations with North Korea improved, especially in 1990 with the inter-ministerial meetings that took place between Pyongyang and Seoul.
Korea's rapid economic and demographic development from the 1960s onward gradually transformed Seoul into an ultra-modern megalopolis. The 1988 Olympic Games launched the development of the south of the Han River, still occupied fifteen years earlier by rice fields. Urbanization has not always followed a determined and coherent plan, but due to the current congestion, the city of Seoul is more sensitive to the problems of the environment and the living environment. The population has also started to decline, attracted by new satellite towns and those in the surrounding active province of Gyeonggi-do.
The Arrival of Democracy: In December 1992, Kin Young-sam was elected president. Korea joins O.C.D.E. in 1996, and entered the big leagues. During Kim Young-sam's presidency, however, numerous corruption scandals erupted. Former presidents Chun Doo-hwan and Roh Tae-woo were tried in 1996 and then sentenced for receiving millions of dollars from the chaebols. Kim Young-sam's son himself is accused of insider trading and corruption. Kim Young-sam's party, whose responsibility is mentioned in the economic crisis that hit the country at the end of 1997, was defeated by its rival Kim Dae-jung in December of the same year. The latter inherits a delicate situation in this "F.M.I period". The start of his administration, however, was marked by openness, towards Japan and especially towards North Korea. The year 2000 was thus marked by the inter-Korean Durand summit, which the South Korean president would meet with his North Korean counterpart in Pyongyang, a historic first which won Kim Dae-jung the Nobel Peace Prize. He is also credited with dramatically reviving the Korean economy after the crisis. The end of his mandate was however overshadowed by numerous scandals: two of his sons were accused of trading in influence.