After Park Chung Hee's assassination in late October of 1979 South Korea went through a period of political liberalization but this liberalization was ended by the military coup d'etat led by Chun Doo Hwan. There were several factors responsible for the overthrow of the legitimate government of South Korea by the younger generation of military leaders:

• The Korean War generation of generals had been discriminating against the younger, better-educated officers of Chun and Roh's generation. This discrimination was moving from merely not appointing them to actually suppressing them.
• The distrust of a feudal society for the seeming disorder and uncertainty of democratic processes.
• The ambition and greed for power of the new generation of the military.

The crisis times of the Korean War resulted in soldiers with very little formal training rising to the level of generals. After the Korean War, under U.S. guidance, South Korea provided for four years of training of the younger officers at the Korean Military Academy. In addition many South Korean officers were taken to the U.S. for advanced training. The older generation of military officers were enjoying positions of power and prestige which they feared would end once a substantial number of the new generation of officers were promoted to positions of power. Therefore the older generation based promotion on loyalty to their class and not on ability and training. As the resentment built up the older generation began to fear a coup and may have been planning to transfer the leaders of the new generation away from Seoul to places distant from the centers of power.

Chun Doo Hwan attempted to dispose the top leadership of the Army by sending military units to arrest them on December 12th of 1979 under the pretext that they were somehow implicated in the assassination of Park Chung Hee.

The two key military leaders to be arrested were the Martial Law Commander, Chung Seung Wha, and the Defense Minister, Noh Jae Hyun. Chun's military squad captured the Martial Law Commander but only after a shoot out with the Commander's guards. The shots alerted the Defense Minister who fled to asylum at the American military base nearby. This failure to capture the Defense Minister put the coup in risk of failure. Few in Seoul knew what was happening and no one knew for sure what the outcome would be. When Chun could not get support elsewhere he did the unforgivable; he withdrew troops under his command from the frontlines facing the North Korean Army on the Demilitarized Zone to support his coup. This was treason of a high order and many, particularly American military figures, never foregave Chun for risking a North Korean takeover of Seoul for the sake of his own political ambitions.

Chun consolidated his control of the South Korean military over a matter of months and finally emerged as the political leader of South Korea. A crucial stage in this emergence occurred in April of 1980 when Chun appointed himself head of the Korean Central Intelligence Agency. Student and worker protests, strikes and riots were frightening the general public and helped Chun carry out his imposition of martial law on May 18th of 1980. The declaration of martial law provoked protests around the country but no where more strongly than in Cholla province in southwestern Korea. In the city of Kwangju a full scale rebellion ensued which lasted for ten days and ended only when the army stormed the city. The rebellion against Chun's martial law was put down only at the cost of thousands of lives and the massacre at Kwangju poisoned South Korea's politics for more than a decade.