Supreme Council for National Reconstruction in the context of "Second Republic of Korea"

The May 16 military coup d'état (Korean: 5·16 군사정변) or the May 16 Military Revolution (Korean: 5·16 군사혁명) was a military coup d'état in South Korea in 1961, organized and carried out by Park Chung Hee and his allies who formed the Military Revolutionary Committee, nominally led by Army Chief of Staff Chang Do-yong after the latter's acquiescence on the day of the coup. The coup rendered powerless the democratically elected government of Prime Minister Chang Myon and President Yun Posun, and ended the Second Republic, installing a reformist military Supreme Council for National Reconstruction effectively led by Park, who took over as chairman after Chang's arrest in July.

The coup was instrumental in bringing to power a new developmentalist elite and in laying the foundations for the rapid industrialization of South Korea under Park's leadership, but its legacy is controversial for the suppression of democracy and civil liberties it entailed, and the purges enacted in its wake. Termed the "May 16 Military Revolution" by Park and his allies, "a new, mature national debut of spirit", the coup's nature as a "revolution" is controversial and its evaluation contested.

Park Chung Hee (Korean: 박정희; [pak̚.tɕ͈ʌŋ.çi] ; 14 November 1917 – 26 October 1979) was a South Korean politician and army officer who served as the third president of South Korea from 1962 after he seized power in the May 16 coup of 1961 until his assassination in 1979. His regime oversaw a period of intense economic growth and transformation, making Park one of the most consequential leaders in Korean history, although his legacy as a military dictator remains a bitter subject.

Before his presidency, Park was the second-highest-ranking officer in the South Korean army. His coup brought an end to the interim Second Republic of Korea. After serving for two years as chairman of the military junta, he was elected president in 1963, ushering in the Third Republic. A firm anti-communist, he continued to maintain close ties with the United States, which had maintained a large Army garrison in the country since the end of the Korean War. He supported American military involvement in Southeast Asia, and sent South Korean troops to fight in Vietnam soon after seizing power. Park began a series of economic reforms that eventually led to rapid and unprecedented economic growth and industrialization, a phenomenon that is now known as the Miracle on the Han River. This made South Korea one of the fastest growing economies of the 1960s and 1970s, albeit with costs to labor rights. This era also saw the formation of chaebols: family companies supported by the state similar to the Japanese zaibatsu. Examples of significant chaebols include Hyundai, LG, and Samsung.

The Third Republic of Korea (Korean: 제3공화국; RR: Je sam gonghwaguk; lit. "Third Republic") was the government of South Korea from 17 December 1963 to 21 November 1972. The Third Republic was founded on the dissolution of the Supreme Council for National Reconstruction that overthrew the Second Republic and established a military government in May 1961. Park Chung Hee, the Chairman of the Supreme Council, was elected President of South Korea in the 1963 presidential election.

The Third Republic was presented as a return to civilian government under the National Assembly but in practice was a dictatorship under Park, Supreme Council members, and the Democratic Republican Party. The Third Republic prioritized South Korea's economic development, anti-communism, and strengthening ties with the United States and Japan.