General Paik Sun-yup is the first 4-star general in the history of the ROK Armed Forces. Paik successively filled the positions of commander of the First Field Army, the Army Chief of Staff, and the Chairman for the ROK Joint Chiefs of Staff until his retirement from the army in May 1960. He was appointed Ambassador to the Republic of China on Taiwan in 1960, to France in 1961, and to Canada in 1965. From 1969 to 1971, he served as Minister of Transportation and launched the construction of the Seoul Metropolitan Subway.