This study aims to identify Oh Young-Sun who had actively participated in educational activity and independence movement in Korea, Manchuria, Yunhaeju, and interim administration of Shanghai from the latter era of the Choson Dynasty to early in 1930s for more than 30 years.
Oh Young-Sun was born in Goyang-gun, Gyeonggi-do in 1886. He learned both modern science and military science from Paejae Haktang, Military Attache School of the Korean Empire, and the School of Physics in Tokyo. Based on this knowledge, he engaged in educational activities in Bochang school in Gaeseong and Hyupsin middle school in Seongjin with his father-in-law, Lee Dong-Hui. Around 1913, he exiled to Manchuria and instilled national consciousness to students as teacher in Gwangseong school, Dongrim military academy, and Bugil middle school. After he went to Yunhaeju of Russia at the end of 1917, he joined Shinhanchon(New Korean Village in Vladivostok) Folkmoot, Han-In Sinbo(Newspaper), Korean National Assembly(called as Daehan Gukmin Euhoe), and Young Men''s Christian Association.
When his father-in-law, Lee Dong-Hui became the prime minister of the Provisional Government of Korea in Shanghai in 1919, Oh Young-Sun assisted him as chief secretary of the State Council. However, Oh Young-Sun disagreed with Lee Dong-Hui regarding the purpose of the money borrowed from Russia. Nevertheless, Oh Young-Sun still remained in the Provisional Government of Korea in Shanghai and worked as minister of the Provisional Government of Korea in Shanghai in judicial, foreign, and military affairs. He also worked as head director of Korean Red Cross, member of Shanghai Overseas Korean Residents Group in educational affairs, and member of Korea Working Soldiers Association(Nobyunghoe). In 1922, he introduced a motion of no-confidence in Lee Seung-Man and his ministers as member of the Provisional Assembly in Shanghai. Particularly in National Representatives'' Congress, he mediated reorganization faction and non-reorganization faction although he belonged to reorganization faction. In 1925, he arrived at an agreement when he was dispatched to Chung Eui Boo as head of the interim government. In 1926, he organized Association for Promoting Independence with Ahn Tae-Geun and Yeo Un-Hyung and advocated the unity of Korean independence fighters.
However, Oh Young-Sun could not work any longer since 1931 owing to illness. He remained in Shanghai when the Provisional Government of Korea in Shanghai moved to Hangzhou in 1932 and died in 1939.
Oh Young-Sun can be evaluated as a significant person in that he devoted himself to the nationality education in Korea, Manchuria, and Yunhaeju in the 1910s, assumed an important post the Provisional Government of Korea in Shanghai in the 1920s, and sought arbitration and unity between independence movement organizations.