In 1884, Seo Jae-Pil, following Kim Okgyun, was involved in the Kapsin Coup, a radical attempt to overturn the old regime and establish equality among people. He was appointed the Vice-Minister of Defense. The coup was aborted in three days, as China intervened by sending military troops. Convicted of treason, Seo Jae-Pil lost his whole family and had to flee Korea to save his life.