Daejonggyo leader and independence fighter; head of the Jungwangdan and the Northern Military Administration; chief of the Korean Independence Army Corps; Order of Merit for National Foundation, Independence Medal

| Life | 1881 ~ 1921 |
| Era | 일제강점기 |
| Clan | 이천 서씨 |
Seo Il (1881-1921), of the Icheon Seo clan, was an independence activist from Gyeongwon, North Hamgyeong. His real name was Seo Gi-hak and his pen name Baekpo. He graduated from a normal school in Gyeongseong county in 1902, taught, and after the 1910 annexation fled to Manchuria in 1911, where he met the Daejonggyo leader Na Cheol and joined that religion the following year.
He founded the Jungwangdan, centered on Daejonggyo believers, and became its head. In 1919 he signed the Declaration of Korean Independence in Jilin with 39 others including Kim Jwa-jin. After the March First Movement the group was reorganized as the Daehan Jeongui-dan and then as the Korean Military Administration (the 'Northern Military Administration'), with Seo Il as its chief; Kim Jwa-jin and Yi Beom-seok also belonged to it.
In 1921 he merged independence units into the Korean Independence Army Corps, but on 28 June the Free City (Svobodny) Incident left many comrades dead. Taking responsibility, he ended his life on 28 August in Mishan by stopping his breath. He was posthumously awarded the Order of Merit for National Foundation, Independence Medal, in 1962 and chosen Independence Fighter of the Month in August 1992.
Daejonggyo, a religion venerating Dangun, was revived by Na Cheol in 1909 and became a spiritual root of the independence movement centered on Manchuria. The Jungwangdan Seo Il led took its name from this revival. He valued both armed struggle and national education, and the Northern Military Administration is the group associated with the 1920 anti-Japanese fighting around Cheongsanri.
Wikipedia's article on Seo Il does not describe his direct role in the Cheongsanri battle, so command details are better read in accounts of Kim Jwa-jin and Yi Beom-seok.
On 28 June 1921 at Svobodny in Russia, clashes among independence units and Soviet intervention caused heavy casualties, a deep wound for the Manchurian movement. Seo Il took responsibility and ended his life two months later in Mishan. A monument bearing his words about the loss of comrades stands at the Independence Hall of Korea.
Tomb location not confirmed (died in Mishan). A quotation monument stands at the Independence Hall of Korea.
His wife was of the Chae clan; daughters Seo Mo and Seo Juk-cheong, son-in-law Choe Gwan, son Seo Yun-je (1908-1969, also an independence activist), daughter-in-law Gwon and grandsons Seo Gyeong-seop and Seo Man-seop are recorded. See also the Icheon Seo clan page.