General Kim Jongseo, (hangul: 김종서, hanja: 金宗瑞) (1383 – 10 November 1453) a prominent general, was sent by King Sejong the Great, north to destroy the Manchu in 1433. Kim's military campaign captured several castles, pushed north, and restored Korean territory, roughly the present-day border between North Korea and China.
Following King Sejong's death, Grand Prince Suyang's ill brother, Munjong took the throne but soon died. The crown passed to his 12-year-old son, Danjong. The new king was too young to rule the nation and all political processes were controlled by then-premier Hwangbo In and General Kim Jongseo.
As Kim Jongseo and his faction used the chance to extend the power of court officials against many royal family members, the tension between Kim and Suyang greatly increased; not only Suyang himself, but his younger brother, Grand Prince Anpyeong, also sought an opportunity to take control of the kingdom.
Suyang surrounded himself with trusted allies, including his famous adviser, Han Myung-hoi. Han advised Suyang to take over the government in a coup, and in October 1453, he killed Kim Jongseo and his faction, thereby taking the reins of power into his own hands. After the coup he arrested his own brother, Anpyong, first sending him into exile, then putting him to death.