Sejo of Joseon

Sejo of Joseon (, 2 November 1417 – 23 September 1468, r. 1455–1468) was the seventh king of the Joseon Dynasty of Korea. He was the son of King Sejong and brother of Munjong of Joseon and uncle of Danjong of Joseon, against whom he led a coup d'état to become king himself in 1455.

Biography

Early life 
Born in 1417 as Yi Yu, King  Sejong the Great's second son, he showed great ability at archery, horse riding and martial arts. He was also a brilliant military commander, though he never went to the battlefront himself. He became Grand Prince Suyang () in 1428, the name by which he was better known.

Following King Sejong's death, Suyang's ill brother, Munjong, took the throne but soon died. The crown passed to his 12-year-old son, Danjong. The new emperor  was too young to rule the nation, and all political processes were controlled by then-premier Hwangbo In and General Kim Jongseo, who was vice-premier. 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 on 10 November (10th day of the 10th lunar month) 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, Anpyeong, first sending him into exile, then sentencing him to death.

Reign
Finally in 1455 he forced his powerless young nephew, Danjong, to abdicate, declaring himself seventh king of the Joseon dynasty. Later he demoted Danjong to prince and ordered him to be poisoned after his younger brother, Grand Prince Geumsung, and later six scholars including Seong Sam-mun, Pak Paeng-nyeon, and Yi Gae plotted to remove Suyang from power in an attempt to put Danjong back on the throne.

Despite having snatched the throne from his young nephew and killing many people in the process, he proved himself one of the most able rulers and administrators in Korean history. First, he strengthened the monarchy established by King Taejong by weakening the power of the prime minister and bringing staff directly under the king's control. He also strengthened the administrative system, which had also been introduced by Taejong, enabling the government to determine exact population numbers and to mobilize troops effectively. Just like Taejong, he was a hardliner with regards to foreign policy and attacked the Jurchens on the northern front in 1460 (오랑캐/兀良哈) and 1467 (호리개/胡里改). He also revised the land ordinance to improve the national economy. He executed scholars from King Sejong's era for plotting against him, but encouraged publication of history, economics, agricultural, and religious books.

Last years 
Most importantly, he compiled the Grand Code for State Administration, which became the cornerstone of dynastic administration and provided the first form of constitutional law in a written form in Korea. He died in 1468, and the throne passed to his weak son, Yejong.

Family

Father: King Sejong of Joseon (15 May 1397 – 8 April 1450) (세종)
Grandfather: King Taejong of Joseon (13 June 1367 – 30 May 1422) (조선 태종)
Grandmother: Queen Wongyeong of the Yeoheung Min clan (29 July 1365 – 18 August 1420) (원경왕후 민씨)
Mother: Queen Soheon of the Cheongsong Shim clan (12 October 1395 – 19 April 1446) (소헌왕후 심씨)
Grandfather: Shim On (1375 – 18 January 1419) (심온)
Grandmother: Lady Ahn of the Sunheung Ahn clan (? – 1444) (순흥 안씨)
Consorts and their Respective Issue(s):
 Queen Jeonghui of the Papyeong Yun clan (8 December 1418 – 6 May 1483) (정희왕후 윤씨)
 Yi Jang, Crown Prince Uigyeong (1438 – 2 September 1457) (이장 의경세자)
 Princess Uisuk (1442 – 3 December 1477) (의숙공주)
 Yi Hwang, Grand Prince Haeyang (14 January 1450 – 31 December 1469) (이황 해양대군)
 Yi Se-Hui (이세희) or Princess Uiryeong (의령공주) or Princess Uihwa (의화공주) 
 Royal Noble Consort Geun of the Seonsan Park clan (1425 – ?) (근빈 박씨)
 Yi Seo, Prince Deokwon (6 March 1449 – 22 July 1498) (이서 덕원군) 
 Yi Seong, Prince Changwon (1458 – 1484) (이성 창원군) 
 Deposed Consort So-yong of the Park clan (폐 소용 박씨)
 Unnamed son (Died in childhood)
 Consort Suk-won of the Goryeong Shin clan (숙원 신씨)

Books compiled by Sejo
Sejo of Joseon compiled a number of books based on his interests. One includes Seokbosangjeol, a biography of Gautama Buddha. He also created two other books:

 Wolin sukbo (월인석보, 月印釋譜) 
 Yukdae byungyo (역대병요, 歷代兵要)

His full posthumous name
 King Sejo Hyejang Sungcheon Chedo Yeolmun Yeongmu Jideok Yunggong Seongsin Myeongye Heumsuk Inhyo the Great of Korea
 세조혜장승천체도열문영무지덕융공성신명예흠숙인효대왕
 世祖惠莊承天體道烈文英武至德隆功聖神明睿欽肅仁孝大王

Depiction in arts and media
 Portrayed by Kim Al-eum in the 1983 MBC TV series The King of Chudong Palace.
 Portrayed by Nam Sung-woo in the 1984-1985 MBC TV series 500 Years of Joseon: The Ume Tree in the Midst of the Snow.
 Portrayed by Seo In-seok in the 1994 KBS2 TV series Han Myung-hoi.
 Portrayed by Im Dong-jin in the 1998-2000 KBS1 TV series The King and the Queen.
 Portrayed by Choi Bong-sik in the 2007 KBS2 TV series Sayuksin.
 Portrayed by Kim Byung-se in the 2007-2008 SBS TV series The King and I.
 Portrayed by Kim Yeong-cheol in the 2011 KBS2 TV series The Princess' Man
 Portrayed by Kim Young-ho in the 2011 JTBC TV series Insu, The Queen Mother.
 Portrayed by Lee Jung-jae in the 2013 film The Face Reader.
 Portrayed by Go Young-bin in the 2016 KBS1 TV series Jang Yeong-sil.

See also
 List of Korean monarchs#Joseon
 Korean-Jurchen border conflicts

References

Category:Joseon rulers
Category:1417 births
Category:1468 deaths
Category:15th-century Korean monarchs
Category:Joseon dynasty Buddhists
Category:Korean Buddhist monarchs
Category:Regents of Korea