Sejo of Joseon

Not to be confused with Sejong of Joseon.

Sejo of Joseon (2 November 1417 – 23 September 1468), personal name Yi Yu (Korean: 이유; Hanja: 李瑈), sometimes known as Grand Prince Suyang (Korean: 수양대군; Hanja: 首陽大君), was the seventh ruler of the Joseon dynasty of Korea. He was the second son of Sejong the Great and the uncle of King Danjong, against whom he led a coup d'état in 1455.

Sejo of Joseon 朝鮮世祖 조선 세조
King Emeritus of Joseon
Tenure	22 – 23 September 1468
Predecessor	Danjong of Joseon
Successor	Jungjong of Joseon
King of Joseon
Reign	24 June 1455 – 22 September 1468
Coronation	Geunjeongjeon Hall, Gyeongbok Palace, Hanseong, Kingdom of Joseon
Predecessor	Danjong of Joseon
Successor	Yejong of Joseon
Chief State Councillor
In office	10 October 1453 – 24 June 1455
Predecessor	Hwangbo In
Successor	Jeong In-ji
Monarch	Danjong of Joseon
Born	Yi Yu (이유, 李瑈) 2 November 1417 Grand Prince Chungnyeong's private residence, Hanseong, Kingdom of Joseon
Died	23 September 1468(1468-09-23) (aged 50) Sugang Palace, Hanseong, Kingdom of Joseon
Burial	Gwangneung Tombs, Namyangju, Gyeonggi Province, South Korea
Spouse(s)	Queen Jeonghui ​ (m. 1428)​
Issue	Yejong of Joseon
Posthumous name Joseon dynasty: King Jideok Yunggong Seongsin Myeongye Heumsuk Inhyo the Great 지덕융공성신명예흠숙인효대왕 至德隆功聖神明睿欽肅仁孝大王 Ming dynasty: Hyejang (혜장, 惠莊) Temple name Sejo (세조, 世祖)
Clan	Jeonju Yi clan
Dynasty	House of Yi
Father	Sejong of Joseon
Mother	Queen Soheon
Religion	Korean Confucianism (Neo-Confucianism) → Korean Buddhism
Signature

Korean name
Hangul	세조
Hanja	世祖
Revised Romanization	Sejo
McCune–Reischauer	Secho
Birth name
Hangul	이유
Hanja	李瑈
Revised Romanization	I Yu
McCune–Reischauer	Yi Yu
Courtesy name
Hangul	수지
Hanja	粹之
Revised Romanization	Suji
McCune–Reischauer	Suchi

Biography

Early life

Born in 1417 as the fourth child and second son of Grand Prince Chungnyeong (future King Sejong) by his primary wife, Lady Shim of the Cheongsong Shim clan (future Queen Soheon), he showed great ability at archery, horse riding and martial arts, and was also a brilliant military commander, though he never went to the battlefront himself. In 1428, he received the title Grand Prince Suyang by which he is better known.

Rise to power

Following the death of King Sejong in 1450, Suyang's ill brother, Yi Hyang (later known as King Munjong), took the throne but died two years later, and the crown passed to his 12-year-old son, Yi Hong-wi (posthumously named King Danjong). The new monarch was too young to rule the nation, and the government was controlled by Chief State Councillor Hwangbo In and General Gim Jong-seo, who was the Left State Councillor. As Gim Jong-seo and his faction used the chance to extend the power of court officials against royal family members, the tension between him and Suyang greatly increased; not only Suyang himself, but his younger brother, Grand Prince Anpyeong, also sought an opportunity to take control of the country.^[1]

In order to court the support of the Ming dynasty, Suyang became an ambassador in 1452. He also surrounded himself with trusted allies, including his famous tactician, Han Myeong-hoe, who advised him to take over the government in a coup. In 1453, Suyang killed Gim Jong-seo and his faction, thereby taking the reins of power into his own hands. After the coup, he arrested his own brother, Grand Prince Anpyeong, first sending him into exile, then sentencing him to death.^[1]

Reign

Finally, in 1455 Suyang forced the powerless king to abdicate, declaring himself the new ruler of Joseon (today known by the temple name "Sejo").

After his younger brother Grand Prince Geumsung, and six scholars, including Seong Sam-mun, Park Paeng-nyeon and Yi Gae, plotted to remove him from power in an attempt to put his nephew back on the throne, Suyang demoted the former king from "King Emeritus" (Sangwang; 상왕, 上王) to "Prince Nosan" (Nosan Gun; 노산군, 魯山君) and later ordered him to commit suicide by poison.

Despite having snatched the throne from his young nephew and killing many people in the process, Sejo proved himself one of the ablest rulers and administrators in Korean history. First, he continued King Taejong's legacy of strengthening the monarchy by weakening the power of the State Council and bringing the officials directly under the king's control. He also further developed the administrative system, which had also been introduced by Taejong, enabling the government to determine exact population numbers and to mobilize troops effectively (this caused Yi Si-ae's Rebellion, which he suppressed). Just like Taejong, Sejo was a hardliner concerning 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 and encouraged the publication of history, economy, agriculture, and religion books.

Sejo himself compiled a number of books based on his interests. One of them is Seokbosangjeol, a biography of Gautama Buddha.^[2] The others are Worinseokbo (월인석보, 月印釋譜) and Yeokdaebyeongyo (역대병요, 歷代兵要).

Most importantly, he compiled the Grand Code for State Administration, which became the cornerstone of dynastic administration and provided the first form of written constitutional law in Korea.

Death

Sejo died in 1468, and the throne passed to his sickly second son, Yi Hwang (Yejong of Joseon). His tomb is known as Gwangneung (광릉) and is located in Namyangju, Gyeonggi Province, South Korea.

Family

• Father: King Sejong of Joseon (조선 세종) (15 May 1397 – 8 April 1450)
  • Grandfather: King Taejong of Joseon (조선 태종) (13 June 1367 – 30 May 1422)
  • Grandmother: Queen Wongyeong of the Yeoheung Min clan (원경왕후 민씨) (29 July 1365 – 18 August 1420)
• Mother: Queen Soheon of the Cheongsong Shim clan (소헌왕후 심씨) (12 October 1395 – 19 April 1446)
  • Grandfather: Shim On (심온) (1375 – 18 January 1419)
  • Grandmother: Lady Ahn of the Sunheung Ahn clan (순흥 안씨) (? – 1444)

Consorts and their respective issue(s):

1. Queen Jeonghui of the Papyeong Yun clan (정희왕후 윤씨) (8 December 1418 – 6 May 1483)^[3][4]
   1. Yi Jang, Crown Prince Uigyeong (의경세자 이장) (1438 – 2 September 1457), first son^[5]
   2. Princess Uiryeong (의령공주), first daughter^[6][7][8][9] — Disputed.
   3. Princess Uisuk (의숙공주) (1442 – 3 December 1477), second daughter^[8][10]
   4. Yi Hwang, Grand Prince Haeyang (해양대군 이황) (14 January 1450 – 31 December 1469), third son
2. Royal Noble Consort Geun of the Seonsan Park clan (근빈 박씨) (1425 – ?)^[11][12]
   1. Yi Seo, Prince Deokwon (덕원군 이서) (6 March 1449 – 22 July 1498), second son^{[13][14][15][16]}
   2. Yi Seong, Prince Changwon (창원군 이성) (1458 – 1484), fourth son^[17][18]
3. Deposed Royal Consort So-yong of the Park clan (폐소용 박씨) (? – 1465)^[19][20][21]
   1. Prince Yi A-ji (왕자 이아지) (1459 – 1563), fifth son

Ancestry

Ancestors of Sejo of Joseon

16. Yi Ja-chun, King Hwanjo of Joseon / Ulus Bukha (조선 환조 이자춘) / (吾魯思不花) 8. King Taejo of Joseon (조선 태조) 17. Queen Uihye of the Yeongheung Choe clan (의혜왕후 최씨) 4. King Taejong of Joseon (조선 태종) 18. Han Gyeong, Internal Prince Ancheon (안천부원군 한경) 9. Queen Sinui of the Cheongju Han clan (신의왕후 한씨) 19. Lady Shin of the Saknyeong Shin clan (삭녕 신씨) 2. King Sejong of Joseon (조선 세종) 20. Min Byeon (민변) 10. Min Je, Internal Prince Yeoheung & Duke Mundo (여흥부원군 문도공 민제) 21. Lady Heo of the Yangcheon Heo clan (양천 허씨) 5. Queen Wongyeong of the Yeoheung Min clan (원경왕후 민씨) 22. Song Seon (송선) 11. Lady Song of the Yeosan Song clan (여산 송씨) 23. Lady Ha of the Dalseong Ha clan (달성 하씨) 1. Sejo of Joseon 24. Shim Ryong (심룡) 12. Shim Deok-bu (심덕부) 25. Lady Gim (김씨) 6. Shim On, Internal Prince Cheongcheon & Duke Anhyo (청천부원군 안효공 심온) 26. Mun Pil-dae (문필대) 13. Lady Mun of the Incheon Mun clan (인천 문씨) 3. Queen Soheon of the Cheongsong Shim clan (소헌왕후 심씨) 14. Ahn Cheon-bo (안천보) 7. Lady Ahn of the Sunheung Ahn clan (순흥 안씨) 15. Lady Gim of the Yeongju Gim clan (영주 김씨)

In popular culture

• 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 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.
• Portrayed by Park Hee-soon in the 2019 film Jesters: The Game Changers.

See also

• List of monarchs of Korea
• Korean–Jurchen border conflicts

Notes

1. "세조". terms.naver.com (in Korean). Retrieved 4 February 2022.
2. "Life History and Sermon of Buddha Abstracted from Buddhist Scriptures". World Digital Library. 1447. Retrieved 24 May 2013.
3. Daughter of Yun Beon, Internal Prince Papyeong & Duke Jeongjeong (파평부원군 정정공 윤번); and Lady Yi of the Incheon Yi clan (인천 이씨), also known as Grand Internal Princess Consort Heungnyeong (흥녕부대부인).
4. Married Grand Prince Suyang in 1428.
5. Known as Prince Dowon (Dowon Gun; 도원군) before his father took the throne.
6. She is only mentioned in an unofficial history (야사, 野史) called Geumgye Pildam (금계필담, 錦溪筆談) written in 1873 by Seo Yu-yeong (서유영). The sole reference at her existence in an official document is a passage from the Annals of the Joseon dynasty, where Grand Prince Suyang (as Sejo was still known at the time) is recorded as having "one son and two daughters" [Sejong Sillok, year 28].
7. Her personal name was Yi Se-hui (이세희, 李世熺).
8. As a legitimate daughter of the king, her title properly translates to "Royal Princess" (Gongju; 공주, 公主).
9. Married Gim Cha-dong (김차동), a great-grandson of Gim Jong-seo. They had no issue.
10. Married Jeong Hyeon-jo (정현조), created Prince Haseong (하성군); son of Jeong In-ji, Duke Munseong (문성공 정인지), and later Chief State Councillor.
11. Formerly known as Gwi-in (first junior rank concubine; 귀인, 貴人) or by the title "Lady Jasu" (Jasugung; literally "Palace of Motherly Kindness and Long Life"; 자수궁, 慈壽宮), she was elevated to Bin (first senior rank concubine; 귀인, 貴人) and "Lady Changsu" (Changsugung; literally "Palace of Propriety and Long Life"; 창수궁, 昌壽宮) in 1483.
12. Elder sister of Park Paeng-nyeon (박팽년), later one of the six martyred ministers.
13. With his first wife, Lady Gim of the Gyeongju Gim clan (경주 김씨), also known as Princess Consort Imcheon (임천군부인) (1447 – 1481), he had 2 sons: Yi Jeok, Prince Yeonseong (연성군 이적) (1464 – 1525), and Yi Hwal, Prince Deokjin (덕진군 이활).
14. With his second wife, Lady Yun of the Haman Yun clan (함안 윤씨), also known as Princess Consort Bongsan (봉산군부인) (? – 12 August 1450), he had 3 sons.
15. With his third wife, Lady Yang of the Cheongju Yang clan (청주 양씨), also known as Princess Consort Anseong (안성군부인) (1451 – 1504), he had 2 sons: Yi Gam (이감) (1478 – 1534) and Yi Shim (이심) (1489 – 1521).
16. With his fourth wife, Lady Seong of the Changnyeong Seong clan (창녕 성씨), also known as Princess Consort Changnyeong (창녕군부인) (1453 – 1515), he had 3 sons: Prince Songseon (숭선군) (1488 – 1544), an unnamed son, and Prince Cheongbu (청부군) (1494 – 1545).
17. His three wives were Lady No of Gyoha No clan (교하 노씨), also known as Princess Consort Deokyang (덕양군부인); Lady Jeong of the Gwangju Jeong clan (광주 정씨), also known as Princess Consort Gwangseong (광성군부인); and Lady Han of the Cheongju Han clan (청주 한씨).
18. As his marriages failed to produce any children, he adopted Yi Hwal, Prince Deokjin (덕진군 이활), one of his older brother's sons.
19. Her personal name was Park Deok-jung (박덕중, 朴德中).
20. Former concubine of the third senior rank (So-yong; 소용, 昭容).
21. She was executed by hanging in the 11th year of Sejo’s reign.

Sejo of Joseon House of Yi Born: 2 November 1417 Died: 23 September 1468
Regnal titles
Preceded by Danjong	King of Joseon 24 June 1455 – 22 September 1468	Succeeded by Yejong