King Sejo

From New World Encyclopedia
King Sejo
Hangul: 세조
Hanja: 世祖
Revised Romanization: Sejo
McCune-Reischauer: Sejo
Birth name
Hangul: 이유
Hanja: 李瑈
Revised Romanization: I Yu
McCune-Reischauer: I Yu

King Sejo of Joseon (hangul: 세조; hanja: 世祖; 1417-1468, r. 1455-1468) was the seventh king of the Joseon Dynasty of Korea. Born in 1417 as Yi Yu, he was better known as Grand Prince Suyang. The second of King Sejong the Great's many sons, he showed great ability at archery, horse riding, and martial arts. Suyang was also a brilliant military commander, though he never went to the battlefront himself. Although his ascent to the throne was stained with ruthless bloodshed and the forced removal of his nephew from the throne, he went on to prove himself one of the most able rulers and administrators in Korean history.

Suyang's older brother, Munjong

Toward the end of his reign, King Sejong's declining health prompted him to step down from the throne in 1450 and turn the crown over to his eldest son, Munjung, Prince Suyang's older brother. Sejong died later the same year. Munjung had already been helping his ailing father run the country for many years before he actually took the throne. By the time he became King Munjung, his own health was also in decline, and his only son, Danjung was only 10-years-old. Munjung set up a circle of advisors, led by premier Hwangbo In and General Kim Jongseo, who was the vice-premier, to educate Danjong and help him to run the country until he was old enough to stand on his own. In 1452, when Danjong was still only 12, Munjung died and Danjong became King.

Suyang's violent rise to the throne

As Kim Jongseo and his faction used the chance to extend the power of court officials against many royal family members, great tension arose between Kim and Prince Suyang; not only Suyang himself, but his younger brother, Grand Prince Anpyong, also sought an opportunity to take control of the kingdom.

Suyang surrounded himself with trusted allies, including his famous adviser Han Myung-Hoi. Han convinced Suyang to take over control of the government in a coup, and in October 1453, Suyang and his men killed Kim Jongseo and his faction, thereby taking over the reins of power—although Danjong remained on the throne. After the coup, Suyang arrested his younger brother Anpyong, first sending him into exile, then putting him to death. In 1455, he forced his powerless young nephew Danjong to abdicate, and took the throne as King Sejo, the seventh king of the Joseon dynasty. Later he demoted Danjung from retired King to Prince and ordered him into exile. (Danjong's title of King was later restored in 1698 by the court of King Sukjong.) Hearing of plots hatched by his younger brother, Grand Prince Geumsung, and later by six scholars, to remove him from power and restore Danjong to the throne, King Sejo decided it was too dangerous to allow Danjong to live, and arranged for him to be killed in exile.

King Sejo's reign

Despite having snatched the throne from his young nephew, killing many people in the process, Sejo proved himself one of the most able rulers and administrators in Korean history. First, he strengthened the monarchy established by Taejong, by weakening the power of the prime minister and bringing staff directly under the king's control. The Uijongbu, the board of counselors who helped the king rule that had been established by Taejo and Taejong had been intended to give the king support and collective wisdom to assist him in running the country, but in practice, the members of the aristocracy on the board had become too influential, and held too much of the power, so Sejo restructured the government to return more power to the king.

He also strengthened the administrative system, which had also been introduced by Taejong, instituting the Civil Register Act, initiating a census, including the drafting of detailed maps of the country, and renewing the requirement that citizens carry identification tags. These measures enabled the government to determine exact population numbers and to mobilize troops effectively.

There were several rosters of yangban who had been selected as "Merit Subjects" by King Sejo and his predecessors, and they had traditionally been awarded land grants in recognition of their contributions to the kingdom. As the number of Merit Subjects grew, there was not enough land for all of them. Sejo reformed the land grant system so that the merit subjects received the use of land not for life, but only during the period that they actually served in government offices.

Sejo was very interested in medicine. He had seen his father, King Sejong suffer through many ailments, and he had also learned a lot about the medical field as he was treated for his own series of illnesses. In 1463, he published a Treatise on Medicine, which described a ranking of qualifications for physicians, placing a high priority on the physicians' degree of moral commitment to their work.

The 600 year old pine tree that was elevated to 'Imperial Minister' after bowing to King Sejo.

There is a legend that Sejo visited Woljeongsa Temple to search for cure for his disease. He had a spiritual encounter with the young Buddha, Munsubosal, and afterwards found himself miraculously cured. Another legend tells of a tree that was awarded the rank of 'Imperial Minister' after it bowed to Sejo when he was journeying to Beopjusa in search of healing and peace of mind.

Sejo did a great deal to support Taoism and Buddhism, which had been strongly suppressed in the several decades since the establishment of the Joseon Dynasty. He sponsored the construction of Wolgaksa Temple and created Gangyeongdogam, a government agency for publishing Buddhist texts. He is also credited with expanding and renovating the storage hall for the Tripitaka Koreana at Haeinsa in 1457, and had fifty copies of the Tripitaka printed for distribution.

He restructured the military system, stationing large military garrisons in each province. Just like Taejong, he was a hardliner with regards to foreign policy, attacking Jurchens on the northern front in 1460 (오랑캐/兀良哈) and 1467 (호리개/胡里改). He executed scholars from King Sejong's era for plotting against him, but encouraged publishing, including several history, economics, agricultural, and religious books. Most importantly, he compiled the Kyungguk Taejon, 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.

Passing on the throne

Sejo's oldest son, Crown Prince Euigyung (later named Deokjong) had died in 1457, leaving behind two sons. When Sejo's health began to decline in 1468, at age 52, he turned over the throne to his second son, Grand Prince Haeyang, who became King Yejong, Joseon's 8th monarch, only to die 14 months later. Yejong was only 14 when he took the throne, and his mother, Queen Jeonghee served as regent, the first female regent in the Joseon dynasty. Yejong was succeeded by Grand Prince Deokjong's son, Yi Hyeol who became King Seongjong, Joseon's 9th monarch. Seongjong was still young when he ascended the throne, so Queen Jeonghee, his grandmother, continued as regent for another seven years, until he came of age. Seongjong's reign continued for 25 years, and was marked by prosperity. Seongjong's father was posthumously awarded the title King Deokjong even though he never held the throne.


  • Queen Jeonghee of the Yun Clan (정희왕후 윤씨, 貞喜王后)
    • Crown Prince Euigyung (died before ascending the throne) (의경세자, 懿敬世子)
    • Grand Prince Haeyang (해양대군, 海陽大君), later King Yejong (예종)
    • Princess Euisuk (의숙공주, 懿淑公主)
  • Royal Noble Consort Keun from the Pak clan (근빈 박씨, 謹嬪)
    • Prince Deokwon (덕원군, 德源君)
    • Prince Changwon (창원군, 昌原君)

Preceded by:
Danjong of Joseon
Emperor of Korea
(Joseon Dynasty)
Succeeded by:
Yejong of Joseon

See also

ISBN links support NWE through referral fees

  • Sejo. 1973. Sŏkpo sangjŏl: che 6, 9, 13, 19, 23-24. Sŏul: Taejegak. OCLC: 26563522
  • Sejo, and Yŏng-kyu Min. 1956. Wŏrin sŏkpo. Kukko chʻonggan, che 5-. Sŏul: Yŏnse TAehakkyo Tongbanghak Yŏnʼguso. OCLC: 40392499
  • Yi, Pŏm-nyŏl, and Tong-in Kim. 1982. Sejo Wang Chŏnghŭi Wangbi. Sŏul: Chungang. OCLC: 15408984

External Links

All links retrieved April 18, 2018.

Monarchs of Joseon and The Korean Empire
Joseon: Emperor Taejo | King Jeongjong | King Taejong | King Sejong the Great | King Munjong | King Danjong
King Sejo | King Yejong | King Seongjong | Yeonsangun | King Jungjong | King Injong | King Myeongjong
King Seonjo | Gwanghaegun | King Injo | King Hyojong | King Hyeonjong | King Sukjong
King Gyeongjong | King Yeongjo | King Jeongjo | King Sunjo | King Heonjong | King Cheoljong

Korean Empire: Emperor Gojong | Emperor Sunjong


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