Sejong the Great

**Sejong** (; 15 May 1397 – 30 March 1450), personal name **Yi To** (), commonly known as **Sejong the Great** (), was the fourth monarch of the Joseon dynasty of Korea. He is regarded as one of the greatest rulers in Korean history, and is remembered as the inventor of Hangul, the native alphabet of the Korean language.

He is one of only two Korean kings called "great" (the other is Gwanggaeto the Great of Goguryeo). He picked out young scholars and tried to fix the prejudice of classes by helping intelligent but low-class prodigies. In 1442, he had Jang Yeongsil, a scientist in Joseon, invent the _Cheugugi_ (). This was a kind of tool to help measure the rain and how much it fell. Also, he expanded the territory of Joseon.

One of the best works and the biggest reason why Sejong was called great was because he created the _Hunminjeongeum_ (). It is called in modern days as Hangul (). Because of the creation of the _Hunminjeongeum_, Joseon (now Korea) now got its own alphabet, and many people, most of whom have never learned how to read Hanja (Chinese characters used for Korean) could learn how to read and write much more easily than before.

## Early life

Sejong was the third son of King Taejong. When he was twelve, he became grand prince and married Shim On of Cheongsong. When he was young, he was very good at studying. His father liked him more than his other brothers.

His older brothers, Yangnyeong and Hyoryeong, thought they were not fit to be king and that it was their duty to make Sejong the king, even though he was younger than them. So they acted rudely and badly in front of the court and were soon banished.

Yangnyeong became a traveler who wandered in the mountains, and Hyoryeong became a Buddhist monk. This later became a heartfelt and traditional legend in South Korea.

## Reign (1418–1450)

In 1418, Sejong replaced his eldest brother, Yi Je, as crown prince; a few months later, Taejong voluntarily abdicated the throne in Sejong's favor.

In the early years of Sejong's reign, King Emeritus Taejong retained vast powers, most notably military power, and continued to govern until his death in 1422.

Sejong reinforced Korean Confucian and Neo-Confucian policies, and enacted major legal amendments ().

He personally created and promulgated the Korean alphabet, encouraged advancements in science and technology, and introduced measures to stimulate economic growth. He launched military campaigns to the north and implemented a relocation policy (), establishing settlements in the newly conquered areas.

To the south, he ordered the Ōei invasion of Tsushima to repel and subjugate the Japanese pirates, but the campaign was unsuccessful.

From 1439, he became increasingly ill and his eldest son, Crown Prince Yi Hyang, acted as regent. Sejong died on March 1450.

## Related pages

- Hunminjeongeum
- Cheugugi
- Yeonsangun of Joseon

## Infobox (royalty)

- **name**: Sejong the Great

- **image**: King Sejong the Great.jpg
- **caption**: Posthumous portrait, 1973
- **succession**: King of Joseon
- **reign**: 9 September 1418 – 30 March 1450
- **reign-type**: Reign
- **coronation**: Geunjeongjeon Hall, Gyeongbok Palace, Seoul, Hanseong
- **cor-type**: Enthronement
- **predecessor**: Taejong of Joseon, Taejong
- **regent**: Crown Prince Yi Hyang (1439–1450)
- **successor**: Munjong
- **birth name**: Yi To
- **birth place**: Junsu-bang, Seoul, Hanseong, Joseon
- **death place**: Grand Prince Yeongeung's Mansion, Seoul, Hanseong, Joseon
- **burial place**: w:Royal Tombs of the Joseon dynasty#Yeongneung (영릉), Yeongneung Mausoleum, Yeoju, Gyeonggi Province, South Korea
- **spouse-type**: Spouse(s)
- **issue-link**: #Family
- **issue-pipe**: among others...
- **full name**: Yi To ()
- **era dates**: 1450
- **posthumous name**: * Joseon: Great King Jangheon with Cultured Sagacity, Martial Wisdom, Excellent Benevolence,and Brilliant Filial Piety ()
* Ming dynasty: Jangheon ()
- **temple name**: Sejong ()
- **house**: w:Jeonju Yi clan, Jeonju Yi
- **house-type**: Clan
- **father**: Taejong of Joseon
- **mother**: Queen Wongyeong
- **religion**: Korean Confucianism (Neo-Confucianism) → Korean Buddhism
- **succession1**: Crown Prince of Joseon
- **reign-type1**: Tenure
- **reign1**: 8 July 1418 – 9 September 1418
- **predecessor1**: Crown Prince Yi Je
- **successor1**: Crown Prince Yi Hyang
- **dynasty**: Yi dynasty