Sejong the Great

Sejong (15 May 1397 – 30 March 1450), personal name Yi Do, 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.

Initially titled Grand Prince Chungnyeong, he was the third son of King Taejong and Queen Wongyeong. 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 (future King Munjong), acted as regent.

Early life
Sejong was born Yi Do on 15 May 1397, in Junsubang, Hanseong (Seoul), Joseon to father Yi Bang-won (the future King Taejong) and a lady of the influential Yeoheung Min clan (later Queen Wongyeong).

There is reportedly little known information about Yi's childhood. Historian Lee Han argues that contemporary chroniclers had little reason to find Yi interesting at the time of his birth; he was the third son of the fifth son of the Joseon founding monarch Taejo, and his father was then not the heir to the throne. Yi was born outside of the palace Gyeongbokgung.

Yi's father was reportedly calculating and relentless in his pursuit of power. He tactically assassinated his rivals, amongst whom were his brothers and members of his wife's clan. Amidst a violent feud with politician Jeong Do-jeon, the Yi couple sent their two older sons away, and kept only Yi Do near. He was reportedly well loved by his parents.

During their rise to power, Yi's mother was reportedly fiercely devoted to her husband. She was reportedly similarly sharp, and conspired with him. When her husband became the third king of Joseon in 1400 and began taking concubines, she was heartbroken and jealous, and their relationship deteriorated thereafter. She then focused on raising her own children. Taejong openly disliked in-laws and their ability to gain political influence. Eventually, he used his wife's jealousy as a pretext to quash her and her family's influence in the court. In spite of his father's pushback, Yi Do was reportedly devoted to his mother: caring for her in times of illness, and mourning for her upon her death.

In 1408, his father arranged for him to marry a girl, two years his senior, of the Cheongsong Sim clan: the future Queen Soheon. In 1412, Yi Do was given the title of Grand Prince Chungnyeong. In 1414, he had his first son, the future King Munjong.

Selection as heir to the throne
Via primogeniture, Taejong's eldest son, Grand Prince Yangnyeong, was originally supposed to inherit the throne. However, Taejong and various government officials increasingly felt over time that Yangnyeong was unsuitable for the role, because he behaved in ways that they deemed erratic and irresponsible.

In mid-1418, government officials petitioned Taejong to consider a new candidate for the throne. Following primogeniture, Taejong initially considered Yangnyeong's eldest son for the role. However, the officials objected to this, and insisted that King Taejong should select a wise person as heir apparent. Hesitant to break primogeniture once again, King Taejong asked the officials to propose an alternative. They reportedly gave an indirect response: "the father knows his sons best, as the king knows his subjects best". Taejong judged his second son, Grand Prince Hyoryeong, to have a disposition too soft for the role. He then proposed Chungnyeong, whom he felt was intelligent and sharp in matters of politics. This decision was reportedly welcomed by the petitioners, who confirmed that Chungnyeong had been their preferred choice. On 8 July 1418, Chungnyeong was made crown prince of Joseon.

Reign
On 9 September 1418, Chungnyeong succeeded the throne as King Sejong, upon the abdication of Taejong. However, Taejong openly continued to hold onto military power, and functionally continued to make the major political decisions. This would continue until Taejong's death in 1422. Sejong reportedly consistently deferred to his father during this period. Their dual role reportedly caused some confusion in this court. When Queen Soheon's father, Shim On, criticized the system, Taejong used the criticism as a pretext to charge Shim with treason and execute him. Other members of the queen's family were exiled or made commoners, which left her politically isolated and unable to protest. She spent much of her time in the palace, caring for her children.

Sejong inherited a throne with expanded political power, due to the efforts of his father. In spite of his power, he was reportedly light on free speech, and encouraged the meritocratic elevation of scholars who passed the gwageo, the national civil service exams.

Religion
During the Goryeo period, monks wielded a strong influence in politics and the economy. With the dominant powers of Joseon now being devout Confucianists, Buddhism was considered a false philosophy and the monks were viewed as corrupted by power and money.

Likewise, Sejong continued Joseon's policies of "worshipping Confucianism and oppressing Buddhism". He suppressed Buddhism by banning outside monks from entering Hanseong and reduced the seven schools of Buddhism down to two, Seon and Gyo, drastically decreasing the power and wealth of the religious leaders. One of the key factors in this suppression was Sejong's reform of the land system. This policy resulted in temple lands being seized and redistributed for development, with the monks losing large amounts of economic influence. Furthermore, he performed government ceremonies according to Confucianism, and encouraged people to behave according to the teachings of Confucius.

At the same time, Sejong sought to alleviate religious tensions between Confucianism and Buddhism. The Seokbosangjeol, a 24-volume Korean-language translation of Chinese Buddhist texts (a biography of Buddha and some of his sermons), was commissioned and published in Sejong's reign by Grand Prince Suyang, as an act of mourning for Queen Soheon. Sejong advocated the project despite fierce opposition from his courtiers, and expressed his disapproval for those who enjoy the ideals of Buddhism, yet scold others for being the same.

In 1427, Sejong also gave a decree against the Huihui (Korean Muslim) community that had held special status and stipends since Yuan dynasty's rule over Goryeo. The Huihui were forced to abandon their headgear, to close down their "ceremonial hall" (a mosque in the city of Gaegyeong, in present-day Kaesong) and worship like everyone else. No further mention of Muslims exist during the Joseon era.

Economy
In the early years of the Joseon dynasty, the economy was based on a barter system with cloth, grain, and cotton being the most common forms of currency. In 1423, under King Sejong’s administration, the government attempted to develop a national currency modeled off of the Tang dynasty's kaiyuan tongbao. The Joseon tongbo was a bronze coin, backed by a silver standard, with 150 coins being equal to 600 grams of silver. Production of the Joseon Tongbo ceased in 1425 because they were too expensive to make, with the exchange rate falling to less than the intrinsic value of the coin.

Military
King Sejong was an effective military planner. He created various military regulations to strengthen the safety of his kingdom, and supported the advancement of military technology, including cannon development. Different kinds of mortars and fire arrows were tested as well as the use of gunpowder.

In June 1419, under the advice and guidance of his father, Sejong embarked upon the Ōei Invasion. The ultimate goal of this military expedition was to remove the nuisance of Japanese pirates who had been operating close to Tsushima Island. During the invasion, 245 Japanese were killed, and another 110 were captured in combat, while 180 Korean soldiers died. More than 150 kidnap victims (146 Chinese and 8 Koreans) were also liberated. A truce was made in July 1419 and the Joseon army returned to the Korean Peninsula, but no official documents were signed until 1443. In this agreement, known as the Treaty of Gyehae, the daimyo of Tsushima promised to pay tribute to the king of Joseon, and in return, the Joseon court rewarded the Sō clan with preferential rights regarding trade between the two countries.

In 1433, Sejong sent Kim Jong-seo, a prominent general, to the north to destroy the Jurchens (later known as the Manchus). Kim's military campaign captured several fortresses, pushed north, and expanded Korean territory, to the Songhua River.

Science, technology, and agriculture


In 1420, Sejong's love for science led him to create an institute within Gyeongbokgung known as the Hall of Worthies. The institute was responsible for conducting scientific research with the purpose of advancing the country's technology. The Hall of Worthies was meant to be a collection of Joseon's best and brightest thinkers, with the government offering grants and scholarships to encourage young scholars to attend.

Sejong promoted the sciences. He wanted to help farmers so he decided to compile a farmer's handbook. Published in 1429, the book – Nongsa Jikseol – dealt with planting, harvesting and soil treatment, and contained information about the different farming techniques that were gathered by scientists from different regions of Korea. These techniques were needed in order to maintain the newly adopted methods of intensive and continuous cultivation.

One of his close associates was the great inventor Jang Yeong-sil. As a young person, Jang was a naturally creative and smart thinker. Sejong noticed his skill and immediately called him to his court in Hanseong. Upon giving Jang a government position and funding for his inventions, officials protested, believing a person from the lower classes should not rise to power among nobles. Sejong instead believed he merited support because of his ability. Jang Yeong-sil created new significant designs for water clocks, armillary spheres, and sundials.

In 1442, Jang Yeong-sil made one of the world's first standardized rain gauges named cheugugi . This model has not survived, with the oldest existing Korean rain gauge being made in 1770, during the reign of King Yeongjo. According to the Daily Records of the Royal Secretariat, Yeongjo wanted to revive the glorious times of Sejong the Great, and started reading chronicles from that era. When he came across the mention of a rain gauge, Yeongjo ordered a reproduction. Since there is a mark of the Qing dynasty ruler Qianlong (r. 1735–96), dated 1770, this Korean-designed rain gauge is sometimes misunderstood as having been imported from China.

In 1434, Jang Yeong-sil, tasked by King Sejong, invented the gabinja, a new type of printing press. This printing press was said to be twice as fast as the previous model and was composed of copper-zinc and lead-tin alloys. Sejong also wanted to reform the Korean calendar system, which was at the time based upon the longitude of the Chinese capital. He had his astronomers create a calendar with the Joseon capital of Hanseong as the primary meridian. This new system allowed Joseon astronomers to accurately predict the timing of solar and lunar eclipses.

In the realm of traditional Korean medicine, two important treatises were written during his reign. These were the Hyangyak Jipseongbang and the Euibang Yuchwi, which historian Kim Yong-sik says represents "the Koreans' efforts to develop their own system of medical knowledge, distinct from that of China".

Public welfare
In 1426, Sejong enacted a law that granted government slaves women 100 days of maternity leave after childbirth, which, in 1430, was lengthened by one month before childbirth. In 1434, he also granted the husbands 30 days of paternity leave.

In order to provide equality and fairness in taxation for the common people, Sejong issued a royal decree to administer a nationwide public opinion poll regarding a new tax system called Gongbeop in 1430. Over the course of five months, the poll surveyed 172,806 people, of which approximately 57% responded with approval for the proposed reform.

Joseon's economy depended on the agricultural output of the farmers, so Sejong allowed them to pay more or less tax according to the fluctuations of economic prosperity and hard times. Because of this, farmers could worry less about tax quotas and instead work at maintaining and selling their crops.

It is said that once, when the palace had a significant surplus of food, the king distributed it to poor peasants who needed it.

Literature
Sejong composed the famous Yongbieocheonga ("Songs of Flying Dragons"; 1445), Seokbo Sangjeol ("Episodes from the Life of Buddha"; July 1447), Worin Cheongang Jigok ("Songs of the Moon Shining on a Thousand Rivers"; July 1447), and Dongguk Jeongun ("Dictionary of Proper Sino-Korean Pronunciation"; September 1447).

Arts
One of Sejong’s closest friends and mentors was the 15th century musician Bak Yeon. Together they composed over two hundred musical arrangements. Sejong’s independent musical compositions include the Chongdaeop ('Great Achievements'), Potaepyeong ('Preservation of Peace'), Pongnaeui ('Phoenix'), and Yominrak ('A Joy to Share with the People'). Yominrak continues to be a standard piece played by modern traditional Korean orchestras, while Chongdaeop and Potaepyeong are played during the Jongmyo Jerye (memorials honoring the kings of Joseon).

In 1418, during Sejong's reign, scholars developed the Pyeongyeong, a lithophone modeled off of the Chinese bianqing. The Pyeongyeong is a percussion instrument consisting of two rows of 8 pumice slabs hung on a decorative wooden frame with a 16-tone range and struck with an ox horn mallet. It was manufactured using pumice mined from the Gyeonggi Province and was primarily used for ceremonies.

Sejong's contribution to the arts continued long after his death; he had always wanted to use Korean music rather than Chinese music for ancestral rituals, but conservative court officials stopped his efforts. However, when Sejong's son, King Sejo, rose to the throne, he modified the ritual music composed by his father and created the 'Jongmyo court music', which was used for royal ancestral rituals and is now inscribed as an UNESCO Intangible Cultural Hertiage.

Hangul


King Sejong profoundly affected Korea's history with the creation and introduction of hangul, the native phonetic writing system for the Korean language. Although it is widely assumed that he ordered the Hall of Worthies to invent the script, contemporaneous records such as the Veritable Records of King Sejong and Jeong In-ji's preface to the Hunminjeongeum Haerye emphasize that Sejong invented it himself.

Before the creation of the new alphabet, the people of Joseon primarily used Classical Chinese to write, alongside a few writing systems like idu, hyangchal, gugyeol, and gakpil—which used Chinese characters to approximate sounds of the Korean language—that had been in use since hundreds of years before hangul. However, due to the fundamental differences between the Korean and Chinese languages, and the large number of Chinese characters required, lower-class people of Joseon lacked the privilege of education and were illiterate. To promote literacy, King Sejong created hangul (which initially had 28 letters, four of which are no longer in use).

Hangul was completed in 1443 and published in 1446 along with a 33-page manual titled Hunminjeongeum, explaining what the letters are as well as the philosophical theories and motives behind them.

King Sejong faced backlash from the noble class as many disapproved of the idea of a common writing system, with some openly opposing its creation. Many within the nobility believed that giving the peasants the ability to read and write would allow them to find and abuse loopholes within the law. Others felt that hangul would threaten their families’ positions in court by creating a larger pool of civil servants. The Joseon elite continued to use the Chinese hanja long after Sejong’s death. Hangul was often treated with contempt by those in power and received criticism in the form of nicknames, including eonmun ("vulgar script"), amkeul ("women’s script"), and ahaekkeul ("children’s script"). Despite this, the system gained popularity among women and fiction writers.

In 1504, the study and publication of hangul was banned by Yeonsangun. Its spread and preservation can be largely attributed to three main factors: books published for women, its use by Buddhist monks, and the introduction of Christianity in Korea in 1602. Hangul was brought into the mainstream culture in the 16th century, due to a renaissance in literature and poetry. It continued to gain popularity well into the 17th century, and gained wider use after a period of nationalism in the 19th century. In 1849, it was adopted as Korea’s national writing system, and saw its first use in official government documents. After the Treaty of 1910, hangul was outlawed again until the liberation of Korea in 1945.

Health issues and death


Sejong suffered from eye diseases and deteriorating vision and likely had health issues linked to excessive meat consumption all throughout his life. Sejong's love for meat is clear from a comment by King Emeritus Taejong. When Sejong stopped eating fish and meat to mourn after the death of Jeongjong—Sejong's uncle and Taejong's older brother—Taejong remarked that Sejong had always found it hard to eat without meat since he was a child. Sejong also started having musculoskeletal pain at the age of 22. One day he was supposed to organize a farewell party for the emissaries to the Ming dynasty but was in too much pain to do so. Sejong said: "My waist and back are stiff and immobile, so it is hard to bend or straighten." There is speculation that he had diabetes, but there is inadequate evidence for a modern medical diagnosis. There is also an account of Sejong's having a disease that roughly translates to palsy and essential tremor, but terminology of the 15th century Korean traditional medicine does not translate well.

Sejong died on April 8, 1450, on the Gregorian calendar, at the residence of Grand Prince Young-eung at the age of 52. He was buried at Yeongneung, in the same mound as his wife, Queen Soheon, who died four years earlier. The tomb is located in Yeoju, Gyeonggi Province, South Korea.

His successor was his first son, Yi Hyang (posthumously King Munjong). Sejong was concerned that sickly Munjong would die early and leave his vulnerable young son to reign, so he asked scholars from the Hall of Worthies to look after his young grandson, Danjong. As predicted, Munjong died two years after his ascension, and the political stability enjoyed in the past decades disintegrated when Danjong became the sixth king of Joseon at the age of twelve. Eventually, Sejong's second son, Grand Prince Suyang (later known as King Sejo), usurped the throne in 1455. When six court officials were implicated in a plot to restore his nephew, Sejo abolished the Hall of Worthies and executed Danjong along with several ministers who served during Sejong's reign.

Reception and Legacy
Sejong the Great is considered one of the most influential monarchs in Korean history, with the creation of Hangul considered his greatest legacy. Sejong is widely renowned in modern-day South Korea. In a 2024 survey by Gallup Korea, Sejong was nominated as the second most respected figure by South Koreans, only to be surpassed by Yi Sun-sin. The Encyclopedia of Korean Culture evaluates the reign of Sejong "the most shining period of the history of our [the Korean] people." Sejong's creation of the Korean alphabet is celebrated every 9th of October as Hangul Day, a national holiday.

Multiple places in South Korea, including Sejong Street (Sejongno; 세종로, 世宗路), Sejong–Pocheon Expressway, and Sejong Special Autonomous City, South Korea's de facto administrative capital, are named after him. Various institutes such as King Sejong Station, the King Sejong Institute, the Sejong Center for the Performing Arts, Sejong Science High School, and Sejong University also bear his name. A 9.5 m bronze statue of King Sejong, unveiled in 2009 in celebration of the 563rd anniversary of the invention of the Korean alphabet, now sits on a concrete pedestal on the boulevard of Gwanghwamun Square and directly in front of the Sejong Center for the Performing Arts in Seoul. The pedestal contains one of the several entrances to the 3,200 m2 underground museum exhibit entitled "The Story of King Sejong". In 2007, the South Korean Chief of Naval Operations officially announced the naming of its Sejong the Great-class destroyers, further explaining that Sejong's name was chosen as he was the most beloved figure among South Koreans.

A portrait of Sejong is featured on the 10,000 won banknote of the South Korean won, along with various scientific tools invented under his reign. Sejong was first portrayed in the 1000-hwan bill as part of the August 15, 1960 currency reform, replacing the portrait of former president Syngman Rhee. Sejong was also featured on the 500-hwan bill the following year. Both bills were decommissioned in 1962. Sejong's portrait returned with the introduction of the 10,000-won bill, when his portrait and Geunjeongjeon replaced Seokguram and Bulguksa as features of the bill, in 1973.

In North Korea, Sejong is not as widely commemorated compared to the South. Vol. 16 of the Great Korean Encyclopedia asserts that "feudalist pressure and extortion" was strengthened during Sejong's reign, and that all of Sejong's policies were directed for the "benefit of the feudalist ruling class". Contrastingly, in a column from its December 15, 2001 issue, North Korean news outlet Tongil Sinbo reported that Sejong the Great greatly contributed to Korean science during his reign of 30 years. Hangul Day is also celebrated in North Korea, albeit on a different date.

Family
Sejong and his primary consort Soheon had ten children together: the most for any queen consort of the Joseon period. Historian Lee Han argues it is unclear if their relationship had genuine love; while they had numerous children together, and there is evidence of the two caring for and treating each other respectfully, Taejong had the queen's father executed, and Sejong dutifully consented to this. Consort(s) and their respective issue
 * Father: King Taejong of Joseon (16 May 1367 – 10 May 1422)
 * Grandfather: King Taejo of Joseon (11 October 1335 – 24 May 1408)
 * Grandmother: Queen Sinui of the Cheongju Han clan (4 September 1337 – 23 September 1391)
 * Mother: Queen Wongyeong of the Yeoheung Min clan (11 July 1365 – 10 July 1420)
 * Grandfather: Min Je, Internal Prince Yeoheung (1339–1408)
 * Grandmother: Lady Song of the Yeosan Song clan, Grand Princess Consort of Samhan State (1342–1424)
 * Queen Soheon of the Cheongsong Shim clan (28 September 1395 – 24 March 1446)
 * Princess Jeongso (1412 – 25 February 1424), first daughter
 * Crown Prince Yi Hyang (3 October 1414 – 14 May 1452), first son
 * Princess Jeongui (12 July 1415 – 11 February 1477), second daughter
 * Yi Yu, Grand Prince Suyang (29 September 1417 – 8 September 1468), second son
 * Yi Yong, Grand Prince Anpyeong (19 September 1418 – 18 October 1453), third son
 * Yi Gu, Grand Prince Imyeong (6 January 1420 – 21 January 1469), fourth son
 * Yi Yeo, Grand Prince Gwangpyeong (2 May 1425 – 7 December 1444), fifth son
 * Yi Yu, Grand Prince Geumseong (28 March 1426 – 21 October 1457), seventh son
 * Yi Im, Grand Prince Pyeongwon (18 November 1427 – 16 January 1445), ninth son
 * Yi Yeom, Grand Prince Yeongeung (15 April 1434 – 2 February 1467), fifteenth son
 * Royal Noble Consort Shin of the Cheongju Gim clan (1406 – 4 September 1464)
 * Fourth daughter (? – 1426)
 * Yi Jeung, Prince Gyeyang (12 August 1427 – 16 August 1464), eighth son
 * Yi Gong, Prince Uichang (1428 – 27 February 1460), tenth son
 * Fifth daughter (? – 1429)
 * Yi Chim, Prince Milseong (1430 – 1 January 1479), twelfth son
 * Yi Yeon, Prince Ikhyeon (1431 – 4 May 1463), fourteenth son
 * Yi Jang, Prince Yeonghae (20 March 1435 – 5 May 1477), seventeenth son
 * Yi Geo, Prince Damyang (8 January 1439 – 10 March 1450), eighteenth son
 * Royal Noble Consort Hye of the Cheongju Yang clan (? – 9 November 1455)
 * Yi Eo, Prince Hannam (8 September 1429 – 29 May 1459), eleventh son
 * Yi Hyeon, Prince Suchun (13 July 1431 – 5 June 1455), thirteenth son
 * Yi Jeon, Prince Yeongpung (17 August 1434 – 20 June 1456), sixteenth son
 * Royal Noble Consort Yeong of the Jinju Gang clan (? – 20 January 1483)
 * Yi Yeong, Prince Hwaui (5 September 1425 – after 1489), sixth son.
 * Royal Consort Gwi-in of the Miryang Park clan
 * Royal Consort Gwi-in of the Jeonju Choe clan
 * Royal Consort Sug-ui of the Jo clan
 * Royal Consort So-yong of the Hong clan (? – 4 February 1452)
 * Royal Consort Sug-won of the Yi clan
 * Princess Jeongan (1441 – 16 October 1461), seventh daughter
 * Court Lady Song (1396 – 21 August 1463)
 * Princess Jeonghyeon (1425 – 6 November 1480), third daughter
 * Court Lady Cha (? – 1444)
 * Sixth daughter (1430 – 1431)
 * Unknown
 * Yi Dang (1442 – ?), nineteenth son

Television series and films
His life was depicted in the KBS historical drama The Great King, Sejong in 2008.

Video games

 * Sejong is the leader of the Korean civilization in Sid Meier's Civilization VI’s Leader Pass DLC, Sid Meier's Civilization V, and Civilization Revolution 2.
 * Sejong is the starting ruler of Korea in Europa Universalis IV.