Sejong the Great

 
Sejong the Great (; 15 May 1397 – 8 April 1450) was the fourth king of the Joseon dynasty of Korea. He was the third son of King Taejong and Queen Wongyeong. Sejong was designated as Crown Prince after his older brother Prince Yangnyeong was stripped of his title. He ascended to the throne in 1418. During the first four years of Sejong's reign, Taejong governed as regent and executed Sejong's father-in-law, Sim On, and his close associates.
Sejong reinforced Korean Confucian and Neo-Confucian policies, and enacted major legal amendments (; ). He personally created and promulgated the Korean alphabet Hangul, encouraged advancements of science and technology, and introduced measures to stimulate economic growth. He dispatched military campaigns to the north and instituted the policy (; ) to attract new settlers to the region. To the south, he helped subjugate Japanese pirates, and in the Ōei Invasion capture Tsushima Island (also known as Daema Island in the Korean language).
During his reign from 1418 to 1450, Sejong governed along with Taejong from 1418 to 1422. He then governed as the sole monarch from 1422 to 1450, although after 1439 he became increasingly ill, and beginning in 1442, his son, Crown Prince Munjong, acted as regent for him.
Name.
Although the appellation "the Great" (；) was given posthumously to almost every ruler of Goryeo and Joseon, this title is usually associated with Gwanggaeto and Sejong.
Early life.
Sejong was born on 15 May 1397, the third son of King Taejong. When he was twelve, he became Grand Prince Chungnyeong (충녕대군). As a young prince, Sejong was favored by King Taejong over his two older brothers.
As the third son of Taejong, Sejong's ascension to the throne was unique. Taejong's eldest son, Yangnyeong (), was named heir apparent in 1404. However, Yangnyeong's free spirited nature as well as his preference for hunting and leisure activities resulted in his removal from the position of heir apparent in June 1418. Though it is said that Yangnyeong abdicated in favor of his younger brother, there are no definitive records regarding Yangnyeong's removal. Taejong's second son Grand Prince Hyoryeong became a monk upon the elevation of his younger brother Sejong.
Following the removal of Yangnyeong as heir apparent, Taejong moved quickly to secure his youngest son's position as heir apparent. The government was purged of officials who disagreed with the removal of Yangnyeong. In August 1418, Taejong abdicated in favour of Sejong. However, even in retirement Taejong continued to influence government policy. Sejong's surprising political skill and creativity did not become apparent until after Taejong's death in 1422.
While making Hangeul, Sejong slowly lost his sight. However, King Sejong continued to study and create Hangeul, and until shortly before his death, he devoted himself to Hangul and passed away.
Governance.
Religion.
King Sejong reorganized the Korean government by appointing people from different social classes as civil servants. Furthermore, he performed official government events according to Confucianism, and he encouraged people to behave according to the teachings of Confucianism. As a result, Confucianism became the social norm of Korea at the time.
He suppressed Buddhism by banning outside Buddhist monks from entering Seoul and reduced the seven schools of Buddhism down to two, Seon and Gyo, drastically reducing the power and wealth of the Buddhist hierarchy.
In 1427, Sejong also ordered a decree against the Huihui (Korean Muslim) community that had had special status and stipends since the Yuan dynasty. The Huihui were forced to abandon their headgear, to close down their "ceremonial hall" (Mosque in the city of Kaesong) and worship like everyone else. No further mention of Muslims exist during the era of the Joseon.
Foreign policy.
He collaborated closely with the Chinese Ming Dynasty. In relationship with Jurchen people, he installed 10 military posts, 4 counties and 6 garrisons (hangul: 사군육진 hanja: 四郡六鎭), in the northern part of the Korean Peninsula.
He opened three ports to trade with Japan. However, he also launched the Ōei Invasion to crush Japanese pirates (Wokou) in the East China Sea.
Military.
King Sejong was an effective military planner. He created various military regulations to strengthen the safety of his kingdom, supported the advancement of Korean military technology, including cannon development. Different kinds of mortars and fire arrows were tested as well as the use of gunpowder.
In May 1419, King Sejong, under the advice and guidance of his father Taejong, embarked upon the Gihae Eastern Expedition, the ultimate goal of this military expedition to remove the nuisance of Japanese pirates who had been operating out of Tsushima Island. During the expedition, 245 Japanese were killed, and another 110 were captured in combat, while 180 Korean soldiers were killed. 146 Chinese and 8 Korean kidnapped were liberated by this expedition. In September 1419 a truce was made and the Korean army returned to Korea, but the Treaty of Gyehae was signed in 1443, in which the Daimyo of Tsushima promised to pay tribute to the King of Joseon; in return, the Joseon court rewarded the Sō clan with preferential rights regarding trade between Japan and Korea.
In 1433, Sejong sent Kim Jongseo (hangul: 김종서, hanja: 金宗瑞), a prominent general, north to destroy the Jurchens (later known as the Manchus). Kim's military campaign captured several castles, pushed north, and expanded Korean territory, to the Songhua River. 4 counties and 6 garrisons were established to safeguard the people from the Jurchens.
Science, technology, and agriculture.
Sejong promoted the sciences. He wanted to help farmers so he decided to create a farmer's handbook. The book—the Nongsa jikseol (hangul: 농사직설, hanja: 農事直說)—contained information about the different farming techniques that he told scientists to gather in different regions of Korea. These techniques were needed in order to maintain the newly adopted methods of intensive, continuous cultivation in Korean agriculture.
One of his close associates was the great Korean inventor Jang Yeong-sil (hangul: 장영실, hanja: 蔣英實). Jang was naturally a creative and smart thinker as a young person. Sejong noticed Jang's skill and immediately called him to his court in Seoul. 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 Jang merited support because of his ability. Jang created new significant designs for water clocks, armillary spheres, and sundials.
In 1442, Jang made one of the world's first standardized rain gauges named Cheugugi. This model has not survived, since the oldest existing Korean rain gauge is one made in 1770, during the reign period of King Yeongjo. According to the Daily Records of the Royal Secretariat (hangul: 승정원일기；hanja: 承政院日記), King Yeongjo wanted to revive the glorious times of King Sejong the Great, and so read chronicles of Sejong's era. When he came across mention of a rain gauge, King Yeongjo ordered a reproduction. Since there is a mark of the Qing Dynasty ruler Qianlong (r. 1735–1796) of China, dated 1770, this Korean-designed rain gauge is seen as having been imported from China.
Sejong also wanted to reform the Korean calendar system, which was at the time based upon the longitude of the Chinese capital. Sejong had his astronomers create a calendar with the Joseon capital of Seoul as the primary meridian. This new system allowed Korean 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 Yongsik says represents "Koreans' efforts to develop their own system of medical knowledge, distinct from that of China."
Humanitarianism.
In 1426, Sejong the Great enacted a law that granted government "nobi" women 100 days of maternity leave after childbirth, which, in 1430, was lengthened by one month before childbirth. In 1434, Sejong also granted the husbands 30 days of paternity leave.
In order to provide equality and fairness in taxation for the common people, Sejong the Great issued a royal decree to administer a nationwide public opinion poll regarding a new tax system called "Gongbeop" in 1430. Over the course of 5 months, the poll surveyed 172,806 people, of which approximately 57% responded with approval for the proposed reform.
Sejong depended on the agricultural produce of Joseon's farmers, so he allowed them to pay more or less tax according to fluctuations of economic prosperity or hard times. Because of this, farmers could worry less about tax quotas and work instead at surviving and selling their crops. Once the palace had a significant surplus of food, King Sejong then distributed food to poor peasants or farmers who needed it.
Literature.
In 1429 "Nongsa-jikseol" (hangul: 농사직설, hanja: 農事直說, "Explanations of Agriculture") was compiled. It was the first book about Korean farming, dealing with agricultural subjects such as planting, harvesting, and soil treatment.
Most government officials opposed usage of hangul, preferring to continue to use Hanja.
Sejong was also a writer. He composed the famous "Yongbi Eocheon Ga" ("Songs of Flying Dragons", 1445), "Seokbo Sangjeol" ("Episodes from the Life of Buddha", July 1447), "Worin Cheon-gang Jigok" ("Songs of the Moon Shining on a Thousand Rivers", July 1447), and the reference "Dongguk Jeong-un" ("Dictionary of Proper Sino-Korean Pronunciation", September 1447).
In 1420 Sejong established the Hall of Worthies (; ; Jiphyeonjeon) at the Gyeongbokgung Palace. It consisted of scholars selected by the king. The Hall participated in various scholarly endeavors, of which the best known may be the compilation of the "Hunmin Jeongeum".
Hangul.
King Sejong the Great profoundly affected Korean history with his personal creation and introduction of hangul, the native phonetic writing system for the Korean language. Although it is widely assumed that King Sejong ordered the Hall of Worthies to invent Hangul, contemporary records such as the "Veritable Records of King Sejong" and Jeong Inji's preface to the "Hunminjeongeum Haerye" emphasize that he invented it himself.
Before the creation of Hangul, people in Korea (known as Joseon at the time) primarily wrote using Classical Chinese alongside phonetic writing systems based on Chinese script that predated Hangul by hundreds of years, including idu, hyangchal, gugyeol, and gakpil. However, due to the fundamental differences between the Korean and Chinese languages, and the large number of characters that needed to be learned, there was much difficulty in learning how to write using Chinese characters for the lower classes, who often lacked the privilege of education. To assuage this problem, King Sejong created the unique alphabet known as Hangul to promote literacy among the common people. 
King Sejong created the Korean alphabet (which numbered 28 letters at its introduction, of which four letters have become obsolete), with the explicit goal being that Koreans from all classes would read and write. Each consonant letter is based on a simplified diagram of the patterns made by the human speech organs (the mouth, tongue and teeth) when producing the sound related to the character, while vowels were formed by combinations of dots and lines representing heaven (a circular dot), earth (a horizontal line) and humanity (a vertical line). Morphemes are built by writing the characters in syllabic blocks. The blocks of letters are then strung together linearly.
Hangul was completed in 1443 and published in 1446 along with a 33-page manual titled "Hunmin Jeong-eum", explaining what the letters are as well as the philosophical theories and motives behind them. The "Hunmin Jeong-eum" purported that anyone could learn Hangul in a matter of days. People previously unfamiliar with Hangul can typically pronounce Korean script accurately after only a few hours of study.
Death.
Sejong was blinded years later by diabetes complications that eventually took his life in 1450. He was buried at the Yeong Mausoleum (; ). His successor was his first son, Munjong. Sejong judged that his sickly son, Munjong, was unlikely to live long and on his deathbed asked the Hall of Worthies scholars to look after his young grandson, Danjong. As predicted, Munjong died two years after his accession, and political stability enjoyed under Sejong disintegrated when Danjong became the sixth king of Joseon at the age of twelve. Eventually, Sejong's second son, Sejo, usurped the throne from Danjong in 1455. When the six martyred ministers were implicated in a plot to restore Danjong to throne, Sejo abolished the Hall of Worthies, and executed Danjong and several ministers who served during Sejong's reign.
Legacy.
Statue and museum exhibit.
A bronze statue of King Sejong was placed in 2009 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 sculptor was Kim Young-won. The pedestal contains one of several entrances to the 3,200 square meter, underground museum exhibit entitled "The Story of King Sejong". It was dedicated on Hangul Day in celebration of the 563rd anniversary of the invention of the Korean alphabet by King Sejong.
Namesake from Sejong.
The street Sejongno and the Sejong Centre for the Performing Arts, both located in central Seoul, are named after King Sejong.
In early 2007, the Republic of Korea government decided to create a special administrative district from part of the present Chungcheongnam-do Province, near what is presently Daejeon. The district was named Sejong Special Autonomous City.
Portrait in Korean currency.
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.
Depiction in arts and media.
The life of Sejong was depicted in the KBS Korean historical drama "King Sejong the Great" in 2008. Sejong is also depicted in the 2011 SBS drama "Deep Rooted Tree" and 2016 KBS1 drama "Jang Yeong-sil".