King Gyeongjong, previously known as Crown Prince Hwiseo (Hanja: 景宗王 [輝瑞世子]; Born: 20 November 1688 – Died: 11 October 1724, reigned 1720–1724), born Yi Yoon (이윤/李昀) was the 20th king of the Joseon Dynasty. He was the son of King Sukjong and Royal Noble Consort Hui of the Indong Jang clan a.k.a Jang Ok-jeong.
In 1690, Gyeongjong's designation as heir to the throne precipitated a struggle between the Noron and the Soron political factions, which supported King Gyeongjong. Following the death of King Sukjong in 1720, Royal Prince Successor Hwiso (Yi Yun, 이윤 왕세자) ascends the throne at age 33 as King Gyeongjong. He supposedly told Yi I-myeong to name Prince Yeon-ing as Gyeongjong's heir, but suspicions arose between Soron, Noron enemies, from the absence of a historiographer or recorder.
Gyeongjong suffered from ill health during his reign, and the Noron political faction pressured Gyeongjong to step down in favor of his half-brother, Prince Yeon-ing. In 1720, two months after his enthronement, his half brother, Prince Yeon-ing Yi Geum (the future King Yeongjo) was installed as Royal Prince Successor Brother (wangseje/왕세제/王世弟) to handle state affairs, since the king weak health made impossible for him to manage politics.
Gyeongjong's mother, Lady Jang is to blame for his illnesses. She was sentenced to death by poison, in 1701. Following the ruling, Lady Jang begged to see her son, the Crown Prince (later Gyeongjong). As she dashed towards him to greet him, she inflicted a severe injury to the Crown Prince's lower abdomen that left him sterile and unable to produce an heir. Due to King Gyeongjong’s fragile health, he had no energy or time to do anything significant in the four years of his reign.
This aggravated the power struggle and led to a big massacre, namely the Shin-im Literati Purge (辛壬士禍). The Norons sent memorials to the king to no effect while the Sorons used this to their advantage—claiming the Noron faction were trying to usurp power and subsequently getting their rival faction removed from several offices. Members of the Soron faction then came up with an idea to assassinate the heir (Prince Yeon-ing) under the cover of hunting for a white fox said to be haunting the palace, but Queen Dowager Inwon protected him and he was able to keep living, after this he said to the king he rather would go and live as a commoner.
During his four years reign, there were two major incidents of massacre; one is Sinchuk Treachery (辛丑獄事) in which the ruling political party, Soron, swept the opposition Noron, a group that insisted that Gyeongjong's half-brother, Prince Yeon-ing, handle national affairs on behalf of the weak and ailing king during the first year of Gyeongjong reign 1720 and the other one is Im-in Treachery (壬寅獄事) which took place in the 2nd year of his reign, circa 1722. History calls both incidents as Shin-im Literati Purge. During his reign, he made small guns in imitation of the western weapons and reformed the land measurement system in the southern parts of the country.
King Gyeongjong died in 1724 and entombed at the foot of Mount Cheonjang, which is called as the Royal Tomb of Uireung (懿陵) in 146-37 Hwarang Avenue 32nd Street/Hwarangno 32-gil, Seokgwan-dong san 1-5 beonji, Seoul Seongbuk-gu. He was posthumously known as King Gyeongjong Deongmun Ingmu Sun-in Seonhyo the Great (경종덕문익무순인선효대왕/景宗德文翼武純仁宣孝大王).
There was some speculation from Soron party members that his half-brother, Prince Yeon-ing, had something to do with his death due to the earlier attempt by the Noron faction to have him replace Gyeongjong on the throne, but several historiographers now conclude that he could have died of eating spoiled seafood, as described in Homer's book, The History of Korea. “But we may well doubt the truth of the rumour, for nothing that is told of that brother indicates that he would commit such an act, and in the second place a man who will eat shrimps in mid-summer, that have been brought thirty miles from the sea without ice might expect to die.”
After his death, the chronicles of Gyeongjong's rule were published in 1732 under the reign of King Yeongjo. A few of Gyeongjong's youthful calligraphic works have also survived.