Crown Prince Uiso (Korean: 의소세자;Hanja: 懿昭世子; 27 September 1750 – 17 April 1752^[a]) orCrown Prince Successor Uiso (의소세손;懿昭世孫), personal nameYi Jeong (이정;李琔) was aJoseonCrown Prince as the son ofCrown Prince Sado andCrown Princess Consort Hyegyeong and was third in line of succession to the throne toKing Yeongjo. He was the older brother ofKing Jeongjo. His Chinese name wasChangheung (창흥;昌興;Changheung;J'anghŭng).^[1]

His mother,Crown Princess Consort Hye, of the Pungsan Hong clan was the great-great-great-granddaughter fromPrincess Jeongmyeong, the only daughter ofQueen Inmok andKing Seonjo. Due to intermarriage into the royal family, Princess Jeongmyeong was also his 5th great-grandaunt, and 4th great-grandmother.

His maternal grandfather wasHong Bong-han, whose younger brother wasHong In-han, a minister and later Prime Minister of that time.

He was the first grandson of the 21stKing Yeongjo of Joseon and his father,Crown Prince Sado, was the illegitimate second son of King Yeongjo. King Yeongjo's first son,Crown Prince Hyojang, died at the age of 10, leaving Crown Prince Sado as King Yeongjo's only male descendant. King Yeongjo hoped for another son but instead bore only daughters.

Uiso's father Crown Prince Sado had a severe mental illness and was often at odds with his father, King Yeongjo. Crown Prince Sado favoured the political partySoron, while King Yeongjo supported the ruling partyNoron.

On September 27, 1750, he was born in Gyeongchungung,Changgyeonggung,Hanseong, Joseon. On May 13, 1751 KingYeongjo declared him the political heir.

In December 1751, his auntCrown Princess Consort Hyeon died. Soon after on 17 April 1752, Crown Prince Uiso died in Tongmyeongjeon Hall. His grandfather, King Yeongjo took both of their deaths hard and suffered from psychological trauma for some time.

He was given a state funeral,^[2] from special instructions of King Yeongjo. His body was buried to the south of Mt. Ahnhyon (안현 鞍峴),Bugahyeon-dong inHanseong.^[3] King Yeongjo named his graveUiso grave and wrote the epitaphs, erecting a tombstone.

Ten years later, in 1762, his grandfather, King Yeongjo, had his father, Crown Prince Sado, executed by locking him in a rice chest and starving him. His younger brother became the Grand Heir of Joseon in 1759 as he was intended to take over after their grandfather. He later became King of Joseon in 1776.

In 1870, duringKing Gojong of Joseon's 6th year of reign, his grave name wasUiryong Park (의령원;懿寧園).^[4] On June 7, 1949, his grave was moved to Wondang inGoyang.

• Father:King Jangjo of Joseon (조선 장조; 13 February 1735 – 12 July 1762)
  • Grandfather :King Yeongjo of Joseon (조선 영조; 31 October 1694 – 22 April 1776)
  • Grandmother :Royal Noble Consort Yeong of the Jeonui Lee clan (영빈 이씨; 15 August 1696 – 23 August 1764)
• Mother:Queen Heongyeong of the Pungsan Hong clan (헌경왕후 홍씨; 6 August 1735 – 13 January 1816)
  • Grandfather : Hong Bong-han (홍봉한; 1713–1778)
  • Grandmother : Lady Lee of the Hansan Lee clan (한산 이씨; 1713–1755)

1. Brother:King Jeongjo of Joseon (조선 정조; 28 October 1752 – 18 August 1800)
   1. Sister-in-law:Queen Hyoui of the Cheongpung Kim clan (효의왕후 김씨; 5 January 1754 – 10 April 1821)
2. Sister:Princess Cheongyeon (청연공주; 1754 – 9 June 1821)
   1. Brother-in-law: Kim Gi-seong (김기성; ?–1811)
3. Sister: Princess Cheongseon (청선공주; 1756 – 20 July 1802)
   1. Brother-in-law: Jeong Jae-hwa (정재화; 1754–1790)

• Crown Prince Sado
• Crown Prince Hyojang
• Jeongjo of Joseon
• Crown Prince Munhyo

• Korean crown princes who never acceded
• 18th-century Korean people
• 1750 births
• 1752 deaths
• House of Yi
• Korean royalty who died as children

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