Prince Jeongyang (; d. 23 March 1397), personal name Wang U () was the only full older brother of King Gongyang and nobleman in the early Joseon dynasty since his two daughters married both of King Taejo's son and grandson.
When King U and King Chang were deposed from the throne and their families were exiled, U led the army and stationed in Jangdan near Gaeseong to prepare for emergencies. Then, after his brother's ascension to the throne, he was promoted into Panmunhaseongsa (), Yeongsansasa () and Jongbusisa () and in 1391, he became Yeongmunhabusa ().
One year later, Yi Seong-gye established the new Joseon dynasty and King Gongyang's families were exiled, but since U's daughters married both of Yi's son and grandson, so he escaped from the riots while honoured as both of Prince Majeon () and Prince Gwi of Ui () at Angam Temple () in Majeon-gun, Gyeonggi Province (now Misan-myeon, Yeoncheon County, Gyeonggi Province) where the Goryeo royal ancestor rites were held by him and his descendants. Taejo was said to enjoyed Gyeokgu () with U and explained him why he given the Joseon royal title (it wasn't that Taejo forgive him because they were in-law, but Taejo said that it was like that honoured Mija from the Ju State to Song State ('주ëÂÂë¼ìÂÂì 미ìÂÂ를 ì¡ëÂÂë¼ì ë´Âàê²Âê³¼ ê°Âë¤'). Also, his sons were changed their clan into maternal one (No clan).
In 1394, U became a target for the treason case of the Wang clan which several officials insisted that he and his two sons got exiled or killed. However, King Taejo pardoned them every time on the grounds that they had to hold the Goryeo ancestral rite. After U's death in 1397 amid continued impeachment, the King personally sent a tribute and gave him a posthumous name.
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