Pyega ipjin

Pyega ipjin (廢假立眞) was an incident in 1389 in which Goryeo's Chief Royal Counselor and regent, Yi Seong-gye, drove King Chang from the throne and installed King Gongyang as ruler.

Background

In November 1389, late in the Goryeo period, Chief Royal Counselor Yi Seong-gye expelled King U's son, King Chang, from the throne and banished him. He then enthroned the royal clan member Wang Yo (King Gongyang), declaring him the true Wang and a king. One month after Gongyang's accession, on December 31, 1389, the two deposed rulers, Kings U and Chang, were both declared to be descendants of Shin Don and false Wang monarchs, and they were ultimately executed.

However, the so-called "non-royal theory" in this incident, that Kings U and Chang were the sons and grandson of Shin Don, is generally regarded as a fabricated slander, most likely created by Yi Seong-gye's faction to rationalize their political justification.