As a result of the King's refusal to recognize the child, intense debate and speculation surrounding the lineage of the boy ensued and Monino was not permitted to enter or live inside the palace.
Gongmin officially pronounced Monino to the Royal Court as Crown Prince and renamed him "U", recording his mother to be a deceased palace maid of the Han clan.
[3] Tensions over this crucial foreign policy protocol had not been resolved when the Ming Dynasty proclaimed its intention to establish a command post headquartered in the Ch'ollyŏng pass at the southern end of the Hamgyŏng Plain in 1388.
There was a growing feeling in Kaesŏng that Goryeo needed to take some kind of preemptive action against China, and advisors to King U eventually goaded him into attacking the powerful Ming armies.
[5] Returning to Kaesŏng and, after overpowering the royal court's defenders and removing (then killing) General Ch'oe Yŏng, Yi Seong-gye usurped the throne from Goryeo's Dynasty and took control of the government.