Yi Ui-min was born of slave status, and his father Yi Seon was a salt trader and his mother a temple servant. According to the History of Goryeo, he was as tall as 1m 90 cm and possessed remarkable physical strength.
Military
Yi entered the capital defense command, where his outstanding Subak technique was noticed by the King Uijong and he was promoted to the byeoljang. In 1170, he got a position of the jungrangjang by the reward of joining the Goryeo warrior rebellion. In 1173, Kim Bo-dang had attempted to reinstate Uijong who had been dethroned against the grasping political power of Jeong Jung-bu. As a result, Yi had been ordered to return Uijong from his place of exile, Geoje, by rebel forces, only to kill him on his way back in Kyungju. Yi killed Uijong by snapping off his spine with his bare hands. He was said to have burst into a big laughter upon hearing the sound of Uijong's spine breaking. He then rolled up the dead body of Uijong in a blanket and dumped it in a lake. Afterwards, Yi Ui-min was promoted to general in recognition for killing Uijong. He then made it to the top post, chief captain, for the credit of putting down the Revolt of Jo Wi-chong, Governor of Pyongyang in 1174. At 1179, when Gyeong Dae-seung, who had an opposite political position against Jeong Jung-bu took the government and pushed away Jeong's people, Yi's power in the government significantly decreased, and his past murder of Uijong became the pretext that Gyeong would use to eliminate him. Yi had been in fear of an assassination attempt by Gyeong, thus he had placed guards everywhere in around his house. One day, he heard a pleasing rumor that Gyeong was killed. This rumor proved to be wrong though as in fact it had been Heo Seung, a close friend of Gyeong, who had died, not Gyeong himself. As a result of aware of it, Gyeong gave warning of Yi still more, Yi who was seized with fear, run away to Gyeongju on the pretext of illness.
Dictator
When Gyeong died by disease in 1183, King Myeongjong called Yi in to the Gaegyeong. Not believing the death of Gyeong, Yi refused the king's request several times, but finally came to the Gaegyeong after realizing Gyeong's death. Yi who was commissioned as a susagongjwabokya by Myeongjong had gotten a position of a dongjungseomunhapyeongjangsa panbyeongbusa in 1190 additionally. Yi who seized the political power, not only took bribes but also extorted private houses and lands. His family also committed many evil deeds. Especially his two sons, Yi Ji-young and Yi Ji-gwang who were called as "ssangdoja" by repute. Yi Jiyoung committed all sorts of brutality, killing whomever displaying contumacy to his authority and raping the pretty women, regardless of their marital statues. He even kidnapped and raped a royal concubine. Similarly, Mrs. Choe, Yi's wife, also had a tremendous sexual appetite, which eventually led to her demise after getting kicked out by Yi who had caught her red handed carrying on an adultery with one of their house servants. Yi's daughter was equally as infamously arrogant and lecherous as to disregard her husband, take up a separate residency and fool around with countless men.
Death and family's downfall
In 1196, having his pigeon snatched away by Ji-young, Yi's son, Choe Chung-soo went to his brother Choe Chung-heon to seek help. The Choe Chung-soo persuaded the Choe Chung-heon to carry out a plot to kill Yi together, to which he agreed after a momentary hesitation. Yi turns down King Myeongjong's request to accompany him to a Bojesa temple by making an excuse about his ill physical condition and sneaks out to a Mita Mountain cottage. Hearing it, the Choe brothers make their way to the cottage and stakes out the place. They eventually kill Yi, ambushing him when he comes out of the cottage and is about to climb on a horse. Having successfully carried out the assassination, the Choe brothers immediately head to the Gaegyeong, where they decapitated and exposed head of Yi on the street and call up troops with help from general Baek Jon-yoo. Hearing the news, the Myeongjong at the Bojesa temple hurries his way back to the Gaegyeong. Yi's sons Ji-sun and Ji-gwang battle against the Choe brothers only to run away in the end after having struggled on the defensive. As they flee, the Choe brothers lead their troops to the palace to ask the Myeongjong to allow them to put down the remaining insurgents loyal to Yi. With their authority granted by the Myeongjong, the choe brothers close up the castle gates to deter fleeing and went on to detain Yi's followers one by one. Meanwhile, they have general Han Hu capture and kill Yi Ji-young amid his frolick with Kisaengs. Hearing the news that Yi Ji-yeong had died, many people were said to be comforted and cheered. After then, Choe Chungheon killed all families and relatives of Yi Ui-min, and even sent people to every regions of the nation, wiping out all followers and slaves of Yi's. The survived two sons of Yi Ui-min, Yi Ji-sun and Yi Ji-Gwang, returned to Choe Chung-heon to beg for mercy and their pardon, but Choe heedlessly killed both of them, eradicating the last of Yi's clan.
