politics. Through his career Yi Ja-gyeom cultivated muban military officials, that after 960 had a lower status and enjoyed less perquisites than their civilian munban counterparts. Two of his most important allies were Choe Hong-jae, a high civilian official of a military background, and a military commander Cheok Chun-gyeong. With this power base Yi Ja-gyeom emerged as the most influential figure in the Goryeo politics. He became the Chief-Minister-Extraordinary in charge of all three chancelleries (samseong), while keeping the position of the head (superintendent, pansa) of the Ministry of Personnel (Yi-bu). He was also created a Duke (kong). Nevertheless, his authority never became absolute: he had to take heed of other factions both in execution of policies he favored and in rooting out the opposition. In foreign relations he was aligned with the Kyeongju Kim faction led by Kim Bu-sik and his brothers, advocating a submission to the newly established Jin. In 1123 the renewed Song offer of formal investiture was rejected. Jin stepped up the pressure on Goryeo by occupying Uiju (Poju) area along the Yalu river; from their point of view it was a repair of the frontier defenses. After a suppression of unrest in Balhae a secure North-Eastern frontier allowed Jin to focus on the Song. 1124–1126 In early 1124 Choe Hong-jae and military officers associated with him plotted to overthrow Yi Ja-gyeom, but were unsuccessful. Choe and the associates were purged from their positions and exiled. Following the purge Yi married one of his daughters to Injong, and increasingly filled the mid- and high-ranking government positions with his loyalists, including his five sons. He and his faction profited from seized property of the purged officials. The idea that Goryeo has to submit to Jin was still encountering resistance. The embassy dispatched in 1125 to Emperor Taizong of Jin was rejected by his officials because the correspondence it carried addressed the emperor improperly and did not use the term ‘servant' when referring to Goryeo. The question whether to accept that the mandate of the northern dynasty passed to Jin was debated through 1126. Eventually Kim and Yi convinced Injong and the reluctant officials to submit to Jin. By that time the Song were collapsing under Jin attack, Emperor Huizong abdicated, while a Goryeo embassy (that included Kim Bu-sik ) had to return without being able to reach Kaifeng. The embassy to Jin sent in 1126 presented the