The military ruler, Kim Jun(金俊) established peace negotiations with Mongol in 1259, on condition of Taejachinjo(太子親朝). In the beginning of military rule, Kim Jun could not capture government power, completely. So, He aimed to prevent invasion of Mongol Army, implementing the majority of Mongol Six Duty(蒙古六事). Kim Jun’s political power fulfilled to Taejachinjo, payment of annually tribute(歲貢), installation of relay stations(驛站), and dispatch of Darugachi(達魯花赤) out of Mongol Six Duty. But Kim Jun put off Jogun(助軍) and census(籍民), fundamental duty of Mongol Six Duty. This attitude of Goryeo military ruler resulted from following reasons. First, Mongol Emperor, Kubirai(忽必烈) imposed Jogun and census to Goryeo dynasty for the purpose of preventing resistance against Mongol. Second, Kubirai intended to bring down Kim Jun’s political power through the pressure on perfect performance towards Mongol Six Duty. The latter half of Kim Jun’s political power, Mongol Empire forced strongly to fulfill Jogun and census to Kangdo Court(江都 朝廷). Military ruler, Kim Jun was up for transferring the capital to strategic island which was located on the southern part. But his plan failed eventually, because of refusal of the king Wonjong(元宗) and peace claimers within Kangdo Court. After this, Kim Jun’s secret plan was reported to Mongol Emperor by Goryeo envoy. In 1268, Mongol Empire dispatched a large scale of envoy group by way of excuse for expedition to Japan. Mongol envoy pressured Kim Jun’s political power mostly, claiming personnel mobilization, provisions procurement, and battleship production. At that time, Wonjong succeeded in assassinating Kim Jun and his brother Kim Seungjun(金承俊), mobilizing a lot of eunuchs in Kangdo palace. Also, Wonjong won success to eliminate Kim Jun’s family and his faction, instigating Im Yeon(林衍) who was a adopted son of Kim Jun. As the result, Kim Jun’s political power collapsed and the resistance of Goryeo military rule against Mongol was weakened.