The plan of campaign of the Mongol ruler was as simple as it was bold. From his camp at Karakoram, on the Kerulon, he marched in a straight line through Kuku Khoten and the Ongut country to Taitong, securing an unopposed passage through the Great Wall by the defection of the Ongut tribe. The Kins were unprepared for this sudden and vigorous assault directed on their weakest spot, and successfully executed before their army could reach the scene. During the two years that the forces of Genghis kept the field on this occasion, they devastated the greater portion of the three northern provinces of Shensi, Shansi, and Pechihli. But the border fortress of Taitong and the Kin capital, Tungking, successfully resisted all the assaults of the Mongols, and when Genghis received a serious wound at the former place, he reluctantly ordered the retreat of his army, laden with an immense quantity of spoil, but still little advanced in its main task of conquering China. The success of the Khitan Yeliu Liuko had not been less considerable, and he was proclaimed King of Leaou as a vassal of the Mongols. The planting of this ally on the very threshold of Chinese power facilitated the subsequent enterprises of the Mongols against the Kins, and represented the most important result of this war. In 1213 Genghis again invaded the Kin dominions, but his success was not very striking, and in several engagements of no very great importance the Kin arms met with some success. The most important events of the year were, however, the deposition and murder of Chonghei, the murder of a Kin general, Hushahu, who had won a battle against the Mongols, and the proclamation of Utubu as emperor. The change of sovereign brought no change of fortune to the unlucky Kins. Utubu was only able to find safety behind the walls of his capital, and he was delighted when Genghis wrote him the following letter: "Seeing your wretched condition and my exalted fortune, what may your opinion be now of the will of heaven with regard to myself? At this moment I am desirous to return to Tartary, but could you allow my soldiers to take their departure without appeasing their anger with presents?" In reply Utubu sent Genghis a princess of his family as a wife, and also "five hundred youths, the same number of girls, three thousand horses, and a vast quantity of precious articles." Then Genghis retired once more to Karakoram, but on his march he stained his reputation by massacring all his prisoners--the first gross act of inhumanity he committed during his Chinese wars.