The “Red-Head Robbers” were led by Kwan Sŭn-sang and P‘a Tu-ban. They now took the city of Mukden and entering Liaotung, sent a letter to the king of Koryŭ saying “We have now consolidated our power and intend to set up the Sung dynasty again.” The Mongols were thus beset on both sides and were in desperate straits. Three thousand of the “Red-Heads” crossed the northern border and carried fire and sword into the frontier towns. A Mongol general, deserting the banners of his waning clan, took service with these people. His name was Mo Ko-gyŭng. He collected 40,000 men and crossed the Yalu. Eui-ju fell forthwith and the prefect and a thousand men perished. Chöng-ju soon fell and In-ju was invested, but a stubborn resistance was here encountered. The prefect, An U, was the only prefect in the north who was not afraid of the invaders. He made light of their power and by swift counter-marches and brilliant manoeuvers succeeded in making them fall back to Chöng-ju. In the mean time Gen. Yi An was sent north to P‘yŭng-yang to take charge of the army of defense. The tide of fortune had turned again and the invaders were in full march on P‘yŭng-yang. A council of war was held at which it appeared that all the generals were about equally frightened. With a powerful force in hand and an easily defended town to hold they still considered only how best to make a retreat. Some were for burning everything behind them and retiring to some point more easy of defense; but Gen. Yi An thought they had better leave a large store of provisions in the city, for the enemy would pause and feed there until everything was gone, and this would give the Koryŭ army time to gain needed reinforcements. This course would also appear so foolish to the enemy that few preparations would be made to meet the Koryŭ troops later. This plan was adopted and the army retired into Whang-hă Province and left the gates of P‘yŭng-yang open to the invaders. This caused the greatest consternation in the capital, and every citizen was under arms. The king immediately sent and deprived Gen. Yi An of the office which he had so grievously betrayed and put the command into the hands of Gen. Yi Seung-gyŭng. The invading host was now feasting in P‘yŭng-yang and the king and queen in Song-do were practicing horse-back riding with the expectation that they would be obliged to leave the capital. It was the beginning of winter and the cold was intense. The Koryŭ soldiers died by hundreds and the people were being wantonly killed by foraging parties of the “Red Heads.” The records say that they left “heaps upon heaps” of dead in their track.