When the lengthening vernal sun of 1253 had melted the northern snows this prophetic word was verified. The renegade Koryŭ general, Hong Pok-wŭn, told the emperor that the king had triple-walled the island of Kang-wha and would not move therefrom. War, ever welcome to these first Mongol emperors, was now afoot. The first detachment of 10,000 troops was led by the Emperor’s brother Song-ju. With many allies from the Yŭ-jin and other tribes he crossed the Yalu. Then the Mongol general, A Mo-gan, and the renegade Hong crossed and advanced as far as the Ta-dong River. Following these came Gen. Ya Gol-dă with sixteen chieftains in his train and with a formidable array of troops.
The envoy Sun who, we will remember, had married a Mongol princess, now wrote an urgent letter to the king saying “The emperor is angry because you persist in disobeying him and he is sending seventeen kings against you. But he says that if you will leave the island and follow out his commands he will even now recall the army. You have now an opportunity of giving your country a lasting peace. If you leave the island, send your son to the emperor and receive the Mongol envoy well, it will be a blessing to the kingdom of Koryŭ. If you will not do this, I beg of you to put all my family to death.”
Beneath this last appeal lay a terrible threat and the king realized it. A great council was convened and the universal voice was in favor of compliance; but a single voice was raised in opposition. It said “How much treasure have we squandered on this insatiable barbarian, and how many good men have gone as envoys and never returned. Let the king go out now from this place of safety and when we behold him a corpse our condition will be enviable indeed!” This word startles the assembly. Cowards that they are, they rise to their feet and with one voice applaud the stirring words and charge the king to stay in his island fortress and still defy the savage of the north.
Gen. Ya Gol-dă now sent a messenger to the King purporting to be from the Emperor saying “I have begun from the rising sun and I will conquer to its going down. All people rejoice but you, who do not listen. I now send Gen. Ya Gol-dă. If you receive him well, I will leave you in peace; if not, I will never forgive the offense.” Immediately putting his troops in motion the redoubtable general approached the strongest fortress in Whang-ha Province. It was surrounded by almost perpendicular precipices. The commandant laughed at the Mongols and defied them, and feasted in their sight. But the Mongols, directing all their energy at a single point, soon battered down a portion of the wall, set fire to the buildings with fire arrows, and with scaling ladders effected an entrance. The commandant hanged himself, and 4,700 of the garrison were put to the sword. All children above ten years old were killed and all the women were ravished.