It is said that in order to decide about the removal of the capital the king had recourse to that form of divination which consisted in making scrawls at random with a pen and then examining them to see what Chinese characters the marks most resembled. At first they did not favor a change, but after several trials the favorable response was obtained.
The year 1359 beheld a recurrence of the dreaded Japanese incursions. At this time the robbers burned 300 Koryŭ boats at Kak-san. An official, Yi Tal-jung, was sent to govern the great north-eastern section of the land. He was a friend of Yi Whan-jo, the prefect of Sang-sŭng. As he approached that place his friend Yi Whan-jo came out to meet him, accompanied by his son Yi Song-gye who was to become the founder of the present dynasty, and whom we shall designate by his posthumous title T‘ă-jo. When Yi Whan-jo handed his friend a cup of wine he drank it standing, but when Yi T‘ă-jo handed him one, so the story runs, he drank it on his knees. When the father demanded why this greater deference was shown his son the guest replied, “This boy is different from us,” and, turning to the young man, he continued. “When I have passed away you must always befriend my descendants.”
The Japanese raids had now reached such alarming proportions that an extra wall was built about Song-do and all the government granaries along the coast were moved far inland to be out of the reach of piratical parties, who would naturally hesitate to go far from their boats.
The breaking up of the Mongol power was foreshadowed by the act of a certain Mongol district Hă-yang which, with its garrison of 1,800 men, now came and enrolled itself under the banner of Koryŭ. How had the mighty fallen! Less than eighty years before the world had trembled beneath the hoof-beats of the “Golden Horde.” This was followed by the submission of a wild tribe in the north called Pang-guk-chin, and a Mongol rebel sent a messenger with gifts to the court of Koryŭ. Meanwhile the Japanese were ravaging the southern and western coasts without let or hindrance. It was a curious spectacle, a country eaten up by its own excesses receiving humble deputations from former masters and at the same time being ridden over rough-shod by gangs of half-naked savages from the outlying islands of Japan.
There was one tribe in the north however, called the Hong-du-jŭk or “Red-Head Robbers,” who threatened to invade the country, but forces were sent to guard against it. In the case of the Japanese marauders the difficulty was to know where they were going to strike next. There was military power enough left in Koryŭ had it been possible to so place the forces as to intercept or bring to action the robber gangs. The Japanese had really begun to threaten Song-do itself and the king wished to move the capital to Su-an in Whang-hă Province. He went so far as to send a commissioner to look over the site and report.
The king was not blessed with an heir, and in 1360 he took a second wife, which was the cause of constant quarrelling and bickering.
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.
As in duty bound the Koryŭ forces went north and engaged the invaders at P‘yŭng-yang. At first the latter were successful and a thousand Koryŭ troops were trampled under the hoofs of the enemy’s horses; but in the end the “Red Heads” were defeated and, retreating northwards, were hotly pursued as far as Ham-jŭng. There they were reinforced and attempted to make a new stand; but the Koryŭ troops, drunk with success, attacked them with such abandon that they were obliged to build a palisade within which they intrenched themselves. The Koryŭ generals surrounded this stockade and, by a simultaneous assault of horse and foot, broke through the barrier and put the occupants, numbering 20,000, to the sword. The leader, Whang Chi-sŭn was taken alive. A remnant fled to the Yŭn-ju River where the ice broke beneath them and 2,000 perished. The few survivors made a desperate[desperate] stand on a hill but were starved out and compelled to continue their flight, in which hundreds more were cut down along the road; and at last, out of 40,000 men who had come across the Yalu, just three hundred recrossed it and were safe.
Hardly had this happened when seventy boat-loads of these same “Red Heads” arrived at P‘yŭng-ju and soon after a hundred boat-loads more disembarked at An-ak and scoured the surrounding country. They were, however, soon put to flight by Gen. Yi Pang-sil whom the king rewarded richly for his services.