Ko-gu-ryŭ soon heard the ominous news and she took it as a presage of evil for herself. She immediately[immediately] threw a powerful army across the Sil-la border and stormed the Ch’il-jung Fortress. The records naively remark that they filled the commander as full of arrows as a hedgehog is of quills.
Now that Păk-je had been overcome China took up with alacrity the plan of subduing Ko-gu-ryŭ. The great final struggle began, that was destined to close the career of the proudest, hardiest and bravest kingdom that the peninsula of Korea ever saw. The Păk-je king who had been carried to China died there in 661. In that same year Generals Kye-p’il, So Chŏng-bang and Ha Ryŭk, who had already received their orders to march on Ko-gu-ryŭ, rendezvoused with their forces at Ha-nam and the warriors of the Whe-bol together with many volunteers from other tribes joined the imperial standards. The plan was to proceed by land and sea. The Emperor desired to accompany the expedition, but the death of the empress made it impossible.
Meanwhile matters in Păk-je were becoming complicated again. A man named Pok Sin revolted against the government, proclaimed Pu-yŭ P‘ung, the son of a former king, monarch of the realm and planned a reëstablishment of the kingdom. This was pleasing to many of the people. So popular was the movement that the Emperor feared it would be successful. He therefore sent a summons to Sil-la to send troops and put it down. Operations began at once. Gen. Yu In-gwe besieged Ung-jin the stronghold of the pretender and chased him out, but a remnant of his forces intrenched[intrenched] themselves and made a good fight. They were however routed by the combined Sil-la and Chinese forces. But in spite of this defeat the cause was so popular that the country was honeycombed with bands of its sympathisers who gained many lesser victories over the government troops and their Sil-la allies. The Sil-la general, Kim Yu-sin, was very active, passing rapidly from one part of the country to another, now driving back to the mountains some band of Păk-je rebels and now holding in check some marauding band from Ko-gu-ryŭ. He was always found where he was most needed and was never at a loss for expedients. It is said that at this time rice was so plentiful in Sil-la that it took thirty bags of it to buy a single bolt of grass cloth.
That same autumn the Chinese engaged the Ko-gu-ryŭ forces at the Yalu River and gained a decided victory. Then the fortress at Ma-eup San fell into their hands. This cleared the road to P‘yŭng-yang, and the Chinese boldly advanced and laid siege to that ancient stronghold. At the same time the Emperor ordered Sil-la to send troops to coöperate with the imperial army. She obeyed, but with great trepidation, for the fame of Ko-gu-ryŭ’s arms made this seem a matter of life and death. She was obliged to comply, however, or lose all the vantage ground she had gained in the Emperor’s favor. There were still some Ko-gu-ryŭ forces in the north and they were attempting to check the advance of a large body of Chinese reinforcements. It was late in the autumn and the Yalu was frozen. Taking advantage of this the Chinese crossed in the night and falling suddenly upon the unsuspecting army of Ko-gu-ryŭ inflicted a crushing defeat. It is said that 30,000 Ko-gu-ryŭ soldiers were killed in this engagement. The speedy downfall of Ko-gu-ryŭ seemed now inevitable, but a sudden timidity seized the Emperor, who feared perhaps to let his army winter on Korean soil. So he sent orders for an immediate retreat back to Chinese territory. The generals before P‘yŭng-yang were deeply chagrined and indeed found it impossible on account of lack of provisions to obey the command at once. Soon the Sil-la army arrived before P‘yŭng-yang with full supply of provisions. These the Chinese took and the greater part of them reluctantly broke camp and marched back to China, leaving Sil-la in a frame of mind better imagined than described.
While Ko-gu-ryŭ was staggering under the terrible reverses inflicted by the Chinese, events of interest were taking place in the south. The kingdom of T‘am-na on the island of Quelpart had always been a dependency of Păk-je, but now found it necessary to transfer her allegiance to Sil-la. The king of T‘am-na at that time was To-dong Eum-yul.
The mischief-maker, Pok-sin, was again in the field. Now that he was relieved of pressure he came back to the charge and took Ung-jin from the Chinese. At the earnest request of the governor the Emperor sent Gen. Son In-sa with a small army to aid in putting down this dangerous malcontent. Pok-sin was obliged to retire to Chin-hyŭn where he fortified himself strongly. Success seems to have turned his head for he began to carry himself so proudly that his followers arose and put him to death and then sent a messenger to Ko-gu-ryŭ and to Japan asking aid against the Chinese. The latter responded by sending a considerable force to the shores of Păk-je to coöperate with this hardy band of men who were honestly fighting for the independence of their country.
In 663 the Emperor conferred upon the king of Sil-la the title of Tă-do-dok of Kye-rim.
It appears that when the Chinese retired from before P‘yŭng-yang and left the Sil-la forces in such a delicate position, some of the Chinese were allowed to remain there on the plea that if all were removed it would invite an outbreak of the Păk-je revolutionists. Now as the year 663 opened the Emperor reinforced them by a powerful army under Gen. Son In-sa. Sil-la also sent the flower of her army under command of twenty-eight generals to join the Chinese before P‘yŭng-yang. But the plan of operations was changed. It was decided to move southward and complete the subjugation of the troublesome Păk-je patriots and their Japanese allies. The combined Chinese and Sil-la armies marched toward Chu-ryu fortress where the revolutionists were supposed to be intrenched. On their way they met the Japanese disembarking, on the banks of the Pak River. They were put to flight and their boats were burned. The march was continued and the fortress was duly invested. It fell straightway and the pretender to the Sil-la throne was captured. This was followed by the surrender of all the revolutionists and their Japanese friends. The last fortress to fall was that of Im-jon, now Tă-heung, after a desperate struggle.
The war was now at an end. The dead were buried, a census was taken of the people in the Păk-je capital, aid was given to the poor, and the people were encouraged to return at their peaceful avocations. Expressions of satisfaction at what seemed to be the return of peace were heard on all sides.
Gen. Yu In-gwe, who had been left in charge of the[the] Chinese troops before P‘yŭng-yang when the Emperor ordered the retreat, now sent word to the Chinese capital that as his soldiers had been in the peninsula two years without seeing home he feared they might mutiny. He received orders to return to China with his men but he decided to wait till the grain that his men had sown should ripen. The Emperor then appointed Pu-yŭ Yung the brother of the last king of Păk-je to the position of governor of all the territory formerly embraced in Păk-je. He received the title of Tă-do-dok of Ung-jin, and was urged by the Emperor to govern well. This was in 664.