In 1211, the Khitan prince Yelü Liuge who had been serving the Jin as a military commander rebelled and seized a portion of Liaodong.

Based in Dongjing ("Eastern Capital"), Puxian Wannu declared the state of Dazhen ("Great Jurchen").

In the spring of 1216, Khitans fleeing from the Jin overran Puxian Wannu's territory and held the area from Dengzhou to Poju (Uiju).

[5] In 1216, the Mongols accompanied by Yelü Liuge chased the Khitan rebels to the Goryeo borders and launched an attack on Dafuying, located on an island in the lower course of the Yalu River.

Hazhen sent a letter carried by the translator Zhao Zhongxiang to Cho Ch'ung, the Goryeo commander in charge of the northwest, requesting provisions and demanding the two nations enter an Elder-Younger Brother relationship after the subjugation of the Khitans.

[9] Cho Ch'ung and Kim Ch'wiryŏ were in favor of meeting the Mongol demands but the Goryeo court was more apprehensive.

In the autumn of 1219, military commanders Han Sun and Ta Chi rebelled in Poju and defected to Puxian Wannu, who augmented their forces with 10,000 Eastern Jurchens.

Defense General Cho Sukch'ang and Deputy Commissioner Chŏn Kan surrendered Hamsin-chin to the Mongols.

When the second group heading south reached Chongju, Kim Kyŏngson at first tried to fight the Mongols but the entire city had already fled, so he retreated to Kuju Castle.

At Ch'ŏlchu (in Hamgyong Province), the men slit their throats and burned the granary and all the women and children rather than submit to the Mongols.Yongju, Sonju, and Kwakchu fell in October.

The Three Armies under the leadership of Yi Chasŏng departed Kaesong in early October and fended off a surprise attack by 8,000 Mongol soldiers.

They used carts of grass and wood as well as towers to try to scale the walls but the defenders countered with molten iron, setting fire to the siege machines.

They set up 30 catapults and breached the city wall in 50 places but they were repaired while Pak Sŏ made a successful sortie and drove off the attackers.

Pak Sŏ and Ch'oe Ch'unmyŏmg, defender of Chaju, were almost executed but the Mongols spared them owing to their courage, which they admired.

The royal family relocated to Ganghwa and commissioners were sent out to the provinces to instruct the people to take refuge in mountain citadels or coastal islands.

Hong escaped with his family to Mongol territory in Liaoyang and Shenyang while the Western Capital's people were resettled in island locations.

In the kurultai of 1235, Ögedei Khan gave orders to attack Goryeo, Southern Song, the people west of the Volga, and to push to the edge of Kashmir.

By late 1235, Mongol and Eastern Jurchen troops under the command of Tanqut-Batur had taken Yonggang, Hamjong, Samdŭng, and Haep'yong (modern Sangju).

[34] Goryeo did not attempt to field an army against the Mongols and offensive actions were limited to raids against small patrols.

During the invasion, King Gojong ordered a set of printing blocks for the Buddhist canon to be created and work began in 1237.

A royal relative, Wang Sun, the Duke of Yŏngnyŏng, was also sent as a hostage to the Mongol court while pretending to be the crown prince.

The arrival of the 17-year old pretend prince at the Mongol court in 1241 and the resumption of tribute missions secured a moment of respite for Goryeo until 1247.

Gojong did meet Mongol envoys on the mainland a few years later, but Ch'oe U and his successors, the ones responsible for defending Goryeo, remained on the island for the rest of their lives.

[41] In early 1253, 300 Eastern Jurchen cavalry surrounded Tŭngju in the northwest and a small raiding party was reported in the summer.

Some inhabitants of Wonju who had been taken captive by the Mongols returned to Goryeo to inform the authorities that Möngke had ordered an invasion led by the prince Yekü, Sung-chu, Amukan, and Hong Pok-wŏn.

[42] In the winter of 1253, Yekü fell ill at Chungju and returned north to recover, leaving Amukan and Hong Pok-wŏn in command of field operations.

So Möngke blamed the Goryeo court for deceiving him and killing the family of Lee Hyeong, who was a pro-Mongol Korean general.

Mongke Khan once again sent a large army along with Prince Yeongnyeong and Hong Pok-wŏn, who had been taken hostage by Jalaltai as the captain, and gathered at Gapgot Daedan (甲串岸) and showed momentum to attack Ganghwa Island.

However, Kim Sugang (金守剛), who had just gone to Mongolia, succeeded in persuading Mongke Khan, and the Mongols withdrew from Goryeo.

Beginning with Wonjong, for approximately 80 years, Goryeo was a vassal state and compulsory ally of the Yuan dynasty.