The Mongol invasions of Korea

By Bloodswan

Korea and Chinese history were always closely linked and the invasion of the Mongols was not an exception.

The first military contacts between the Mongols and Korea came as a result of the Mongol’s defeat of the Khitan. These people were of the same ethnic stock as the Kara-Khitai who Genghis Khan had already defeated and whose Liao dynasty had already fallen to the Jin. In 1216 the Mongols drove the Khitan to the Yalu river which was on the border of Korean Koryeo rule.

The campaign against the Khitan

After the Mongol attacks on the Khitan, the Khitan were forced across the Yalu river. When the Koreans refused them supplies, the Khitan began looting and pillaging nearby towns and the Koreans were forced to fight back against them.

During the winter of 1216 the Mongols crossed the Yalu river in pursuit of the Khitan. Their first real resistance was met at walled city of Kangdong. Heavy snow had made the roads impassable and the Khitan presumed they were safe. Kangdong was also well supplied and a good place to settle down for the winter

The Mongols asked the help of the Koryeo government to aid them on the grounds that they had come to liberate the Koryeo from the Khitans. The rulers were hesitant to co-operate with what they perceived to be the “most inhuman of Northern barbarians”. When an agreement had been reached, the Korean commander Cho jung sent his general Kim Ing-yong to the Mongols with some supplies. Kim was ordered to observe closely and at Taech’on, Kim allowed his Hwarang (archers) to assist the Mongols in their attack of the Khitan defences.

In 1219 a large Korean army joined the Mongols and assaulting Kangdong. After some Khitan gave themselves up, their leader hung himself and the Khitan in Korea were no more.

With their immediate objective complete and after demanding an enormous tribute, the Mongols left Korea. The Mongols had not completely gone and at the small border town of Uiji, a small Mongol force remained with instructions to “practise the language of Koryeo and wait for our return”.

The Mongols return

An uneasy peace lasted until 1225 when a Mongol envoy came to collect a tribute. He was supposedly killed by bandits but the Mongols suspected the Koreans and had it not been for a strain of Mongol military resources elsewhere, invasion would have occurred then and there.

It was not until 1231 that Khan Ogedai ordered the invasion of the Koryeo as part of a campaign against China. The Koreans having refused to help the Mongols in a campaign against the Jin. In August a large Mongol force under the general Sartaq (also called Sartai or Sartak) laid siege to Uiju. Uiju surrendered not long after the initial assault. From here the Mongols headed south to besiege Kuju. Kuju was to become famous in the annals of siege warfare as it experienced one of the longest and best recorded sieges of all Mongol conquests.

General Kim Ch’ungon defended the eastern and western walls, while Kim Kyongson held the southern part. Overall command was held by the heroic Pak So. Based on an account from Pak-So, when the Mongol vanguard arrived at the southern gate, Kyongson leading twelve soldiers and the city patrol ordered them to ride out and face the Mongols. The patrol threw themselves to the ground and refused. Kyongson, with only twelve soldiers rode out to battle. Kyongson shot an arrow and knocked a Mongol flagbearer from his mount. The twelve soldiers fought bravely and Kyongson was hit by an arrow. The Mongol vanguard was temporarily halted.

The siege continued with furious Mongol attacks against Kuju’s walls. They loaded carts with wood and grass hoping for fires to sweep through the city. Meanwhile they built siege towers, rams and even began mining underneath the walls. In response the Koreans bombarded the Mongols with molten iron projectiles flung from traction trebuchets, threw burning straw at the siege towers and countermined the Mongol miners.

Sartaq sent an interpreter to instruct them to submit. Pak-So refused to surrender. The Mongols then began scaling the walls with ladders but Pak-So met them and fought them off with slashing implements. All the ladders that were made were smashed and the walls could not be approached. The siege continued. During the siege a senior Mongol officer remarked “I have followed the army since my hair was in plaits as a youth and so I am accustomed to seeing the cities of the Earth attacked and fought over. Still, I have never seen a city undergo an attack such as this that did not submit in the end”.

While Kuju was holding out, three Korean armies left Kaesong to come to Kuju’s relief but the vanguard under Yi Chasong was attacked whilst resting by a Mongol force of 8,000. An arrow hit Yi and a spear killed his companion. The relief army went into disarray. The Mongols then doubled their efforts against Kuju but still it held out. To this the Mongols sent raiding parties south to ravage the lands. Mongol forces bypassed most pockets of resistance and soon captured the capital at Kaesong. Some of Sartaq’s horsemen reached as far south as Ch’ungju, where a slave army led by Chi Kwang-su halted their advance in a heroic battle fought to the last man. The armies that ravaged the lands terrified the Koryeo government, who opened up negotiations.

Unfortunately for the brave defenders of Kuju, their own government had ordered the surrender of the city. Pak-So was so astonished he refused and was given a sentence of execution from the King, Gojong. He was saved execution from his admiring Mongol enemies. A new tribute which included gold, silver, pearls, silk, 20,000 otter skins and 10,000 horses was demanded. In addition thousands of hostages were released and Mongol officers and garrisons were to be stationed in all major cities.

Korea seemed doomed but the stubborn resistance of Kuju had pointed out the difficulties posed by fortified cities to Mongol warfare. This of course was gradually overcome as later campaigns into Russia, China, the Middle East and Persia show but the Korean campaign would soon reveal a further weakness in Mongol warfare.

In 1232 the Koryeo government slipped away from Kaesong and took refuge on the fortified island of Kanghwa. For the first time in the Mongols were faced with a sea barrier. The watery gap was only a kilometre wide but in spite of several attempts to overcome Kanghwa, the Mongols could not capture it. Frustrated by this the Mongols began ravaging Korea once more. Koryeo’s peasants operating from mountain fortresses and refuges in Korea’s numerous small coastal islands, Koryeo’s peasants took up arms and stiffly resisted the Mongol occupation. In August Sartaq swept through the Han river valley and besiege a small mountain fortress called Ch’oin-song. It was defended by a warrior monk named Kim Yun-hu who succeeded in placing an arrow through Sartaq’s eye. This is the only known incident of the commander of a Mongol Army being killed in battle and it forced the Mongols to retreat.

Further Mongol campaigns

Korea was listed alongside Europe and Song China as the targets listed in the great Kuriltai held in 1235. In acknowledgement of the fierce resistance the Koreans had put up in the previous campaign the best Mongol troops were assigned to Korea. The only other place where elite troops were earmarked was for the Russian-European campaign.

During the early stage of the campaign a Koryeo official defected to the Mongols which allowed P’yongyang to be taken. With their rear safeguarded the Mongols ignored the Korean court at Kanghwa, the armies continued south as far as Kyongju. Before reaching Kyongju the mountain fortress at Ch’ungju was besieged.

Once again refusing to surrender, the Koreans led by Commander Song Munju responded to the Mongol opening with a barrage of missle fired from catapaults. The Mongols responded by firing flaming bales of straw soaked in human fat. General Song however withstood the assault and earned a reputation alongside the great Pak-So.

In 1247, the Mongols began the fourth campaign against Koreans, demanding the Koryeo royal family as hostages. With the death of Guyuk Khan in 1248, however, the Mongols withdrew again.

Upon the ascension of Mongke Khan in 1251, the Mongols again repeated their demands. When Koryeo refused, the Mongols began a large campaign in 1253.

The civilian resistance was strong and the Koreans won several victories but the Korean military could not withstand the waves of invasions. Another siege took place at Ch’ungju in 1253, where the Korean commander was the same Kim Yun-hu of Ch’oin fame. Once again Yun-hu refused to surrender. The Mongols turned their attention to a nearby town. The Mongols created a blockade outside of the town and the people were forced to drink the blood of their livestock. When the town finally fell all of its’ inhabitants were slaughtered.

Way back in 1236, King Gojong had ordered the restoration of the Tripitaka Koreana, destroyed during the 1232 invasion. This collection of Buddhist scriptures which took 15 years to carve on some 81,340 wooden blocks was first carved in 1011 whilst repeling the Khitans. It was restored in the hope that the Mongols could be expelled through religious activity. The new carvings were begun in 1237 at the Chondungsa temple on Kanghwa island and wasn’t completed until 1251. The carvings can be seen today at the Haiensa temple. The carving appeared to have worked when in 1254 the Mongols withdrew their armies after another attempt to take Kanghwa ended in disaster.

The Final campaigns

Only a few months passed before the Mongols invaded Korea in 1254. Korean resistance was immediate and as determined as ever. Ch’ungju was attacked again but its defenders were aided by a storm which forced the Mongols to withdraw. The Mongols still could not attack Kanghwa but they tightened their grip on the rest of Korea by constructing their own fortifications. This enabled them to launch widespread raids with greater security. It proved to be a decisive shift in the fortunes of war for the Mongols. Mongols under Jalairtai launched four devastating invasions in the final successful campaign against Korea between 1253 – 1258.

Throughout all of the previous raids the Koryeo resistance from Kanghwa had been led not by the king but by the hard-line anti-Mongol Choe family who had slowly turned their leadership into a dictatorship. Since Choe Chung-heon, Koryeo had been under this military dictatorship, actually ruled by the private army of the powerful Choe family. When their leader Choe Ui was assassinated in 1258, King Gosong assumed control of the government again and indicated his intention to negotiate a peace. Koreans sent hostages into the Mongol camp as a proof of his good will.

A group of hard-line Korean rebels deposed the new Koryeo king Wongjong, determined to keep on fighting. Mongol troops were invited in by the Korean royal family to help crush the rebellion and by 1270 the last of the remaining rebels fled to Jeju island.

In 1273 the Korean crown prince was married to one of Khubilai Khan’s daughters in a final diplomatic settlement. Half of Jeju island was given over to the Mongols to graze their horses and Korea became a tributary ally to the Mongol Yuan dynasty. All seemed well until in 1274 Khubilai humiliated the Korean king by commandeering his country’s military and naval resources for the Mongol invasion of Japan.

The Koryeo dynasty survived under Mongolian influence until King Gongmin began to push Mongolian forces back around 1350.


Siege weapons of the Far East (1) by Stephen Turnbull
Genghis Khan and the Mongol invasions by Stephen Turnbull
Genghis Khan – Life, death and resurrection by John Man
Various internet sources