Mongol invasions of Korea

The Mongol invasions of Korea (1231 - 1270) consisted of a series of campaigns by the Mongol Empire against Korea, then known as Goryeo, from 1231 to 1270. There were six major campaigns at tremendous cost to civilian lives throughout the Korean peninsula, ultimately resulting in Korea becoming a vassal of the Mongol Yuan Dynasty for approximately 80 years.

The initial campaigns

Gojong of Goryeo (reigned 1213-1259) was the twenty-third king of the Goryeo dynasty. In 1225, the Mongol Empire demanded tribute from Goryeo and the Mongol envoy Chu-ku-yu was killed. His death was used by the Mongols as an excuse to invade Goryeo.

In 1231, Ögedei Khan ordered the invasion of Korea. The experienced Mongol army was placed under the command of General Sartai. The Mongol army crossed the Yalu river and quickly secured the surrender of the border town of Uiju. Choe U mobilized as many soldiers as possible into an army comprised largely of infantry, where it fought the Mongols at both Anju and Kusong. The Mongols took Anju; however, they were forced to retreat after the Siege of Kusong. Frustrated by siege warfare, Sartai instead used his armies' superior mobility to bypass the Goryeo army and succeeded in taking the capital at Gaesong. Elements of the Mongol army reached as far as Chungju in central Korean peninsula; however, their advance was halted by a slave army led by Ji Gwang-su where his army fought to the death. Realizing that with the fall of the capital Goryeo was unable to resist the Mongol invaders, Goryeo sued for peace. The cost of tribute was immense, if not absurd. The Mongols demanded 10,000 otter skins, 20,000 horses, 10,000 bolts of silk and clothing for 1,000,000 soldiers and a large number of children and craftsmen who would become slaves and servants of the Mongol empire. General Sartai began withdrawing his main force to the north in the spring of 1232, leaving seventy-two Mongol administrative officials stationed in various cities in northwestern Koryo to ensure that Koryo kept his peace terms. But Ch'oe U resolved not to accept the Mongol occupation without resistance.

In 1232, Choe U, against the pleas of both King Kojong and many of his senior civil officials ordered the Imperial Court and most of Gaesong's population to be moved from Songdo to Ganghwa Island in the Bay of Gyeonggi, and started the construction of significant defenses to prepare for the Mongol threat. Choe U exploited the Mongols' primary weakness, fear of the sea. The government commandeered every available ship and barge to transport supplies and soldiers to Ganghwa Island. The evacuation was so sudden that King Kojong himself had to sleep in a local inn on the island. The government further ordered the common people to flee the countryside and take shelter in major cities and mountain citadels or to nearby offshore islands. Kanghwa Island itself was a might defensive fortress. Smaller fortresses were built on the mainland side of the island and a double wall was also built across the ridges of Mt. Munsusan.

The Mongols protested the move, and immediately launched a second attack. The Mongol army was led by a traitor from Pyongyang called Hong Pog-won and the Mongols occupied much of northern Korea. Although they reached parts of the southern peninsula as well, the Mongols failed to capture Ganghwa Island, which was in reality only a few miles from shore, and were repelled in Gwangju. The Mongol leader Sartai (撒禮塔) was killed by a monk Kim Yun-hu (김윤후) in strong civilian resistance at the Battle of Cheoinseong near Yongin, forcing the Mongols to withdraw again.

Third campaign and treaty

In 1235, the Mongols began a campaign that ravaged parts of Gyeongsang and Jeolla Provinces. Civilian resistance was strong, and the Imperial Court at Ganghwa attempted to strengthen its fortress. Goryeo won several victories but the Goryeo military and Righteous armies could not withstand the waves of invasions. In 1236, Gojong ordered the re-creation of the Tripitaka Koreana, destroyed during the 1232 invasion. This collection of Buddhist scriptures took 15 years to carve on some 81,000 wooden blocks, and is preserved to this day. After the Mongols were unable to take either Ganghwa Island or Goryeo's mainland mountain castles, the Mongols began to burn Goryeo farmland in an attempt to starve the populace. When some fortresses finally surrendered, the Mongols executed everyone who resisted them.

In 1238, Goryeo relented, and sued for peace. The Mongols withdrew, in exchange for Goryeo's agreement to send the Imperial Family as hostages. However, Goryeo sent an unrelated member of the imperial line. Incensed, the Mongols demanded clearing the seas of Korean ships, relocation of the court to the mainland, the hand-over of anti-Mongol bureaucrats, and, again, the Imperial family as hostages. In response, Korea sent a distant princess and ten children of nobles, rejecting the other demands.

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