The aristocratic fat cats were about to pay a dire price for their disregard, and in many cases flat out disrespect, for the military officers of their day. Military commanders and civil officials had previously held a similar social standing, but the rise of the aristocratic order had placed the military officials in an inferior position to their aristocratic counterparts. Civil officials slowly began to fill military positions at the beginning of the twelfth century, but it wasn't until the reign of Uijong ( 의종 ), who ruled from 1146 until 1170, that the rage of the military finally reached its breaking point. There were two particularly insulting events which directly contributed to the military revolt. The first of these occurred at Uijong's royal banquet in 1167. At this event, Kim Donjung ( 김돈중 ), who was the son of the famous Kim Busik and an advisor to Uijong, set fire to the beard of an officer named Jeong Jungbu ( 정중부 ) and then proceeded to mock him and the entire military. The final straw however, took place in 1170 when General Yi Soeung, who at the time was around 50 years old, was defeated in a martial arts competition by a much younger soldier. Following the event, a civil official name Han Roe began to insult the general and even slapped him in the face. Although the result was not immediate, this was the last in a series of disrespectful events that caused Jeong Jungbu, Yi Uibang ( 이의방 ), Yi Go ( 이고 ) and other military officials to rise up against the government.
"Death to all who but wear the civil official headdress!"
This was the rallying cry that united the military in their opposition to the civil officials. It goes without saying that the unified military force was easily able to massacre the defenseless civil officials (Kim Donjung and Han Roe of course met their end). One of the remaining aristocrats attempted to restore Uijong to power (he had been sent into exile following the rebellion) in 1173, but this attempt failed and resulted in the death of Uijong and another purge of civil officials.
The three leaders of the military revolt placed Myeongjong ( 명종 ) on the throne following the rebellion, but he was merely a puppet and the real power was held by the military. Unfortunately, as is usually the case with military regimes, the only thing that mattered during this time period was military might. This resulted in a very tumultuous time period in which power constantly shifted amongst the most powerful military officials. The first of the leaders to go was Yi Go, who was killed by Yi Uibang in his attempt to garner power. However, Yi Uibang was later killed by supporters of Jeong Jungbu, who was then later killed by General Gyung Daeseung ( 귱대승 ) in 1179. Gyung Daesung became ill and died in 1183 and power then passed to a former slave named Yi Uimin ( 이의민 ). Yi Uimin proved to be a ruthless dictator and was finally killed in 1196. Yi Uimin's death, and the subsequent rise to power of Choe Chungheon ( 최충헌 ), finally brought an end to nearly three decades of political turmoil in Goryeo
Choe Chungheon may have brought some order and stability to Goryeo, but he by no means was a benevolent ruler. He disposed of all who disobeyed his orders and asserted his supremacy over the throne by placing four different kings upon it. It should be noted that he did not do away with the monarchy, but simply removed all of its power and took it for himself. Choe also focused his attention on two other power struggles at the time. He asserted his power over the Buddhist monks by forcing them out of the capitol and destroying any of those who opposed with his powerful military. He also subdued many peasant uprisings through the use of military force or in some instances political appeasement. Choe's power was later solidified by Choe Chungheon's son, Choe U ( 최우 ). Choe U succeeded in creating a personal military and elite patrols to safeguard Choe's hold on power. He also created political offices through which he could wield power over the throne.
One of the unintended consequences of the military revolt was the spread of insurgency throughout the peninsula. Social order had prevailed in Korea since time memoriam, but the rise of military officials to the highest government offices introduced doubts to this previously hierarchical society. If the military officials could ascend the social ladder, why not the peasants? Peasant uprisings began in 1172, but it wasn't until 1193 that the movement really caught fire. Rebel bands of peasants were a harsh reality for the new military regime during the end of the twelfth and the beginning of the thirteenth centuries. And while the Choe regime succeeded for the most part in subduing these rebellions (some of which numbered in the tens of thousands), it became evident during this time period that the previously rigid social structure in Korea had become an artifact of a bygone era.
Well this didn't last too long, but Goryeo and the Mongols actually joined forces for a short period of time in their mutual quest to destroy the Khitan. The Mongols succeeded in forcing the Khitan into Goryeo territory and it was at this point that Goryeo and the Mongols teamed up. The Khitan eventually fell to the Mongol-Goryeo alliance in 1219. This however would prove to be the first and last cooperative effort between these two nations.
The Mongols began to demand tribute from Goryeo after the defeat of the Khitan and the increasingly unstable relationship between the two countries finally came to a head when the Mongols launched their first invasion in 1231. The two countries came to an agreement and ended the first invasion, but the agreement stipulated that Mongol governors would be placed in the northwest portion of Goryeo. However, Choe U decided to resist the Mongols and moved the capitol to Ganghwa Island. The Mongols were not very happy about this move and subsequently launched five more invasions of Goryeo over the next thirty years.
The military was not the only body resisting the Mongol invasions. The peasants also rose up in rebellion against their invaders. And it was the peasants who bore the brunt of the Mongol's wrath. While Goryeo's leaders enjoyed lives of luxury and safety on Ganghwa Island, the peasants fought tooth and nail for their country and were slaughtered by the Mongols as a result.
End of Military Rule
The Choe military regime was completely satisfied resisting the Mongols from their stronghold on Ganghwa Island. In contrast, the civil officials advocated for capitulation. The last of the Choe dictators, Choe Ui ( 최의 ), was assassinated in 1258. Some advocates of resistance remained for the next twelve years, but the policy of resistance was for the most part abandoned and in 1270 Goryeo returned its capital to Gaeseong and completely succumbed to Mongol rule.
Yuan's (the Mongols named themselves the Yuan Dynasty) first order of business for its newly acquired vassal state was to utilize Goryeo's location and military strength as a springboard for an invasion of Japan. The Mongols launched campaigns into Japan in 1274 and 1281, but both ended in failure. Goryeo was allowed to maintain its sovereignty and continue the line of the royal house, but all of the monarchs during this period were ultimately controlled by Yuan. In addition to asserting its dominance over the royal house, Yuan also demanded a substantial amount of tribute from Goryeo. Yuan's demands obviously led to a rift between the two countries and Goryeo jumped at its first opportunity to rid itself of Mongol control.
The End is Near
Decline of Yuan
Goryeo's opportunity to expel Yuan's influence from the peninsula arose during the reign of King Gongmin ( 공민왕 ), who ruled from 1351 until 1374. The upstart Ming dynasty had succeeded in forcing the Mongols to retreat to the north and Gongmin used this opportunity to remove Yuan's influence on the peninsula, purge the government of any Yuan supporters, and regain the land lost during the Mongol invasions. These changes opened the door for a large scale shift in Goryeo's government. After all, the royal house had not held any actual authority for almost 200 years. Yi Seong-gye ( 이성계 ) appeared to be just the man for the job.
Yi Seong-gye began his political career as a strong military commander responsible for warding off the incessant attacks of Japanese marauders. His entrance into politics came about as a result of King U's ( 우왕 ) decision to invade the Ming dynasty. Yi Seong-gye opposed the decision, but was entrusted with control of the military campaign. However, instead of following orders, Yi Seong-gye decided to reverse course and instead attack the capital, overthrow the king, and seize power for himself. Although it would be another three years until the official establishment of the Joseon Dynasty, for all practical purposes this event brought an end to the Goryeo Dynasty.
Emergence of the Literati
A new class named the literati (similar to the term "scholar"), which would eventually become the dominant social class in Korea, emerged during this time period. The literati was composed of educated men who supported an examination system as opposed to the traditional system of advancement based upon lineage. Many of these men also came from outside the capitol and owned small portions of land.
Neo-Confucianism and the Decline of Buddhism
Confucianism and Buddhism had previously succeeded in coexisting on the Korean peninsula for hundreds of years, but the advent of Neo-Confucianism during the fourteenth century put an end to the previously peaceful relationship between the two modes of thought. Neo-Confucianism attempted to explain the origins of man and of the universe, which was an area of thought previously reserved for Buddhism. Similar to the modern conflict between science and religion, this discrepancy between Neo-Confucianism and Buddhism eventually led to a decline in Buddhism on the peninsula.
Kim Busik's compilation of Korean history, which was known as the Samguk sagi and released in 1145, ignited a fascination with Korean history. As a result, many history books were written during this period. The most notable of these is the Samguk yusa, which like the Samguk sagi focuses on the Three Kingdoms Period, but rather than focusing on "facts", it instead investigates myths and beliefs during the time period.
The most notable artistic achievements from this time period are the wooden structures. Not because they were particularly exquisite, but because they are the oldest extant examples of wooden architecture in Korea. The oldest of these can be found in modern-day Andong. Wood has proven itself to be a very ineffective medium in Korea due to numerous invasions, which are the main reason that wooden buildings from previous time periods no longer exist.
Movable metal type was invented in Goryeo, which obviously paved the way for the widespread publication of books. The other major advance in technology was the introduction of gunpowder, which was passed to Goryeo by way of the Chinese.