Ch 5 - Koryo and the Mongols
The Northern Frontier
Political turmoil in Kaesong surrounding the assassination of King Mokchong gave Liao Emperor Sheng Tsung an opportune pretext to invade Koryo. After years of fighting along the northern frontier, Koryo launched a massive attack that all but annihilated the Khitan army. The rising power of the Jurchen nomads in northeast Korea led to a rebuilding of Koryo's military forces and the loss of the northeast to Jurchen control.
King Songjong's sixteen year reign brought a number of lasting changes and reforms to Koryo, including the institution of the civil service examination system and efforts to bring the aristocracy into the central government. Songjong could not do enough however, to mollify the ever-scheming members of the aristocracy who harbored a burning desire for power. Following his death in 997, various ruling factions openly battled for control of the throne and contentious aristocratic clans became deeply embroiled in internal intrigues and disputes. The tumultuous transition of power that brought seventeen-year-old Mokchong to the Koryo throne masked the true state of affairs in the royal court. Behind the scenes, de facto control of the government rested in the tight grip of the dowager queen, a powerful woman from the Kim Ch'i-yang clan.
In 1009, one of the dowager queen's sons maneuvered to force King Mokchong to abdicate in favor of the queen's grandson. The young king responded to this serious challenge to his own succession by appointing a close relative, the son of former King Kyongjong, as the Crown Prince. To secure his personal safety, Mokchong turned for help to one of his most powerful military commanders, General Kang Cho, the military administrator for the northwest district. He ordered General Kang to Kaesong from the Pyongyang Garrison and charged him with the protection of the crown. General Kang dutifully brought his troops into the capital and, in a brief period of terror at the royal palace, viciously eliminated the dowager queen and members of the Kim Ch'i-yang faction responsible for the attempted coup.
Like Wiman of Old Choson, Kang Cho had far stronger ambitions than Mokchong ever imagined. General Kang quickly turned against the young king, assassinated him, and appointed himself supreme military commander of the Koryo army. The young Crown Prince, with the approval of the powerful Kim Un-bu clan of Ansan, assumed the throne as King Hyonjong, only to discover he reigned over a government now under the control of General Kang Cho.
North of the Yalu River, Liao Emperor Shengzong closely monitored the political turmoil in Kaesong ( - Koryo and the Khitan). Five years after his victory over the Song Chinese, the Liao emperor remained incensed over Koryo's trade monopoly with Song China and King Songjong's efforts to subjugate the Jurchen tribes in the northeast. Shengzong took particular offense at the brutal massacre of some ninety-five members of a Jurchen embassy whom he considered to be Liao subjects.
Kang Cho's bloody coup in Kaesong provided the Liao emperor an opportune pretext to invade Koryo under the guise of avenging King Mokchong's murder. In the winter of 1010, an army of 400,000 Khitan troops left the Naewon-song Fortress under the personal command of Emperor Shengzong and marched across the frozen Yalu River into the Koryo frontier. General Kang successfully fought off the first Khitan assault from defensive positions around the Sonch'on Garrison. Undaunted, the Khitan warriors regrouped and launched a second attack. This time they overran the garrison and captured General Kang. Despite repeated demands from the Khitan emperor that Kang Cho vow allegiance to him, the heroic Koryo general steadfastly refused to bow in submission. Emperor Shengzong executed him on the spot.
Emperor Shengzong's army defeated the Sonch'on Garrison and easily pierced Koryo's defenses, bypassing the coastal garrison at Kwaksan and pushing south to lay siege to the city of Pyongyang. Only a staunch defense by Koryo defenders prevented the fall of the city. When news of Kang Cho's death reached the royal court at Kaesong, the government nearly panicked. The king's ministers clamored for an immediate and unconditional surrender. King Hyongjong rejected the plea of his ministers and instead took the advice of one of his generals. Hoping to buy time for the remaining Koryo forces to reorganize and counterattack when the Khitan thrust lost its momentum, Hyongjong directed the court to move far south to the port city of Naju.
Emperor Shengzong continued his drive south. Khitan troops eventually reached the capital at Kaesong and took the city. The Khitan army savagely raped and pillaged its way through Kaesong, destroying a large number of precious monuments and documents. Hoping to end the hostilities, King Hyongjong attempted to sue for peace. The Koryo court quickly rounded up those officials responsible for the earlier massacre of the Jurchen envoys and handed them over to the Emperor Shengzong. The Khitan emperor haughtily ordered Koryo to cede the strategic border region then under the control of the Six Garrisons. He also demanded that if King Hyongjong wanted the Khitan to withdraw from Koryo, he should come to the capital at Liaoyang and show his obeisance to the Liao Dynasty. Hyongjong knew full well that such an act would amount to acknowledgement of Koryo's vassal status to the Liao emperor. The young king stubbornly refused such an absurd request and never took the royal journey north.
In the middle of critical negotiations with the Liao state in 1014, the military rebelled and led a coup d'état against the civil government. Two of the government's leading civil officials were beheaded. Ultimately however, the coup solved nothing. The underlying conditions that triggered the military revolt neither disappeared nor abated for over a century. Military officers still suffered the arrogant domination of a civilian government which continued to put civil bureaucrats in positions to which military men, in principle at least, should have been appointed.
Despite their success on the battlefield, the Liao invasion brought the Khitan no particular advantage. After driving deep into the heart of Koryo, Emperor Shengzong and his troops found themselves ever more dependent on thinly stretched supply lines that ran between the Naewon-song Fortress and Kaesong. Fearing he might be cut off and isolated deep within Koryo, Shengzong decided to withdraw his army. Koryo's warriors counterattacked the Khitan mercilessly during its northward retreat and inflicted horrendous casualties. Between twenty and thirty thousand Khitan soldiers reportedly died in their frantic attempt to recross the Yalu River into Liao.
Emperor Shengzong was hardly finished dealing with Koryo. Once the Khitan army shook off its disastrous defeat, it continued to launch numerous small-scale attacks in Koryo's northwest frontier, while the emperor continued to pressure King Hyongjong to accept his demands. The royal court in Kaesong continued steadfastly to refuse the Khitan emperor. Simultaneous with negotiations to settle disputes with Kaesong, Emperor Shengzong readied his forces for yet another major offensive, the final bloodbath in the long cycle of Khitan invasions.
Khitan combat troops under the command of General Xiao Baiya held two cities on the Koryo side of the Yalu River in anticipation of taking the region of the Six Garrison Settlements by force. Construction workers labored throughout the summer and autumn of 1018 to build a large, well-fortified bridge across the Yalu, completing the project in the dead of winter. General Xiao led a force of 100,000 men across the completed bridge onto Koryo's frozen countryside Koryo in December of that year. Columns of Koryo troops ambushed the Khitan from the moment they set foot on Koryo territory. After breaking out of the ambush, the Khitan army drove southward, only to meet even stiffer resistance in the region around the capital of Kaesong.
The Khitan were beset by continuous harassing attacks, forcing General Xiao to abandon all thoughts of conquest. His attention soon focused on the grave problem of trying to extricate himself from the hellish winter of northwest Korea. In their rush north toward the Yalu River, the Khitan army retreated headlong into the well defended Kusong Garrison near the northwestern town of Kuju. Koryo's General Kang Kam-ch'an led a massive attack that all but annihilated the Khitan army. Barely a few thousand of the Liao troops survived the bitter defeat at Kusong. Four years later, Koryo and the Liao dynasty reached a negotiated peace agreement and established normal relations. The Khitan never again invaded Koryo.
Koryo's defenses had weakened dramatically in the generation following General Kang Cho's death. Immediately following Koryo's peace agreement with the Liao dynasty, the royal court mobilized a labor force said to number upwards of 304,000 men to begin rebuilding the capital at Kaesong. In 1033, Koryo undertook a massive construction program to build a great defensive wall across its northern frontier to block not only the Khitan, but the Jurchen of eastern Manchuria as well. After eleven years of intensive labor, the massive rampart, modeled after China's northern defense line, linked fourteen walled towns in a line that stretched northward from the mouth of the Yalu River, through the mountains near the headwaters of the Chongchon and Taedong Rivers, to the east coast near Toryonp'o, the modern port of Yonp'o.
The Jurchen nomads, formerly subjects of the once vibrant kingdom of Parhae, viewed Koryo and the Liao dynasty as suzerain powers. They saw in Koryo the same things Koryo saw in China; a "parent country," the source of cultural and economic wealth. The Jurchen developed a strong desire to acquire the trappings of civilization that Koryo could provide; grain, fine textiles, hand-crafted goods, agricultural tools, and military weapons. Their Korean neighbors taught them to farm and Chinese prisoners taught them to work iron. In exchange, the Jurchen supplied Koryo with furs and horses. This mutually beneficial economic and cultural exchange fueled rapid social development among the Jurchen tribes. Not long after Koryo reached a peaceful settlement with the state of Liao, the relationship came to an abrupt end.
The trouble began when Ukkonae, chieftain of the powerful Wan-yen tribe in northern Manchuria, succeeded in unifying all the nomadic Jurchen tribes under his leadership. Pushing south, he extended his control over the Jurchen living in northeast Korea. Ukkonae's highly skilled Jurchen horsemen moved across the rugged Kaema Plateau and easily rode through and defeated Koryo infantry units whenever they encountered them. The rapid Jurchen success brought their own internal conflict between unification and continued subservience to Koryo ever closer to the surface.
King Sukchong's court viewed the growing Jurchen threat as a serious matter and moved to increase the size of Koryo's regular army. Sukchong instituted what amounted to a kind of mass conscription to raise and organize 170,000 men into the new Extraordinary Military Corps. The government drafted civil and military petty officials, merchants, members of aristocratic families, freeborn peasant farmers, even Buddhist monks and organized them into special cavalry and infantry units to augment the regular army's Six Garrison Divisions. Sukchong's new army under year-round training in preparation for a massive assault against the Jurchen.
In 1107, Koryo's Extraordinary Military Corps under the command of General Yun Kwan swept out of the mountain pass near modern Chongp'yong and routed Jurchen tribes living on the plains below. They hotly pursued fleeing Jurchen up the Hamhung Plain along the east coast as far north as Hongwon. During the campaign, General Yun's troops killed 9,000 Jurchen, took 5,000 prisoners, and destroyed some 130 villages.
To secure his military success in the northeast, General Yun Kwan ordered nine fortresses built at strategic locations throughout the area. The royal court tried to ensure future control of the territory by starting a campaign to encourage people from the south to move and settle in the region around the Hamhung Plain. Despite good intentions however, the campaign was doomed to failure almost from the start. The remote and rugged landscape of the northeast coast made the territory difficult to hold and defend. Furthermore, long communication lines made it virtually impossible for the court at Kaesong to react fast enough to repel the Jurchen who repeatedly mounted retaliatory attacks in the area. The occupation plan eventually failed. Alternating between diplomatic appeals and the nearly unending attacks, the chronic and indecisive warfare between Koryo and the Jurchen soon exhausted both sides. Ultimately, Koryo returned control of the northeast region to the Jurchen.
The internal divisions and tribal unrest among the Jurchen nomads precipitated soon led to the formation of a new regional power in northern Manchuria. A-ku-ta, Ukkonae's younger brother, united fractious Jurchen tribes under the banner of the powerful Wan-yen tribe and proclaimed the formation of the Jin dynasty in 1115. Almost immediately, the newly found power of the Jurchen turned against the Khitan monarchy in Liao. Before attempting a major invasion of Liao however, Jin moved to secure its southern flank by making a remarkable diplomatic overture to the Koryo court. The Jin leadership, confident of its strength, demanded that King Yejong conclude an alliance of peace and declare himself to be the Jin Emperor's "younger brother." Suspicious of Jin intentions, King Yejong's court could not and did not submit to such an insolent demand. Koryo responded by severing all relations with the Jin and intensified the buildup of its northern defenses. Meanwhile, across the Yellow Sea, Song China watched developments with an eye toward eliminating its old enemy; the people of "the Great Liao Country."