Yeon Gaesomun

From New World Encyclopedia
Yeon Gaesomun
Hangul 연개소문
Hanja 淵蓋蘇文
Revised Romanization Yeon Gaesomun
McCune-Reischauer Yŏn Kaesomun

Yeon Gaesomun (연개소문; 淵蓋蘇文) (603 - 665) was a powerful and controversial general and military dictator in the waning days of Goguryeo, one of the Three Kingdoms of ancient Korea. In 642, Yeon discovered that King Yeongnyu and some of his official were plotting to kill some of the more powerful military officers, including himself, because they were seen as a threat to the throne. He immediately went to Pyongyang, where his forces killed the king and one hundred government ministers. He placed the king's nephew, Bojang (r. 642-668), on the throne and had himself appointed to the post of Dae Mangniji (대막리지; 大莫離支), the highest possible rank of Goguryeo, assuming control over Goguryeo military and political affairs. He successfully repelled invasions of the Tang dynasty in 645, and of a Tang-Silla alliance in 681.

After his death in 666, a power struggle broke out among his three sons. The eldest, Yeon Namsaeng, defected to Tang and then led the Tang invasion which ultimately ended Goguryeo in 668. Yeon Gaesomun has long been a focus of historical controversy. Many historians hold him responsible for the fall of Goguryeo to the Tang. He has become a hero of modern Korean nationalists, for whom he is a symbol of the time when, at the height of their power, the Koreans unambiguously triumphed over the Chinese.



Goguryeo was the largest of the three kingdoms into which ancient Korea was divided until 668. According to tradition, it was founded in 37 B.C.E., in the Tongge River basin of northern Korea by Chu-mong, leader of one of the Puyo tribes native to the area. Modern historians have dated its origins to the second century B.C.E. A royal hereditary system had been established by the reign of King T'aejo (53–146 C.E.). King Sosurim (reigned 371–384) centralized the authority of the throne and made Goguryeo into a strong political state. Goguryeo expanded its territory during the reigns of King Kwanggaet'o (391–412) and King Changsu (reigned 413–491), and at the height of its influence, the entire northern half of the Korean peninsula, the Liaotung Peninsula, and a considerable portion of Manchuria (Northeast Provinces) were under Goguryeo (Koguryo) rule. During the Sui (581–618) and T'ang (618–907) dynasties in China, Goguryeo (Koguryo) began to suffer encroachment from China. In 668, allied forces of the southern Korean kingdom of Silla and the T'ang dynasty conquered Goguryeo, and the entire peninsula came under the Unified Silla dynasty (668–935).

King Yeongnyu of Goguryeo

King Yeongnyu (영류왕; 榮留王; r. 618-642) was the 27th king of Goguryeo, younger half-brother of the 26th king, Yeong-yang (영양왕; 嬰陽王), and son of the 25th king, Pyeongwon (평원왕; 平原王). He assumed the throne when Yeong-yang died in 618. That same year, the Tang Dynasty replaced the Sui Dynasty in China. Since Goguryeo was recovering from the Goguryeo-Sui War, and the new Tang emperor was still completing the unification of China, and neither country was in a position to initiate new hostilities, Goguryeo and Tang exchanged emissaries. At the request of Tang, a prisoner exchange was carried out in 622, and in 624, Tang officially presented Taoism to the Goguryeo court, which sent scholars to China the following year to study Taoism and Buddhism.

Early life

Yeon Gaesomun was born to an illustrious family who had traditionally been influential in national defense and political affairs. According to one legend, the progenitor of Yeon Gaesomun was a spirit of the lake. From early childhood, Yeon was aggressive, showing no willingness to compromise, and had an overweening pride. According to tradition, at the age of nine years he already carried five swords, and would have men prostrate themselves so that he might use their backs to mount or dismount his horse.

Yeon was born at Goguryeo mountain, which had five beautiful springs of running water, where Yeon practiced martial arts every day. Later, Mongol invaders completely blocked its flow. At fifteen, Yeon tried to inherit his father’s political position of “Mangniji.” The aristocracy objected, saying that Yeon was cruel and oppressive, upon which Yeon apologized with tears for his defects. The noblemen were touched by Yeon’s apology and agreed to appoint Yeon, “Mangniji'.”

Rise to power

Very little is known of Yeon's early days, until he became the Governor of the Western province (西部). In 629, Silla's Kim Yu-sin took Goguryeo's Nangbi-seong.

In 631, as Tang gained strength under Li Shimin (Tang Taizong), it sent a small force to destroy a monument commemorating Goguryeo's victory over their predecessors, the Sui. The campaign was unsuccessful for the Chinese, who failed to capture strategic points in numerous attacks. In response, Goguryeo built the Cheolli Jangseong ( 천리장성; 千里長城) a network of military garrisons to defend the western border of the Liaodong area from Tang invaders. The project began in 631, under the supervision of Yeon Gaesomun, and the preparation and coordination was completed sixteen years later in 647. During this time, Goguryeo continued its battles to recover its lost territory from the southern Korean Silla kingdom.

There had been a long-standing power struggle between the military generals and the officials of the Goguryeo court. King Yeongnyu and some of the government officials felt that the army was becoming a serious threat, and plotted to kill some of the more powerful military officers, intending to kill Yeon Gaesomun, whose power and influence were rapidly overtaking the throne's, first. In 642, Yeon discovered the plot, and immediately went to Pyongyang, where he invited one hundred government ministers to a lavish banquet to celebrate his rise to the position of Eastern Governor. Yeon's soldiers ambushed and killed all the ministers present at the banquet. Yeon then proceeded to the palace and murdered the king. According to traditional Chinese and Korean sources, Yeon's men dismembered the dead king's corpse and discarded the pieces.

Yeon Gaesomun took control of the court and placed the king's nephew, Bojang (r. 642-668), on the throne. Yeon then had himself appointed to the post of Dae Mangniji (대막리지; 大莫離支), the highest possible rank of Goguryeo, making him responsible for Goguryeo military and political affairs. Yeon assumed de facto control over Goguryeo affairs of state until his death around 666.

Goguryeo-Tang War and Tang-Silla alliance

After defeating Goguryeo's western ally, the Göktürks, the Tang forged an alliance with Goguryeo's rival, Silla. This increased tensions between Tang and Goguryeo.

In the beginning of Bojang’s rule, Yeon was briefly conciliatory toward Tang China. He supported Taoism at the expense of Buddhism, and in 643, sent emissaries to the Tang court to request Taoist sages, eight of whom were brought to Goguryeo. Some historians believe this request was simply a tactic to pacify the Tang and allow Goguryeo time to prepare for a Tang invasion, which would inevitably occur if Yeon acted on out his ambitions to annex Silla.

Relations with Tang deteriorated, when Goguryeo launched new invasions of Silla. In 645, Taizong of Tang launched an invasion of Goguryeo, and was successful in conquering a number of major border city fortresses. However, Taizong's main army was held back for several months at Ansi Fortress by the dogged resistance of the Goguryeo general, Yang Man-chun. Yeon Gaesomun defeated the elite marine force sent by Taizong to take Pyongyang, Goguryeo's capital, and, according to the Joseon Sanggosa, immediately marched his legions to relieve Yang's Goguryeo forces at Ansi Fortress. Taizong’s forces, caught between Yang's army in the front and Yeon's counter-attack closing in behind them, and suffering from the harsh winter and dangerously low food supplies, were forced to retreat to China. During the retreat, a large number of Taizong's soldiers were slain by Yeon and his pursuing army, but Taizong and the bulk of the invading army escaped. Taizong inflicted heavy casualties to both soldiers and civilians on Goguryeo's side, and Goguryeo was never again able to launch attacks on China, as it once had during the height of its power.

Historians speculate that after Taizong's failure to conquer Goguryeo, Taizong and his son, Gaozong, became involved in a personal rivalry with Yeon. After Emperor Taizong's death in 649, Gaozong launched two more unsuccessful invasions of Goguryeo in 661 and 667. Yeon's legendary defeat of the Tang forces in 662, at the Sasu River (蛇水, probably present-day Botong river), during which the invading general and all thirteen of his sons were killed in battle, is considered by many Koreans to be one of the three greatest military victories in Korean history.

Eventually, faced with increasing domestic problems in China, Tang was forced to retreat. However, the three invasions inflicted sever damage on its economy and the population, and Goguryeo never recovered. Both Silla and Tang continued their invasions for over eight years, ultimately leading to the demise of Goguryeo. As long as Yeon Gaesomun was alive, though, Tang and Silla were not able to conquer Goguryeo.


The most likely date of Yeon's death is that recorded on the tomb stele of Namsaeng, Yeon Gaesomun's eldest son: The twenty-fourth year of the reign of Bojang (665). However, the Samguk Sagi records the year as 666, and the Japanese history Nihonshoki gives the year as the twenty-third year of the reign of King Bojang (664). He apparently died of natural causes.

Fall of Goguryeo

Yeon Gaesomun had at least three sons, (eldest to youngest) Yeon Namsaeng, Yeon Namgeon, and Yeon Namsan. After his death, the country was weakened by a succession struggle between his brother and his three sons and fell relatively swiftly to the Silla-Tang armies.

Yeon Namsaeng (淵男生 연남생 634-679), the eldest son, succeeded his father as the second Dae Mangniji (대막리지, 大莫離支) of Goguryeo. When he was nine years old, his father had begun giving him to official titles, first seonin 先人, and subsequently jungli sohyeong 中裏小兄, jungli daehyeong 中裏大兄, and jungli uidu daehyeong 中裏位頭大兄 (obscure Goguryeo titles whose exact nature is unknown). Yeon Namsaeng, was said to have become Dae Magniji sometime before the death of Yeon Gaesomun, who apparently stepped down from the position and took the honorary position of Tae Dae Magniji.

After the death of his father, Yeon Namsaeng prepared for war with the Tang, and set out on an inspection of the border fortresses in Liaodong, and other fortresses throughout the kingdom. Before his departure, he put his brothers, Yeon Namgeon and Yeon Namsan, in charge of Pyeongyang. Namgeon and Namsan took advantage of their brother's absence to take control of Pyeongyang and the Royal Courts. They falsely accused Namsaeng of being a traitor, and forced the Emperor to order Namsaeng's arrest. At the urging of his son, who had escaped death at the hands of his uncles, Namsaeng fled to Tang China, where he was given a high position in the Tang military. From there, he led a Tang-sponsored military campaign against Goguryeo with the hope of regaining power.

Namsaeng led the Tang army to victory in 668, and ultimately destroyed Goguryeo. Following the surrender of numerous cities in northern Goguryeo, the Tang army bypassed the Liaodong region and captured Pyongyang, the capital of Goguryeo. Yeon Jeongto, the younger brother of Yeon Gaesomun, surrendered his forces to the Silla general Kim Yushin, who was advancing from the south. In November, 668, Bojang, the last king of Goguryeo, surrendered to Tang Gaozhong. Namsaeng died in the domains of the Tang-established Protectorate General to Pacify the East, or Andong Duhufu (安東都護府), the Chinese administration established in Pyeongyang following the fall of Goguryeo in 668, to administer the former Goguryeo domains. He was buried on Mt. Mang (邙山) in Luoyang 洛陽, Tang’s eastern capital.

Namsaeng's tomb stele, along with that of his brother Namgeon, has been discovered. Namsaeng's biography (Quan Nan Sheng 泉男生傳) appears in the Xin Tangshu (New History of Tang), book 110. The Chinese rendering of Namsaeng’s family name is Cheon 泉 (Chinese Quan) rather than Yeon 淵, most likely because Yeon (Chinese, Yuan) was the given name of Tang Gaozu 高祖 (Li Yuan 李淵), founder and first emperor of Tang, and by Chinese tradition could not be applied to another.


The series of wars between Goguryeo and the Tang is one of the most important conflicts in the history of Northeastern Asia. The wars are generally regarded as the main reason for the demise of the once-powerful Goguryeo kingdom, which for several centuries provided a cultural and political counterbalance to China. The suppression of the Goryeo kingdom made China the dominant civilization.

Yeon Gaesomun is viewed by many historians as the chief cause of, as well as a central protagonist in, this important series of wars. It is speculated that his assassination of King Yeongnyu may have been one of the reasons why Tang launched the first failed invasion of Goguryeo in 645. His ambitions to annex Silla were certainly a provocation. Yeon was an able general and succeeded in repelling the Tang invasions in 645 and 662. However, his style of rule as a military dictator caused instability and undermined the traditional system of recruiting officials and administrators from a broad political base, rendering the state less capable of comprehending and responding to new political developments in Tang and Silla. The power struggle which broke out among his three sons after Yeon’s death was the final blow; when the eldest son Yeon Namsaeng defected to Tang, he was able to organize the final invasion which crushed Goguryeo.

The repeated wars against Tang were costly, decimating the rural population in the northern regions and weakening Goguryeo's production base.

After the fall of Goguryeo, several attempts were made to re-establish it. In 698, Balhae(Pohai) was founded by Daejoyoung, a descendant of Koguryo. In official documents sent abroad by the king, Balhae (698-926) boasted of itself as the successor of “Goryeo” (Koguryo). The kingdom of Koryo (918-1392), which succeeded Balhae, resurrected the name of "Koryo," which was the state title of Goguryeo.[1]

Historical controversy

Yeon Gaesomun has long been at the center of several historical controversies.

One concerns his personal character and motivation. Later Confucian scholars criticized Yeon for the coup and the regicide that brought him to power, portraying him as a disloyal subject who sought personal power above all else. In particular, extant Tang and Silla sources have consistently portrayed Yeon as a brutal and arrogant dictator. These sources include the story that Yeon carried five swords at a time, and would have men prostrate themselves so that he might use their backs to mount or dismount his horse. Modern nationalist historians dismiss these Tang and Silla sources as biased calumnies, and argue that Yeon's single-mindedness and success in defending Goguryeo testify to his patriotism.

Yeon's detractors blame him for needlessly provoking the Tang to attack Goguryeo and thereby ensuring its downfall. They point out that, while Goguryeo remained a formidable regional power before Yeon assumed power, it was completely destroyed by Silla and Tang within a short time soon after his death. Yeon's defenders claim that the Tang invasion of Goguryeo was inevitable, and that King Yeongnyu’s appeasement of Tang bought only a temporary delay.

For many modern Korean nationalists, Yeon is a hero and a symbol of the time when, at the height of their power, the Koreans unambiguously triumphed over the Chinese. During the renascent conflict between South Korea and China over the historical ownership of part of Manchuria, Yeon has undergone a dramatic rehabilitation, and is now admired by many South Koreans, most of whom are descendants of the people of Silla.

Another controversy exists over the sources used to support the defeat of the Tang Dynasty by Goguryeo. Some sources, such as Sin's Joseon Sangosa, claim that Taizong was forced into the outskirts of Beijing, but Sin's account has been challenged on the basis that it lacked support in traditional Korean and Chinese sources. For example, he stated that 100,000-200,000 Tang soldiers died, but both the ancient Korean history Samguk Sagi[2] and ancient Chinese histories Book of Tang,[3] New Book of Tang,[4] and Zizhi Tongjian[5] put the figure at 20,000, stating that there were only 100,000 Tang soldiers in the entire invading army. The modern Chinese historian Bo Yang has speculated that the Yeon may have had the records altered so that he could claim credit for Yang Manchun's victory over Tang.[6]


  1. Korean Net, Downfall and Succession of Koguryo.
  2. Samguk Sagi, vol. 21三国志. Retrieved October 20, 2007.
  3. Book of Tang, vols. 3, 199舊唐書. Retrieved October 20, 2007.
  4. New Book of Tang, vols. 2, 220唐書. Retrieved October 20, 2007.
  5. Zizhi Tongjian, vols. 資治通鑑/卷197, 資治通鑑/卷198.
  6. Bo Yang Edition of the Zizhi Tongjian, vol. 47.

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Preceded by:
Yeon Taejo
Daedaero of the Eastern Province of Goguryeo
642 - 665
Succeeded by:
Yeon Namsaeng
Preceded by:
Eulji Mundeok
Magniji (Prime Minister) of Goguryeo
642 - ?
Succeeded by:
Yeon Namsaeng
Preceded by:
Dae Magniji (Grand Prime Minister) of Goguryeo
642 - 665
Succeeded by:
Yeon Namsaeng


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