By the reign of King Pyeongwon of Koguryo in the late 6th century, the pluralistic international order in East Asia that had been ongoing since the 4th century had changed rapidly. The Sui dynasty was founded and emerged as a superpower in East Asia after dominating the Göktürks in the north and unifying China in 589 CE. The Sui dynasty desired to establish unitary international order centered in its homeland. Thus, the Sui dynasty did not recognize the Koguryo's supremacy in Northeast Asia and marched toward the Liao River region in defiance. In response, some of the forces in Northeast Asia, including the Khitan and Mohe tribes, broke away from Koguryo and allied with the Sui.
During this time of change, King Yeongyang of Koguryo (reign: 590-618 attacked the western Liao River region of the Sui dynasty. Emperor Wen (reign: 581-604 of the Sui dynasty immediately went on the counterattack. An army and navy comprised of over 300,000 soldiers were mobilized to battle Koguryo. However, the Sui supply lines were severely disrupted due to a rainy season, and the navy was crippled by a typhoon. The Sui counterattack in 598 CE had failed before it even began.
The Sui attempted another attack on Koguryo in 612 CE. To attack Koguryo, Emperor Yang of Sui (reign: 604-618 mobilized over one million troops for his campaign. It was the single largest army ever mobilized in history. Nevertheless, Koguryo was able to thwart the Sui army. Koguryo's success was primarily due to the consolidated efforts of the major aristocracies including King Yeongyang and General Eulji Mundeok, and the nation's defenses were strong enough that no city in the Liaodong region fell to the Sui. The Battle of Salsu, led by General Eulji Mundeok, was one of the decisive battles of the war.
Additional campaigns were launched in 613 and 614 CE by the Sui dynasty. By this time, however, the people of Sui had already grown restless over the war against Koguryo. Peasant rebellions had sprung up throughout the country, and major aristocrats such as Yang Xuangan had revolted against the Sui. For these reasons, the attempted conquest of Koguryo could not continue. Caught in a vortex of rebellions, the Sui dynasty finally collapsed in 618 CE.
Following the Sui dynasty, the Tang dynasty secured the central regions of China. Initially, the Tang dynasty desired friendly relations with Koguryo. Koguryo had become significantly weakened in the war against the Sui dynasty. Thus, the two countries shared friendly relations for a short period. In the late 620s, however, the Tang dynasty resolved domestic and international turmoil to emerge as a leading powerhouse in East Asia. Soon after, the Tang dynasty exerted diplomatic pressure on Koguryo. Like the Sui, the Tang dynasty wanted to establish international order with its nation at the center. In response, Koguryo built the Cheolli Jangseong (literally "Thousand-Li Wall to defend against an attack by the Tang dynasty. At this time, however, the Koguryo aristocracy divided into two major parties, the hardliners and moderates.
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[There is] a man named Gaesomun, also known as Gaegeum. His surname is Cheon, and he bedazzled people by claiming he was born in water. He is cruel and violent in nature. His father was a Daedaero (Prime Minister). Upon his father's death, Gaesomun naturally sought to receive the position but was unable due to the disdain of the citizens. He bowed his head and apologized to the public and requested the official rank. He stated that if he is found unsuitable, he would bear no regrets when invalidated. He was eventually granted the position through the public's compassion. However, he was so cruel and violent that several officials consulted with Geonmu (King Yeongnyu of Koguryo) to have him killed. When Gaesomun discovered this plot, he gathered all the tribes' [militaries] and requested the presence of the ministers to a great feast. He had the guests murdered upon arrival, nearly one hundred people. He ran into the palace, murdered Geonmu, tore his body into pieces, and then threw them into a ditch. [Yeon] placed Bojang, the son of Geonmu's younger brother, on the throne and appointed himself as the Magniji to do with the government as he pleased. [Magniji] is an official position corresponding to the Minister of Military Affairs Secretary General of the Tang dynasty.
(New Book of Tang, Vol. 219, Dong Yi Series, Koguryo)
As indicated by the above excerpt from the "New Book of Tang," Yeon Gaesomun faced elimination from the many great ministers who opposed him. In 642 CE, Yeon Gaesomun instigated a coup d'état. Through this action, he eliminated the major aristocratic forces who opposed him as well as King Yeongnyu. Yeon Gaesomun subsequently placed Jang (King Bojang of Koguryo on the throne. Thus, Yeon Gaesomun, a hardliner, seized political control of Koguryo.
The aftermath of Yeon Gaesomun's coup reached far throughout Koguryo. It is said that Ansi Fortress was involved in armed conflict due to their opposition of Yeon Gaesomun. The signs of infighting had emerged. From the perspective of the Tang dynasty, Yeon Gaesomun's political upheaval was a great opportunity to attack Koguryo. On the surface, Yeon Gaesomun's successful assassination of the King was a justifiable cause for conquest. And so in 645 CE, Emperor Taizong of Tang (reign: 626-649 led an attack on Koguryo.
Unlike the war with Sui, however, several Koguryo cities in the Liaodong region fell to the Tang in 645 CE. The Tang forces broke through defenses in the Liaodong area and marched toward Pyongyang through Gungnae Fortress. In this critical situation, Ansi Fortress put forth a formidable resistance. For several months, Ansi Fortress repelled the 150,000-strong army led personally by Emperor Taizong of Tang. Emperor Taizong eventually withdrew. On several occasions, Emperor Taizong sent armies to attack Koguryo without much success.
While Koguryo was busy fighting wars against the Sui and Tang dynasties, Baekje and Silla stayed active. The two countries, through the Sui and Tang dynasties, attempted to contain Koguryo even while at constant war with each other. In the midst of such complex international relations between the Three Kingdoms, Silla was most disadvantaged. In 648 CE, Kim Chunchu of Silla (King Taejong Muyeol formed a military alliance with the Tang dynasty. The Silla-Tang alliance was formed. The Silla-Tang alliance first attacked and conquered Baekje in 660 CE. The alliance then continued their offensive to attack Koguryo.
Koguryo was initially successful in thwarting attacks by the Silla-Tang alliance. In addition, as the revival of Baekje was being actively developed, the Tang dynasty was hesitant to continue their efforts in attacking Koguryo. However, the situation changed rapidly after the death of Yeon Gaesomun in 665 CE. Yeon Gaesomun's first son Namsaeng, who had succeeded his father as ruler, was in conflict with his two younger brothers Namgeon and Namsan. Due to this fact, Koguryo was embroiled in infighting. After losing power to his two younger brothers, Namsaeng surrendered to the Tang dynasty and joined forces to attack Koguryo in an attempt to regain control.
As such, Koguryo was no longer able to counter the enemy's attacks due to the infighting. Eventually, the capital Pyongyang fell to the Silla-Tang alliance in 668 CE. King Bojang and the major aristocracies of Koguryo were taken prisoner and transported to the Tang capital Chang'an (modern-day Xi'an). Subsequently, the displaced people of Koguryo attempted to revive the state through the efforts of Geom Mojam, Anseung, and GoYeonmu among others but were ultimately unsuccessful in rebuilding the dynasty.
- [note 001]
- 「History of the Three Kingdoms」 Vol. 20, Koguryo Annals 8, King Yeongyang of Koguryo
「History of the Three Kingdoms」 Vol. 20, Koguryo Annals 8, King Yeongyang of Koguryo
Encyclopedia of Korean Culture, King Yeongyang of Koguryo
Encyclopedia of Korean Culture, King Yeongyang of Koguryo
- [note 002]
- Doopedia, Emperor Wen of Sui
Doopedia, Emperor Wen of Sui
- [note 003]
- Doopedia, Emperor Yang of Sui
Doopedia, Emperor Yang of Sui
- [note 004]
- 「History of the Three Kingdoms」 Vol. 44, Series 4, Eulji Mundeok
「History of the Three Kingdoms」 Vol. 44, Series 4, Eulji Mundeok
Encyclopedia of Korean Culture, Eulji Mundeok
Encyclopedia of Korean Culture, Eulji Mundeok
- [note 005]
- 「History of the Three Kingdoms」 Vol. 20, Koguryo Annals 8, King Yeongyang of Koguryo, 7th month of the 23rd year
「History of the Three Kingdoms」 Vol. 20, Koguryo Annals 8, King Yeongyang of Koguryo, 7th month of the 23rd year
Encyclopedia of Korean Culture, Battle of Salsu
Encyclopedia of Korean Culture, Battle of Salsu
- [note 006]
- Doopedia, Yang Xuangan
Doopedia, Yang Xuangan
- [note 007]
- Encyclopedia of Korean Culture, Cheolli Jangseong
Encyclopedia of Korean Culture, Cheolli Jangseong
- [note 008]
- 「History of the Three Kingdoms」 Vol. 49, Series 9, Yeon Gaesomun
「History of the Three Kingdoms」 Vol. 49, Series 9, Yeon Gaesomun
East Asian Historical Figures, Yeon Gaesomun
East Asian Historical Figures, Yeon Gaesomun
Encyclopedia of Korean Culture, Yeon Gaesomun
Encyclopedia of Korean Culture, Yeon Gaesomun
- [note 009]
- 「History of the Three Kingdoms」 Vol. 20, Koguryo Annals 8, King Yeongnyu of Koguryo
「History of the Three Kingdoms」 Vol. 20, Koguryo Annals 8, King Yeongnyu of Koguryo
Encyclopedia of Korean Culture, King Yeongnyu of Koguryo
Encyclopedia of Korean Culture, King Yeongnyu of Koguryo
- [note 010]
- 「History of the Three Kingdoms」 Vol. 21, Koguryo Annals 9, King Bojang of Koguryo
「History of the Three Kingdoms」 Vol. 21, Koguryo Annals 9, King Bojang of Koguryo
Encyclopedia of Korean Culture, King Bojang of Koguryo
Encyclopedia of Korean Culture, King Bojang of Koguryo
- [note 011]
- Doopedia, Emperor Taizong of Tang Dynasty
Doopedia, Emperor Taizong of Tang Dynasty
- [note 012]
- 「History of the Three Kingdoms」 Vol. 5, Silla Annals 5, King Taejong Muyeol of Silla
「History of the Three Kingdoms」 Vol. 5, Silla Annals 5, King Taejong Muyeol of Silla
Encyclopedia of Korean Culture, King Taejong Muyeol of Silla
Encyclopedia of Korean Culture, King Taejong Muyeol of Silla
- [note 013]
- 「History of the Three Kingdoms」 Vol. 49, Series 9, Namsaeng, Namgeon, Namsan
「History of the Three Kingdoms」 Vol. 49, Series 9, Namsaeng, Namgeon, Namsan
「New Book of Tang」 Vol. 110, Series 35, Zhuyi Cheon Namsaeng
「New Book of Tang」 Vol. 110, Series 35, Zhuyi Cheon Namsaeng
「Translated Ancient Korean Stone Monument Inscriptions」 Cheon Namsaeng Epitaph
「Translated Ancient Korean Stone Monument Inscriptions」 Cheon Namsaeng Epitaph
「Koguryo Stone Monument Inscriptions about China」 Cheon Namsaeng
「Koguryo Stone Monument Inscriptions about China」 Cheon Namsaeng
East Asian Historical Figures, Cheon Namsaeng
East Asian Historical Figures, Cheon Namsaeng
Encyclopedia of Korean Culture, Yeon Namsaeng
Encyclopedia of Korean Culture, Yeon Namsaeng
- [note 014]
- 「History of the Three Kingdoms」 Vol. 49, Series 9, Namsaeng, Namgeon, Namsan
「History of the Three Kingdoms」 Vol. 49, Series 9, Namsaeng, Namgeon, Namsan
Encyclopedia of Korean Culture, Yeon Namgeon
Encyclopedia of Korean Culture, Yeon Namgeon
- [note 015]
- 「History of the Three Kingdoms」 Vol. 49, Series 9, Namsaeng, Namgeon, Namsan
「History of the Three Kingdoms」 Vol. 49, Series 9, Namsaeng, Namgeon, Namsan
「Translated Ancient Korean Stone Monument Inscriptions」 Cheon Namsan Epitaph
「Translated Ancient Korean Stone Monument Inscriptions」 Cheon Namsan Epitaph
「Koguryo Stone Monument Inscriptions about China」 Cheon Namsan
「Koguryo Stone Monument Inscriptions about China」 Cheon Namsan
Encyclopedia of Korean Culture, Yeon Namsan
Encyclopedia of Korean Culture, Yeon Namsan
- [note 016]
- Doopedia, Geom Mojam
Doopedia, Geom Mojam
- [note 017]
- Doopedia, Go Anseung
Doopedia, Go Anseung
- [note 018]
- Doopedia, Go Yeonmu
Doopedia, Go Yeonmu