Yeon Gaesomun (? - 666), was a Goguryeo general of noble birth. He killed King Yeongnyu in 642 and seized supreme power. He installed King Bojang as a puppet ruler. As military dictator, he led the country's defense against the initial attack of Silla and Tang.

Yeon launched his coup d'etat at the end of a lengthy power struggle within the Goguryeo aristocracy. Charged with the defense of the country's borders, he had grown impatient with the country's policy of appeasement towards Tang. Taking matters into his own hands, he rounded up about a hundred members of the opposing faction and had them killed together with King Yeongnyu. Thereafter he looked after the country's foreign and domestic policies himself.

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. However, these good relations with Tang did not last long, as Tang grew angry with Goguryeo interference in their diplomatic contacts with Silla. This led to a massive punitive expedition in the winter of 645, in which only the steadfast resistance of Yang Man-chun at a border fortress saved the rest of Goguryeo from serious danger.

The strict nature of Yeon's military rule can probably be credited with the kingdom's ability to resist the Silla-Tang invasion of 661, despite a lengthy siege of the Goguryeo catpial at Pyongyang. After his death, the country was weakened by a succession struggle between his sons, and fell easily to the Silla-Tang army in 668.

Yeon was also called Cheon Gaesomun (천개소문/泉蓋蘇文) in Chinese texts, to avoid the conflict of the character used in their Emperor's name that time. (See naming taboo ). He is also sometimes referred to as Gaegeum (개금/蓋金).

Much of what we know about Yeon Gaesomun comes from the Samguk Sagi's accounts of Kings Yeongnyu and Bojang (Goguryeo vols. 8-10).

See also

• History of Korea
• List of Korea-related topics
• Three Kingdoms of Korea