Yang Manchun is the name given to the Goguryeo commander of Ansi Fortress in the 640s. Ansi Fortress was located on the Goguryeo–Tang border, probably present-day Haicheng. Yang is sometimes credited with saving the kingdom by his successful defense against Tang Taizong.
Name
Whether "Yang Manchun" was his real name is unclear. Kim Busik, in his Samguk Sagi, lamented that the name of the steadfast commander of Ansi Fortress was unknown: However, at least two later Korean sources give his name as Yang Manchun. The Collected works of Master Dongchundang by Song Jungil, first compiled in 1768, includes the passage: "Someone asked, 'What was the name of the commander of Ansi fortress?' Jungil replied, 'It was Yang Manchun. He skillfully checked the army of Taizong and so might we very well call him "seonsu seongja". Furthermore, The Jehol Diary written by Park Ji-won in the 18th century includes the following: "When Yang Manchun, the master of Anshi-sŏng Fortress, shot an arrow and put out the eye of the Emperor Taizong of the Tang dynasty, the emperor assembled his army under the wall. This was not the signal for an immediate attack, but to demonstrate the Emperor's generosity in granting Yang Manchun one hundred p'il roll of silk, praising him for defending the Fortress successfully for his own Korean king." In time Yang Manchun came into general use as the name of the defender of Ansi Fortress.
In 642, Yeon Gaesomun killed King Yeongnyu and seized military control over the country. However, although Yeon had quickly gained control over the rest of the country, Yang Manchun refused to surrender Ansi fortress. After a lengthy siege and repeated unsuccessful attempts to storm the fortress, Yeon was forced to withdraw and allow Yang to keep his position as fortress commander. This proved to be to his advantage. In 645, Taizong led a campaign against Goguryeo. Some Goguryeo border fortresses fell early, but Tang was unable to reduce Ansi fortress. Goguryeo sent a force reported at 150,000 to raise the siege of Ansi fortress, but the force was unable to reach it. Despite its siege of Ansi, the Tang army was unable to force its capitulation. Taizong eventually ordered the construction of a large earthen siege ramp, which Yang instead captured and used as part of his defense. When winter approached, Tang forces were forced to withdraw. The siege of Ansi fortress is related in detail in the Samguk Sagi, Goguryeo vol. 9..
