|Revised Romanization||Yang Manchun|
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 refusal to surrender the fortress to invading Tang forces.
Whether "Yang Manchun" was his real name is unclear. Kim Busik, in his Samguk Sagi (Chronicles of the Three Kingdoms), lamented that the name of the steadfast commander of Ansi Fortress was unknown:
Emperor Taizong of Tang was a prominent and intelligent ruler not commonly seen. He ended disturbances like Tang of Shang and King Wu of Zhou, and he governed with reason like King Cheng of Zhou and King Kang of Zhou. When he commanded armies, he had infinite strategies and had no rival. But when he attacked east, he was defeated at Ansi. Therefore, the defender of Ansi must have been a hero and also an unusually brilliant man. However, his name was lost to history. This is like how the Yangzi stated, "The name of that great official from the Qi-Lu region [(i.e., modern Shandong)] is lost to history." This is lamentable.
However, at least two later Korean sources give his name as Yang Manchun. The Collected works of Master Dongchundang (동춘당선생별집, 同春堂先生別集) by Song Jungil (송준길, 宋浚吉), 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" (선수성자, 善守城者, "capable defender of fortresses"). Further, the Yeolha Ilgi (열하일기, 熱河日記), written by Park Ji-won, 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.
Involvement in the Goguryeo–Tang War
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 launched one of a series of massive winter attacks on 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.