Legend has it that Li Shimin came to Dalian when he was conquering Goryeo. It is said that the place name Malanzi was the place where Li Shimin’s army raised horses.
Taizong of the Tang Dynasty sent Yan Lide to Hongzhou (now Nanchang, Jiangxi), Raozhou (now Shangrao, Jiangxi) and Jiangzhou (now Jiujiang, Jiangxi) to build 400 warships, and moved Youzhou (now Beijing) and Khitan and Mohe troops loyal to the Tang were assigned to the commander of Yingzhou to conduct a tentative attack on Goguryeo. Yeon Gaesumun immediately sent a special envoy to pay tribute to the Tang Dynasty to make peace, so as to avoid the escalation of the war between the two sides. However, Tang Taizong did not accept the tribute from Goguryeo. Instead, he detained the envoys and accused them of betraying King Rongliu and conspiring with the regicide. In the winter of 644, Tang Taizong left Chang'an with most officials and Crown Prince Li Zhi and began to slowly march towards the border between Tang and Goguryeo. Fang Xuanling and Li Daliang stayed in the capital Chang'an. Li Shimin first arrived in Luoyang and made further preparations there for several months. Around the New Year of 645, Emperor Taizong of the Tang Dynasty ordered Zhang Liang to be the general manager of the Pyongyang Road march, Chang He and Zuo Nandang to be the deputy general managers of the Pyongyang Road march, and Ran Rende, Liu Yingxing, Zhang Wenqian, Pang Xiaotai, and Cheng Mingzhen to be the general managers, leading 43,000 troops. The troops set off from Laizhou on 500 warships and crossed the Yellow Sea towards Pyongyang. At the same time, Li Shiji was appointed as the general manager of the Liaodong Road march, and Li Daozong, the king of Jiangxia, was the deputy manager of the Liaodong Road march. Zhang Shigui, Zhang Jian, Zhi Shisi Li, Qibi Heli, Ashina Mishe, Jiang Xingben, Qu Zhisheng, Wu Heita was the commander-in-chief of the march and led 60,000 troops to march from land to Liaodong. Tang Taizong was full of confidence in the victory of this war. He believed that the reason why Emperor Sui Yang failed to defeat Goguryeo was that Emperor Sui Yang was too cruel to his own people while Goguryeo cherished its own people. Emperor Sui Yang used rebel troops to fight Goguryeo's united army, so it was impossible to win. Now all that has changed. First of all, this war is a big country fighting a small country. Secondly, this war is about the righteous army fighting against the rebellious thieves. The third war is a well-organized force attacking another disorganized force. The fourth battle was an energetic force attacking an exhausted force. In the end, the war pitted one unit with high morale against another unit with a lot of complaints. Therefore, Tang was sure of victory in attacking Goguryeo this time. In the spring of 645, Tang Taizong began to leave Luoyang to attack Goguryeo. Xiao Yu was left to guard Luoyang. After arriving in Dingzhou (now Baoding, Hebei), Emperor Taizong asked Li Zhi to stay there and be responsible for the logistics tasks of the army. Along with Li Zhi, Gao Shilian, Liu Jie, Ma Zhou, Zhang Xingcheng and Gao Jifu stayed in Dingzhou. Li Shimin continued to move forward with ministers such as Changsun Wuji, Cen Wenwen, Yang Shidao, Yuchi Jingde, Liu Hongji, and Yan Lide. Cen Wenwen died of illness in Youzhou. At the same time, Li Shiji and Li Daozong had crossed the Liaohe River with Li Shimin and captured Gaimou (now Fushun, Liaoning) in the summer of 645. By sea, Zhang Liang had crossed the Bohai Sea and captured Beisha (now Dalian, Liaoning). In order to frighten Goguryeo, Zhang Liang sent an advance fleet to the mouth of the Yalu River, but did not proceed further to Pyongyang as Tang Taizong first requested. Soon, Li Shiji and Li Daozong surrounded Liaodong (today's Liaoyang, Liaoning), which Emperor Sui Yang had been unable to capture for a long time, and captured Liaodong when Emperor Taizong of the Tang Dynasty arrived. Sun Daiyin, the lord of Baiyan City, asked for surrender. Then Li Shimin began to march towards Anshi City (now Anshan, Liaoning). In the northern part of Goryeo, Gao Yanshou, Gao Huizhen, Goguryeo, and Mohe soldiers rescued Anshi with 150,000 soldiers. The Tang army was defeated in Huashan. Gao Yanshou, Gao Huizhen, and 36,800 people surrendered. In this battle, Xue Rengui put on white armor that was different from others and fought bravely with Fang Tian's painted halberd. Since then, he was appreciated by Taizong and became a general of the Tang Dynasty. [edit] Battle of Anshi City Before attacking Anshi City, Emperor Taizong of the Tang Dynasty learned that the terrain of Anshi City was difficult to attack, and the lord of Anshi City, Yang Wanchun (the name of the lord of Anshi City was lost in both Chinese and Korean history books. According to Korean folklore, this His name was Yang Wanchun. He was resourceful and brave and had a strong defense force. After Yeon Gaesumun took over the regency of Goguryeo, Yang Wanchun refused to accept the regency of Yeon Gaesumun. Yuansu Gaiwen once sent troops to attack Anshi City, but failed, so he had to let Yang Wanchun continue to serve in his post. Tang Taizong planned to attack Jian'an City (today's Yingkou, Liaoning), which was easier. In this way, taking Jian'an City south of Anshi City, Anshi City will be defeated without attacking. Li Shiji objected to this. He believed that if Emperor Taizong of the Tang Dynasty attacked Jian'an City first, Anshi City would cut off the Tang Dynasty's supply line from Liaodong and make the Tang Dynasty passive. So Tang Taizong decided to besiege Anshi City first. When the troops of Tang Taizong and Li Shiji arrived at Anshi City, the defenders of Anshi City cursed loudly on the city wall when they saw Tang Taizong's flag, and Li Shimin was furious.
Li Shiji then asked Emperor Taizong of the Tang Dynasty to capture the city of Anshi and kill all the people in the city. [6] This made the defenders of Anshi City fight harder against the Tang army. In this way, Li Shiji was unable to capture Anshi City for a while. One day, Emperor Taizong of the Tang Dynasty heard the sound of chickens and pigs being slaughtered in Anshi. So he told Li Shiji that the Goguryeo people might be entertaining the defenders at a banquet to prepare for a raid. Li Shiji then made preparations for the Goguryeo army to raid at night. As expected, Anshicheng really launched a surprise attack on Tang that night. However, Li Shimin, who was prepared for it, personally led his troops to repel Goguryeo's attack. At the same time, Li Daozong began to build a mountain in the southeast of Anshi City for attacking Anshi City. For this reason, Anshi City also continued to heighten the southeast wall. After the two sides faced off like this for 60 days, Li Daozong's earth mountain was already high enough that he could see the inside of Anshi City. Li Daozong and his subordinate Fu Fuai climbed to the top of the mountain. Suddenly, the earth mountain collapsed and fell on the wall of Anshi City. The city wall of Anshi City also collapsed. Fu Fuai left his post without permission at this time. Goguryeo took advantage of the chaos to launch an offensive and occupied Tushan and turned it into a weapon for the defense of Anshi City. In anger, Emperor Taizong publicly executed Fu Fu'ai and ordered a crazy attack on Tushan. But after three days of fighting, I still couldn't get it. Li Daozong then went to Li Shimin barefoot to plead guilty. But Li Shimin forgave him. As winter approached, Don's supplies began to run low. On Guiwei Day, September 18, 645 (October 13), Emperor Taizong of the Tang Dynasty ordered a retreat. [edit] Retreat When Li Shimin retreated from Liaodong, he forced the residents of Liaodong to move to the Tang Dynasty. According to records in "Zizhi Tongjian" and "Historical Records of the Three Kingdoms", about 70,000 Goguryeo people were forced to move from Liaodong to the Tang Dynasty. When Li Shimin was crossing the Liao River, he encountered a quagmire. After 10,000 people were used to fill the swamp, Tang's large army passed through the Liaohe River. Some soldiers froze to death while waiting in the cold winter. Tang Taizong regretted launching this war and said that if Wei Zheng was still alive, Wei Zheng would definitely dissuade him from launching this war. [7] After Wei Zheng died of illness in 643, Emperor Taizong of the Tang Dynasty suspected that he had formed a party with Hou Junji and Du Zhenglun, and destroyed Wei Zheng's tombstone that he had personally written. After repenting, Li Shimin ordered the reconstruction of Wei Zheng's tombstone and summoned and rewarded Wei Zheng's widow and children. In December, on the way from Dingzhou to Bingzhou (now Taiyuan, Shanxi), Li Shimin fell ill with carbuncle. He recuperated in Bingzhou for several months before returning to Chang'an. After returning to Chang'an, Emperor Taizong of the Tang Dynasty handed over general political affairs to Prince Li Zhi. Poems, essays, and novels written after the 18th century in Joseon state that Emperor Taizong of the Tang Dynasty suffered an arrow wound in his eye. The theory of injury has no historical evidence