Emperor Taizong sent Yan Lide to Hongzhou (now Nanchang, Jiangxi Province), Raozhou (now Shangrao, Jiangxi Province) and Jiangzhou (now Jiujiang, Jiangxi Province) to build 400 warships, and appointed Youzhou (now Beijing) and Qidan and Hongjun troops loyal to the Tang Dynasty to command Yingzhou to conduct a tentative attack on Goguryeo. Yuan Gai Su Wen immediately sent a special envoy to the Tang Dynasty to make peace, so as to avoid the escalation of the war between the two sides. However, Emperor Taizong did not accept Goguryeo's tribute, but detained them in the future, accusing them of betraying the king and conspiring with the regicide. In the winter of 644, Emperor Taizong left Chang 'an with most officials and Crown Prince Li Zhi, and began to March slowly to the border between Tang and Koguryo. Fang and Li Daliang stayed in the capital Chang 'an. Li Shimin first arrived in Luoyang, where he made further preparations for several months. On New Year's Day in 645, Emperor Taizong appointed Sean as the general manager of Pyongyang Road March, Changhe and Zuonan as the deputy general managers of Pyongyang Road March, and Ran Rende, Liu, Zhang Wengan, Pang Xiaotai and Cheng Mingzhen as the general managers. He led 43,000 troops from Laizhou and crossed the Yellow Sea to Pyongyang in 500 warships. At the same time, Li Shiji was the chief officer of Liaodong Road, Li Daozong, the king of Jiangxia, was the deputy chief officer of Liaodong Road, and James Zhang, Chi, Lu Bo, Jiang Hangben, Qu Zhisheng and Wu Heikai were the chief officers, leading 60,000 troops to March into Liaodong by land. Emperor Taizong was full of confidence in the victory of this war. He believes that Yang Di failed to defeat Goguryeo because Yang Di was too cruel to his own people, while Goguryeo cherished his own people. Emperor Yang Di used a rebel army to fight against Koguryo's joint army, so it was impossible to win. Now all this has changed. First of all, this war is a big country fighting a small country. Secondly, this war is a crusade against traitors by the teacher of justice. Third, this war is a well-organized army attacking another chaotic army. Fourth, this war is an energetic army attacking another exhausted army. In the end, the war is an army with high spirits attacking another army with complaints. Therefore, Tang's attack on Koguryo is a shoo-in. In the spring of 645, Emperor Taizong began to leave Luoyang to attack Koguryo. Xiao Yu was left to guard Luoyang. After arriving in Dingzhou (now Baoding, Hebei Province), Emperor Taizong asked Li Zhi to stay there to take charge of the logistics tasks of the troops. Li Zhi stayed in Dingzhou with Gao Shilian, Liu Yue, Ma Zhou, Zhang Hangcheng and Gao Jifu. Li Shimin with Sun Chang mowgli, Cen Wenben, Yang Shidao, Wei Chijingde, Liu Hongji, Yan Lide and other ministers to move on. Cen Wenben died in Youzhou. At the same time, Li Shiji and Li Daozong crossed the Liaohe River with Li Shimin and captured Gaimou (now Fushun, Liaoning) in the summer of 645. At sea, Sean has crossed the Bohai Sea and captured Beisha (now Dalian, Liaoning). In order to deter Goguryeo, Sean sent an advance fleet to the mouth of the Yalu River, but he did not go further to Pyongyang as first requested by Emperor Taizong. Soon, Li Shiji and Li Daozong surrounded Liaodong (now Liaoyang, Liaoning), which Yang Dijiu could not capture, and captured Liaodong when Emperor Taizong arrived. Sun Daiyin, Duke of Bai Yancheng, surrendered. Then Li Shimin began to March into Anshi City (now Anshan, Liaoning). In North Korea, Gao Yanshou, Koguryo, Gao Shuai, 150,000 soldiers saved Ancheng, and Tang Jun broke it in Huashan. There are 36,800 people in Gao Yanshou and Gao Shuai. Please surrender. In this battle, Xue put on a distinctive white armor and fought bravely with a painted halberd. After that, he was appreciated by Emperor Taizong and became a general of the Tang Dynasty. [Editor] Before the Anshi War attacked Anshi City, Emperor Taizong learned that Anshi City was difficult to attack, and the name of Anshi City Lord Yang Wanchun (both Chinese and Korean history books lost the name of Anshi City Lord, and Korean folklore named Yang Wanchun). ) Wit and courage have a strong defense. After Yuan was changed to Koguryo Regent, Yang Wanchun refused to accept Yuan as Regent. Su Yuan changed to send troops to attack Anshi City, but failed, so he had to let Yang Wanchun stay in office. Emperor Taizong planned to attack the easier Jian 'an City (now Yingkou, Liaoning) first. So, take Jian 'an City on the south side of Anshi City, and Anshi City is broken. Li Shiji expressed opposition to this. He thought that if Emperor Taizong attacked Jian 'an City first, Anshi City would cut off Tang's supply line from Liaodong and put Tang in a passive position. So Emperor Taizong decided to besiege Anshi City first. When the troops of Emperor Taizong and Li Shiji arrived in Anshi City, the defenders of Anshi City saw the flag of Emperor Taizong and swore on the wall. Li Shimin was furious. Li Shizhen asked Emperor Taizong to take Anshi City and kill the people in it. [6] This made it more difficult for the defenders of Ancheng to resist Tang Jun, so that Li Shiji could not take Ancheng for the time being. One day, Emperor Taizong heard the sound of killing chickens and pigs from Anshi City. So he told Li Shiji that Koguryo people might be entertaining the garrison and preparing for a surprise attack. Li Shiji was prepared for Koguryo's surprise attack at night. As expected, An Shicheng really raided Tang that night. However, Li Shimin, who served as a guard for a long time, personally led the troops to repel Goguryeo's attack. At the same time, Li Daozong began to build heaped-up mountains in the southeast of Anshi City to attack Anshi City. To this end, Anshi City is also constantly heightening the southeast wall. After 60 days of confrontation between the two sides, the heaped-up mountains in Li Daozong are high enough to see the inside of Anshi City. Li Daozong and his men Fu Fuai climbed to the top of Tushan Mountain. Suddenly, the mound mountain collapsed and fell on the wall of Anshi City. As a result, the wall of Anshi City collapsed. Fu Fuai went AWOL at this time. Koguryo took advantage of the chaos to capture the earth mountain and used it as a defensive weapon of Anshi City. In a rage, Emperor Taizong publicly executed Fu Fuai and ordered a crazy attack on Tu Shan. But I didn't take it off after playing for three days. Li Daozong then confessed to Li Shimin barefoot. But Li Shimin forgave him. With the approach of winter, the supply of Tang began to be in short supply. On September 18, 645 (65438+ 13 10), Emperor Taizong ordered the retreat. [Editor] When Li Shimin retreated from Liaodong, he forced the residents of Liaodong to move to the territory of the Tang Dynasty. According to the records in Zi Jian and The History of the Three Kingdoms, during the Tang Dynasty, about 70,000 Koguryo people were forced to move from Liaodong to the Tang Dynasty. When Li Shimin crossed the Liao River, he met a quagmire. 65438+100000 people filled the mud, and Tang Dajun crossed the Liaohe River. Some soldiers froze to death while waiting in the cold winter. Emperor Taizong regretted waging this war, saying that if Wei Zhi were still alive, Wei Zhi would definitely dissuade him from waging this war. [7] After his death in 643, Emperor Taizong once suspected that he had formed a clique with Hou and Du and destroyed his tombstone. After confession, Li Shimin ordered the reconstruction of Wei Zhi's tombstone, and summoned and rewarded Wei Zhi's widow and children. /kloc-On the way from Dingzhou to Bingzhou (now Taiyuan, Shanxi Province) in February, Li Shimin fell ill and returned to Chang 'an after several months of recuperation in Bingzhou. After Emperor Taizong returned to Chang 'an, he handed over the general political affairs to Prince Li Zhi. Korea/KLOC-Poems and notes from the 0/8th century onwards claimed that Emperor Taizong's eyes were injured by an arrow. There is no basis in history for the injury statement.