However, not all of the Tang generals are brave heroes. When Li Shimin, Taizong of the Tang Dynasty, was stationed in the battle, Zhang Liang, the general manager of the Tang Pingyang Road March, led the Tang Dynasty Naval Army, and after the bearded guests and others captured Beisha City, they continued to advance to the northwest. Upon arrival at the city of Jian'an, Tang. The military barrier has not yet been strengthened, most of the soldiers went out to collect and graze, and the Goguryeo defenders in Jian'an City suddenly killed. Jun was a little frightened. Zhang Liang is a mediocre talent, usually timid and cowardly, when he saw the enemy army killed, he sat on the Hu bed, stared straight and did not speak, and was frightened like a wooden chicken. However, when the soldiers saw that his expression remained unchanged, they thought that he was calm and brave, and that the army's heart was a little settled, and the commander-in-chief Zhang Jinshu and others beat the drum to reorganize the army and attack the enemy. The Goguryeo defenders could not resist it, so they had to flee in defeat and flee into the city, and the infant city defended itself and did not dare to fight. Such a victory can also be called a joke in the history of warfare.

On August 24, Tang Taizong Li Shimin moved the military camp to the east of Anshi City to discuss the siege strategy with Li Tao and others.

Li Shimin, Li Tao and other generals carefully observed Anshi Castle and found that the area of this city was very large, and the city was very strong because of its high walls and thick walls. It has a series of very complete city defense systems, such as moats, suspension bridges, gate towers, urn cities, arrow towers, city towers, corner towers, enemy platforms, enemy towers, war sheds, female walls, battlements, and boarding roads, and the defense is very strong.

The tower of Anshi City is the city defense command post where the city lord Yang Wanchun sits; The urn city is a small city outside the big city gate to the acropolis gate, which is a closed space built outside the city gate, once the enemy enters it, it will be attacked by the city wall of the urn city, just like "catching a turtle in the urn"; The arrow tower is the building built on the gate hole of the urn city, there are arrow windows on the outer wall of the building and the left and right walls, the soldiers who defend the city can hide in the arrow tower and shoot arrows, can reduce their own casualties, condescending, and better shoot the enemy. The enemy tower is a castle tower built on the enemy platform of the city wall to garrison soldiers. In peacetime, you can take advantage of its protruding exterior and tall buildings to observe the enemy's situation and prevent the enemy from attacking the city in a roundabout way. In wartime, it can be fired from the front and between the left and right floors, and can be connected with the "war tent" on the city wall to weave a tight high-altitude fire network to snipe the enemy attacking the city. The enemy building is a two-storey building with heavy eaves on the top of the brick and wood structure, the building body is 9.22 meters high, and there is a pedestal built downstairs, and a cloister is set up around it. The door of the ground floor is inward, and the outer wall is open with three windows; The outer wall of the second floor has three holes in the arrow window, and there are no windows on the left and right. The enemy platform, also known as the pier platform, wall platform, and horse face, is the part of the wall that protrudes outward from the city wall, which can defend against the enemy on three sides. The distance between adjacent enemy platforms is 120 meters, and the crossfire is 60 meters - it is the effective range and killing range of ancient arrows, crossbows, flying hooks, throwing guns and other long-range and throwing weapons, once the enemy climbs the wall to attack the city, it can form a group of high-altitude dense cross fire networks outside the main city wall, kill the enemy under the city, make it difficult for the enemy to approach the city wall, and greatly improve the defense of the city.

The city lord of Anshi City is called Yang Wanchun, his people are brave, his soldiers and horses are excellent, and the terrain of the city is also extremely dangerous, when Mo Lizhi made a rebellion, Yang Wanchun did not accept Mo Lizhi's usurpation, so Mo Lizhi sent a large army to attack Anshi City but failed, so he had to acquiesce to Yang Wanchun's dominance in Anshi City.

Tang Taizong Li Shimin knew that Anshi City was a difficult bone to gnaw, and Yang Wanchun made up his mind to defend the city and never fight with Tang. Army frontal field, Don. It is very difficult for the army to capture the city of Anshi, so it is proposed to attack Jian'an in the west of She'an City, at this time the naval army led by Zhang Liang is also besieging Jian'an City, and the two armies are attacking "Jian'ande, then An'an City is in my belly"; However, Li Tao thought that if the west attacked Jian'an, it would be far from Tang. Liaodong City, the army's food base, was too far away, and if Goguryeo cut off our way back, the situation would inevitably lead to a crisis, so we insisted on "attacking Anshi first." In the end, Tang Taizong Li Shimin agreed to Li Tao's plan in line with the principle of employing people without doubt.

On 25 August, Li Shimin, Taizong of the Tang Dynasty, moved the military camp to the south of Anshi, cutting off the connection between Anshi and Jian'an. Then he ordered Li Tao to attack the city. Li Tao and others supported Gao Yanshou and other Goguryeo to surrender to the city of Anshi and recruited the soldiers in the city. But the city held on, and every time he saw Tang Taizong Li Shimin's banner, he would take advantage of the city to make noise and reject with bows and arrows. Tang Taizong Li Shimin was furious, and Li Tao took the opportunity to ask for Kecheng on the day of the man's execution. When this word spread into the city, the defenders were angry, and everyone fought to the death, so they could not be conquered for a long time.

At this time, the Goguryeo general Gao Yanshou offered advice: the Goguryeo general should be released to reunite with his wife in order to move the hearts of the defenders of Ancheng City; Then move the troops to attack the city of black bones, the defenders of the city are weak, and they can go to Xike. In the end, the army went south, and ping soil could be obtained at your fingertips. The generals also suggested that they should join forces with the naval army led by Zhang Liang, and strive to pull out the black bones, "cross the Yalu water, take the ping soil directly, and do it in this move." Tang Taizong Li Shimin was about to adopt this suggestion, but the eldest grandson Wuji tried his best to admonish him. He believed that if the troops were moved, the Goguryeo defenders of Jian'an and Xincheng would "follow behind", and our army would have to worry about the enemy. Therefore, he advocated breaking the city of An'an first, then taking Jian'an, and then driving forward, "this perfect strategy".

Tang Taizong Li Shimin then dispelled the idea of moving troops. The eldest grandson Wuji's suggestion was of course a foolproof strategy, but this made Tang. The army fell into the process of pulling out many "nails" established by Goguryeo one by one in a frontal battle, and the war was bound to be protracted. After the army has pulled out all the nails, how many troops can be left to attack the capital of Goguryeo? Obviously, according to this policy, it would be an impossible task to defeat Goguryeo in one fell swoop. In fact, all in all, it's still Don. The army is not enough to cause trouble, if it is Don. If there are more troops, why should Li Shimin, Taizong of Tang Dynasty, be stingy with those 5,000 people? And now you can divide your troops to attack Jian'an and the cities of Wugu, and attack more, so that you won't be trapped under the city of An.

On August 26, in the afternoon of the same day, the sound of pigs and chickens crowing was heard in the city of Anshi, and Li Shimin, Taizong of the Tang Dynasty, estimated that the Goguryeo defenders might attack the Tang camp at night, so he tightened his troops.

Sure enough, hundreds of Goguryeo people marched down the city in the middle of the night, and Tang Taizong Li Shimin personally galloped to the city, and the army attacked sharply, and the Goguryeo army killed dozens of people, and the rest could only retreat to the city.

The next day, Tang Taizong Li Shimin ordered Jiangxia Wang Daozong to build an earthen mountain in the south of Anshi City to force the city. The defenders of the city also increased their city, and the Tang. The army refused. The soldiers of both sides fought again and again, and every day it took six or seven rounds. Tang Dynasty. The soldiers used the cannon stones to destroy the forts, and the defenders of the city used wooden fences to plug the gaps.

Li Daozong injured his foot when he was building Tushan, and Li Shimin, Taizong of the Tang Dynasty, personally acupuncture for him.

The terrain of Anshi City is dangerous, strong and abnormal, there are many defenders, the defense is tight, and Yang Wanchun, the lord of Anshi City, also commands well. Tang Dynasty. The army attacked for five days in succession, but it was unsuccessful.

Li Daozong walked barefoot to the banner to ask for guilt, and Tang Taizong Li Shimin was pardoned for his merits in breaking Gaimu and Liaodong.

At this time, the relentless defense of Anshi City finally took Don. The army dragged into September, and the frost fell early in the eastern Liaodong region; The grass is dry and the water is frozen, and the military rations are about to run out, and it is difficult for the soldiers and horses to stay for a long time, Tang Taizong Li Shimin is anxious, is it possible that this expedition to Goguryeo will be abandoned halfway?

Tang Dynasty. In this eastern crusade, the army attacked 10 cities, including Xuansu, Hengshan, Gaimu, Momi, Liaodong, Baiyan, Beisha, Maigu, Yinshan, and Houhuang, and moved 70,000 people from Liao, Gai, and Yan into Shanhaiguan. A total of 40,000 enemies were annihilated, two of his generals were surrendered, 3,500 generals and the children of officials and chiefs, 100,000 soldiers, and dry rations were returned to the mainland. and 50,000 cattle and horses, as well as a large amount of grain. Tang Dynasty. The army itself lost nearly two thousand, and seven or eight out of ten of the war horses died. If he withdraws his troops and returns to China now, Li Shimin will also have a great gain. However, when they come to conquer Goguryeo again in the spring of next year, it is estimated that they have already caught their breath and may be even more difficult to deal with.