Early in the morning of the first day of the seventh lunar month of the seventh lunar calendar of Xiande, seeing that the political attack did not achieve any significant results, Chai Rong gave up the plan of "surrendering the army without a fight", and personally led more than 20,000 siege troops of the Later Zhou and Han armies to line up in the south of Taiyuan City, preparing to break through Taiyuan City by force.

According to the usual tactics of the Later Zhou army, capturing a city was usually a three-step process. The first step was to use the ballistas, stone throwers and other long-range weapons of the "Shenji Army" to fire gunpowder packs on the city wall to disperse the defenders on the city wall and make it impossible for them to gain a foothold on the city wall, so that they could not observe the movements of the Zhou army under the city and make the necessary defensive preparations in time. The second step is to use artillery, ballistas, trebuchants and other long-range weapons to use gunpowder packs to maintain the suppression of the enemy troops on the city wall, and at the same time use gunpowder packs to bombard one or more sections of the city wall selected in advance, and use the powerful destructive power of firearms to collapse one or several sections of the city wall on which the enemy is leaning. The third step is also the Zuihou step, which is to send elite assault infantry and trench fillers, under the cover of the artillery fire of the "Shenji Army", to rush to the enemy's city. The trench fillers filled the moat under the enemy's city, and the elite assault infantry followed, killing the generals through the wall that was destroyed by the firearms of the "Divine Machine Army", completing the control of the city wall, creating conditions for the main infantry to enter the city and finally occupy the city.

In this three-step siege tactic, although the third step is to fill the moat with the trench soldiers, the elite assault infantry to occupy the gap in the city wall, and provide a passage for the main force of the enemy to enter the city -- in order to avoid accidentally injuring friendly troops, when the trench fillers fill the moat and the elite assault infantry occupy the gap in the city wall, the "Divine Machine Army" will no longer continue to carry out long-range bombardment, but can only use some flintlock muskemen to provide close fire support for these trench fillers and elite assault infantry, and suppress the enemy's counterattack. The burden of holding the gap until the arrival of their main forces fell on the shoulders of these elite infantry. However, the second of the three steps, the use of firearms to destroy the enemy's walls, is a prerequisite for the implementation of the most critical third step. Moreover, under normal circumstances, unless there is another "genius" general like Cao Jiyun, the Khitan Gu'an defender, who is almost self-taught in defending against firearms and attacking the city, as long as the city wall is bombarded by the artillery of the Later Zhou army, the defenders in the city will soon collapse, and there will be basically no suspense in the subsequent battles - this is reflected in the Later Zhou expedition to the Southern Tang Dynasty and the battles of Qinzhou and Longzhou.

The only thing that caused trouble and trouble to this tactic of the Later Zhou army was the first tough battle of the Battle of Youyun the year before, the Battle of Gu'an. If that battle hadn't been secretly supported by the crossing team, the Later Zhou army would definitely have suffered more under Gu'an City. As a general of this era, Cao Jiyun, the Khitan Gu'an defender, was able to rely on very limited information and the short shelling process when the Later Zhou army attacked Gu'an City for the first time, and quickly figured out the weaknesses and countermeasures of all the firearms of the "Shenji Army", which could not help but make the generals of the Later Zhou Army, including Xu Shao'an, secretly admire - if it weren't for Zhang Weixin's fact that he had seen Cao Jiyun's name in the history books of his previous life, he was afraid that the crossing team would treat the other party as a suspected traverser.

Speaking from the heart, the Later Zhou army was able to quickly conquer Gu'an, not because Cao Jiyun's coping tactics were problematic, but largely due to the sudden and rapid attack of the small detachment that entered Gu'an City through the secret tunnel, and as soon as the team and the defenders engaged, Cao Jiyun was killed by Zhou Lang and Xu Yong coldly. Otherwise, the battle of Gu'an is likely to continue for a while, and the Later Zhou army will have to pay even greater casualties.

It's just that there is only one "genius" like Cao Jiyun so far, and after the war, in order to maintain the advantages of equipment and tactics, the Zhou court deliberately downplayed the tragedy of the Battle of Gu'an, blurred the course of the Battle of Gu'an, and blocked the spread of the strategy and tactics used by Cao Jiyun in this battle. As a result, Cao Jiyun's methods of dealing with primitive firearms were passed on to some of the high-ranking Khitan generals through his letters to Xiao Siwen, and the rulers of other secession regimes and their generals did not know much about these strategies and tactics. In addition, the great victory of the crossing team armed in the later stage of the battle of Youyun made all parties shili's fear of firearms reach the extreme, and their hearts were full of fear for the "Shenji Army" of the Later Zhou Dynasty, which also used firearms - speaking of which, this is also a collateral consequence caused by the fact that the firearms used by the crossing team are deliberately blurred for the sake of secrecy. …,

It is precisely because of the fear of firearms in each separatist Shili, and the reality that the enemy army was almost invariably rapidly defeated under the blow of their own firearms in a series of previous battles, so this time, from Chai Rong, the Son of Heaven, to the ordinary soldiers of the Later Zhou and Han armies, they were all determined to win, believing that even if the Taiyuan city was deep and there were many defenders, it was only a matter of time before it was defeated in the face of the firearms bombardment of the "Shenji Army".

At the beginning of the attack on Taiyuan City on the morning of the first day of the seventh lunar month of the seventh lunar calendar of Xiande, the battle situation was indeed as expected by the soldiers of the Later Zhou Army, with the ballista and stone throwing troops of the "Shenji Army" projecting gunpowder bags on the city wall on the west side of Taiyuan City and inside and outside the city wall, the Northern Han defenders who were still waving flags and shouting above the city head, beating drums and building momentum, and the Zhou army under the city immediately became chaotic, threw away the flags and drumsticks in their hands, and fled to the city wall with their heads in their hands. In an instant, Taiyuan City, which was very lively before, was empty, and only a few defenders would occasionally show half of their heads from behind the battlements, hurriedly glance at the city, and then shrank back at a very fast speed.

Looking at the performance of the Northern Han defenders of Taiyuan City and the defenders of other captured cities, all the soldiers and generals of the Later Zhou Han Army under the city were holding a good show, very relaxed and waiting for the "Shenji Army" to carry out the second step of the siege step, blasting the wall of Taiyuan City open one or several gaps, and then rushing into it in one go, and capturing the puppet Han emperor Liu Jun, who did not know the height of the sky and refused to submit to everyone Zhou, and the group of Wenchen generals under him were captured in one fell swoop, and then happily returned to the capital Kaifeng.

The generals of the Later Zhou Dynasty and the Han Dynasty soldiers and even the monarchs and ministers of the Later Zhou court under the city were so confident that they did not take the Northern Han defenders in Taiyuan City into account at all, so that no one found that the city tower in the middle of the city wall that had been riddled and crumbling under the fierce bombardment of gunpowder bags was that the four buildings on the west side of Taiyuan City on the city wall were slightly higher than the battlements and the whole body was gray and white. Among the four gray-and-white buildings, twenty or thirty Northern Han defenders were taking turns to pass through the gaps in the battlements that were almost integrated with the gray-white buildings, vigilantly observing the every move of the Zhou and Han armies under the city.