Yunyang City is not large, it has been broken by the army many times in more than ten years of war, and there are many obvious dividing lines on the city wall, and the walls on both sides of these boundaries are different from the old and new Cheng dù and Yan sè. Every time it is captured, the walls are damaged by the strict, and the occupiers will abandon them if they have no intention of defending them, and patch the walls if they intend to defend them. Due to the frequent wars, there is a constant need for new patches, and patches may be patched on patches, and sometimes Yunyang changes hands again before the patching work is even completed.

Therefore, the Yunyang city wall in front of you is like a beggar's clothes. On the vast land of the lake, all kinds of armies come and go, and many cities have suffered similar to Yunyang, the city has changed hands many times, and the city walls have been mended and repaired.

Yunyang is a small city with four city gates, and you can imagine that there are about two relatively wide roads inside, each connecting the two gates, intersecting at the city zhōngyāng, and the intersection will be where the yamen in Yunyang City is located. The four gates did not have the urn structure of the tall Kunming City, but simple towers were built to enhance the defense of the gates.

Although it is not clear the specific strength of the Qing army in the city, Yuan Zongdi and Liu Tichun estimate that there will be three or four thousand people. The strength of the Ming army was not strong enough to block all four city gates, so the Ming army only set up camp outside the city gate directly south, concentrated its soldiers here to threaten the city, and launched an attack on Yunyang to train its soldiers. In addition, half of the auxiliaries were drawn out and protected by a small number of soldiers to collect supplies in the suburbs.

The work of the Ming army to collect materials and move people gave Deng Ming the impression that he was close to the bandits, but he could not interfere, and there was no way to stop it. At a time when the Ming army itself was struggling to make a living, it was impossible to expect them to use gentle means to persuade the people to voluntarily go to the Three Gorges with them. If Deng Ming himself was an ordinary person, he would not want to go to the Three Gorges to become a serf and reclaim the military camp.

There was no moat outside Yunyang City, only a trench that was not too wide, so Yuan Zongdi and others saved the training process of digging ditches to divert water, and directly began to instruct their subordinates on how to efficiently fill the trenches, destroy the fortifications by the wall, and build siege equipment.

On the outside of the Yunyang city wall, there are many wooden stakes that have been driven into the ground, and Deng Ming has seen them in front of the city of Chóngqìng before, and knows that these wooden stakes are called "plum blossom piles". The defending side arranged these things in a staggered manner to prevent the enemy's ladders and carts from approaching the city walls. Like the walls of Yunyang, these wooden stakes on the ground are also old and new, and some of them are close to decay and cannot play the role of defense at all; Some of them are brand new and don't seem to have been nailed into the ground for a long time.

"The time for these wooden stakes to be nailed into the ground is obviously different," seizing an opportunity, Deng Ming pointed to the plum blossom piles that were both new and old, and asked Liu Tichun: "It looks like the difference between the front and back can be many years, right?" ”

"Mr. Deng is right." Although Liu Tichun doesn't come to Yunyang often, he is very clear about the situation here. He told Deng Ming that Hao Shaoqi had come to attack Yunyang many times, and if he hadn't come for a while, he would definitely go to Gucheng. Whether it is in Yunyang or under the city of Gucheng, Hao Shaoqi, like Liu Tichun and Yuan Zongdi, does not forget to take advantage of the opportunity to train the soldiers, and every time he will cause some damage to the plum blossom pile position in front of the city.

After the Ming army left, the Qing army would inspect the plum blossom piles under the city and fill in the gaps destroyed by Hao Shaoqi, so the wooden piles were both new and old. Those old and decaying wooden stakes were not bothered to be dug out and replaced, because they were accustomed to Hao Shaoqi's consistent style and knew that the other party would not storm the city.

Deng Ming saw that when the Ming army was conducting siege drills, the Qing army in the city was also conducting defensive drills, and when the Ming army destroyed the fortifications, the Qing army at the head of the city interfered with firearms and bows and arrows. However, the Ming army did not really want to attack the city, so they paid great attention to the protection of the soldiers, and would not take risks to destroy the fortifications, so the formation was very loosely arranged. Again, the defenders didn't really want to kill or injure the Ming army, the main purpose was to train the recruits, so the Qing army's sāo slashes had little effect. The siege lasted two days, and the Ming army only cut a dozen stakes and paid the price of a few wounded.

Since the time of Li Zicheng, the army has attached great importance to siege techniques, and Liu Tichun and Yuan Zong, the second person of Liu Tichun and Yuan Zong, as the eighteen cavalry of Shangluo, went to the world and attached great importance to these technologies. Pull out the stake in front of the city, build a ladder behind the camp, although it is not intended to really attack the city, but the entire Ming army camp is busy.

Not far from the city walls, the Ming army quickly piled up a mound.

"This is a must before the start of the cave attack," Liu Tichun led Deng Ming to inspect the mound, and the Ming army quickly began to dig the tunnel after piling up the mound: "The mound can't be too far away from the city wall, otherwise the tunnel will stretch too long, and the excavation will be laborious and time-consuming, and the possibility of failure will also be greatly increased." ”

The longer the tunnel, the worse it is, and the more spacious it is, the more spacious it needs to be dug, so Liu Tichun believes that the closer the beginning of the tunnel is to the city wall, the better. The mound was built to cover the excavators working below, and the defenders' more effective means of defense was to send men out of the city to attack the mound and block the entrance.

"It is said that the defenders of Yunyang will not come out to attack this mound, but we must not be guarded, in case they sneak attack, the sons below will be buried alive."

Liu Tichun told Deng Ming that how to defend against the enemy's sneak attack on the mound is also a knowledge. Because the mound is relatively close to the city wall, it is easy for the defenders to observe the deployment of the attackers around the mound, and when launching a counterattack, it will be more targeted. Of course, if the troops are abundant and the time is plentiful, and the attackers are able to dig the tunnels very wide, the mound may also be moved back a little to a safer distance.

This mound of the Ming army was located in the middle of the two city gates, at the corner of the city wall, so that no matter which gate the Qing army fought from, they had to walk a long way to reach the entrance of the tunnel. The position of the hanging horn also gave the Qing army the fewest shè strike positions and observation positions. If the Qing commando team planned to go down the city, it would be more difficult and easy to be discovered by the Ming army. Liu Tichun and Yuan Zongdi deployed defensive troops around the mound, and dug some communication trenches to facilitate the concealment of the defensive troops. At the same time, rotating jǐng troops were deployed in the rear, ready to move forward for reinforcements.

Deng Ming looked at the orderly deployment, knowing that these were all lessons learned from the camp in the past twenty years, and he didn't know how many soldiers' lives had been paid for it. Compared with cutting the wooden stakes next to the wall, digging tunnels is safer, which is more in line with Liu Tichun's idea of training soldiers and avoiding casualties. The main forces of the siege that broke into the camp were on this side of the mound, and the officers of each team took turns to go down to the tunnel to observe on the spot. Regarding the various defensive arrangements around the mound and their significance, Liu Tichun and Yuan Zong took the trouble to repeatedly explain to the young officers.

The other officers only memorized with their brains, while Deng Ming recorded them all in detail in his notebook. Deng Ming also asked about the previous battle examples, and asked what kind of experiences and losses made the camp have the idea of making these arrangements.

"There are two purposes for attacking caves, one is to dig tunnels into the city, and the other is to destroy the city walls. It is very difficult to attack the city from the tunnel, and the tunnel must be very wide, which can accommodate a large number of soldiers to enter the city quickly; For this purpose, it is not possible to pile mounds at the corners of the walls, otherwise the defenders will only have to build another inner wall at the inner corner of the city, which will not be very wide, and the road will be completely blocked. ”

Liu Tichun introduced Deng Ming's past experience, and Yuan Zongdi supplemented the explanation of the battle examples on the side, and Deng Ming was busy recording while listening.

Those who tried to enter the city through tunnels would choose to build a mound on the front of the city wall, which would be closer to the city gate. Because even if you succeed in penetrating the city through a tunnel, only one tunnel will not guarantee the rapid passage of the army, and the purpose of the cave attack into the city is to cooperate with the frontal siege troops to try to capture and open a city gate.

And digging tunnels at the corners of the city walls, experienced guards knew at a glance that the attackers' intentions were to dig the foundations of the city walls. After digging to the corner, the attackers did not dig all the way through the wall, but kept digging deeper, and at the same time moved some sturdy wooden piles into the tunnel, and after removing the soil from the foundation, they used these stakes to support the foundation of the wall above. When a section of the wall was completely hollowed out, the personnel were evacuated and the wooden piles that supported the foundation of the wall were set on fire, causing the wall to collapse.

"The key is ventilation, if the tunnel is too narrow and not ventilated, you can't burn the stakes." Liu Tichun believes that in the face of this kind of offensive of digging the corners of the wall, the best defense is still to take the initiative to destroy the entrance of the tunnel, and in the face of this kind of attack, the ventilation means of the tunnel are also related to the life of the soldiers below: "The time to dig the tunnel is very long, and it is impossible to hollow out the foundation of the wall and install enough wooden stakes. If the walls are thicker, more stakes are needed, the excavation time is longer, and the tunnels need to be dug wider in order to burn more stakes. During this period, it has always been possible to be attacked by the enemy out of the city, as long as the enemy successfully breaks through to the entrance of the tunnel, as long as they are allowed to control the entrance of the tunnel for a quarter of an hour, or even a pillar of incense, they can seal the entrance with a soil bag, and those who are still inside will be suffocated. ”

"The most important thing is not how fast you dig, but how to protect the mound." Yuan Zongdi deeply understood this, in his past military career, especially when the camp was still lacking in siege experience during the Chongzhen period, the cave attack on the camp would always fail because the defenders attacked the mound. Even if reinforcements arrived to expel the enemy, they could not dig out all the soil bags that were blocked in the cave for a while, and when they opened the hole again, there were no living people inside.

"Later, when we started digging tunnels, we would have a lot of bamboo poles ready before we started." This time, Yuan Zongdi and Liu Tichun also prepared a lot of long thick bamboo poles, opened them all inside, and inserted many bamboo poles into the ground when digging tunnels: "Sometimes, even if you defend carefully, you will still be attacked by the dead soldiers sent by the enemy to the edge of the mound, and they will seal the entrance to the hole. When it's time to burn the wooden piles that support the foundation of the wall, having these bamboo poles to breathe can also make the fire burn longer. ”

"Wouldn't this reveal the direction of the tunnel?" Deng Ming asked with some confusion: "Besides, what if the enemy also blocks the bamboo pole when he blocks the entrance of the cave?" ”

"You can guess where the tunnels are going into the city, so it's much easier to put some fake bamboo poles on the ground to confuse them than to dig the tunnels. We won't give the enemy a lot of time, how can we make them block holes and cut bamboo? Yuan Zongdi pointed out that if such a thing happens, it can only mean that the attackers have completely lost control of the ground, and if the army on the ground is defeated, then the people underground will die.

Deploying defenses, inserting real and false ventilation bamboo poles, these things Yuan Zongdi and Liu Tichun did very carefully, and how to dig and transport soil efficiently The two of them also taught by word and deed. But they didn't really want to hollow out Yunyang's wall foundations, because that was never something that could be done in the short term. There are both proactive countermeasures and passive defensive means in the city. For example, new walls were built in the city to plug the gaps that had arisen due to the collapse of the walls. Or dig a canal inside the wall and fill it with water when the attacker is ready to burn the pillars. Either way of dealing with it takes manpower and time, but it is still less than the amount of work required to dig out the foundation of the wall. Yuan Zongdi and Liu Tichun could not predict what measures would be taken in the city, and counterattacking out of the city and flooding the tunnels could cause great losses to the attackers.

After the tunnel was dug under the foundation of the Yunyang wall, Liu Tichun and Yuan Zongdi planned to call it a day.

Now that the excavators have been able to experience the solid foundation of the wall above the tunnel, and have learned how to judge the position of the surface at the end of the tunnel, and have achieved all the training purposes, there is no need to carry out the work of widening and placing the wooden piles later, because the work is huge and time-consuming. As for how to place the wooden stakes in the tunnel, you can practice in other sections, and there is no need to really run under the wall base to practice.

During this period, Liu Tichun and Yuan Zongdi piled up mounds elsewhere, planning to dig a few more tunnels and let their subordinates exercise their skills while the iron was hot. The soldiers who collected grain, grass and population around him had not yet returned, and Hao Shaoqi from Gucheng also sent a letter to him, saying that he had just started sweeping and needed the Ming army in Yunyang to help him contain him for a while.

But at this time, Deng Ming stood up and expressed his opinion.

Deng Ming has always been humble in learning before, and has never questioned any decision of Yuan Zongdi and Liu Tichun. Now the tunnel has reached the bottom of the wall, although it is only a few meters wide and only one meter high, but as a modern person, Deng Ming does not understand why he does not use gunpowder to blow it up.

"Blowing up the city with gunpowder?" Yuan Zongdi and Liu Tichun shook their heads together: "Gunpowder can't blow up the city." ”

"Why?" Deng Ming felt that this assertion violated the common sense he knew.

In this era, there was really no common sense of blasting walls with gunpowder. Not only not, but there are examples of failure, which Yuan Zongdi and Liu Tichun have witnessed with their own eyes.

"When the second attack was opened......

Since it was Deng Ming who asked, Liu Tichun talked about the past. When the second attack was opened, Li Zicheng already had hundreds of cannons in his hands and handed them over to Liu Zongmin to use to attack the city wall. Liu Zongmin used these cannons to bombard Kaifeng City for several days and nights, but he still failed to blast out of the city wall, and there was not even any sign of a breach in the city -- because the caliber of these cannons captured by Li Zicheng was too small to have the ability to attack the city.

In a hurry, Liu Zongmin continued to increase the amount of charge, and as a result, there were a large number of explosions, not only was he still helpless against the Kaifeng city wall, but he caused great casualties to his own people, and also lost a lot of artillery. However, the explosion reminded Liu Zongmin, and he had an idea and ordered a hole to be dug in the Kaifeng city wall, and then filled with a large amount of gunpowder.

Yuan Zongdi remembered Liu Zongmin's original words: "Let the Kaifeng city wall explode like a cannon." ”

And the result?

The result was that after the gunpowder was ignited, the big hole filled with gunpowder in the Kaifeng city wall set off fireworks, which was very spectacular and beautiful, and the invading troops within a radius of several miles could see it clearly. After the fireworks are set off, what should the city wall be, and the hole that Liu Zongmin sacrificed and dug out with great sacrifice and hard work is still how big it is.

"Gunpowder can't take a city. Cannons had to be cast first, heavy thousands of pounds of cannons, and then the walls of the city could be blasted with cannons. If you encounter thicker walls, you need heavier cannons. This is the opinion of Yuan Zongdi and Liu Tichun, they do not have the ability to cast such cannons, so they do not have the ability to attack the city.

"Then why did the cannon blow up?" The argument that black powder could not be used to blast was the most ridiculous military opinion Deng Ming had ever heard, and he immediately asked rhetorically.

Yuan Zongdi said that he did not know, and Liu Tichun thought that this was of course because "fire can overcome gold", and the walls were earthy and could not be overcome by gunpowder.

"When we were in Kunming, we lit the powder magazine and there was an explosion, and the walls of the warehouse were not dirt. Isn't it also fired? ”

Liu Tichun said that he did not know the five elements of Shengke, so he could not answer such a profound question. However, he pointed out that perhaps the word "Ming" in Kunming belonged to fire, which increased the power of gunpowder.

Yuan Zongdi was inspired by this and thought that it should be because Zhu Ming belonged to the fire virtue, and it was not surprising that the power of gunpowder had multiplied around the third prince, the fire virtue king.

Recalling his junior high school chemistry knowledge, Deng Ming estimated that black powder would produce a large amount of carbon dioxide and nitrogen after reaction, and if it was in a confined space and the container could not withstand the pressure, it would explode. Think about the fireworks and firecrackers that I have seen in the past, if there is a gap in the packaging, fireworks will be generated, and firecrackers that do not release air pressure will explode. In fact, it is similar to what Deng Ming thought, the volume of gas is nearly 10,000 times the original volume, and the gas of more than 1,000 degrees can produce extremely high air pressure in a confined space.

"Black powder can explode, as long as it is ......" After some thinking and association, Deng Ming became more confident when he spoke again.

Liu Zongmin's failure was only because he didn't understand junior high school chemistry and didn't create a confined space.