Although Deng Ming is full of confidence, Liu Tichun is still skeptical. In his opinion, the power of gunpowder was only enough to push an iron ball projectile out of the barrel of the cannon, and it was inconceivable to blow up a wall several meters thick; Yuan Zongdi also knew the lesson of Liu Zongmin's failure, but he was inclined to give it a try. He felt that the battle of Kunming seemed to prove that the third prince had a special promoting effect on the fire, and according to Zhou Kaihuang's description of the explosion of the Kunming arsenal, it seemed that the third prince had a range of effects several miles in diameter, and the power of gunpowder could be greatly improved in this range.

As a modern person, Deng Ming took it for granted that blasting with gunpowder was carried out. In his original world, this tactic would not be applied on a large scale until the Taiping Heavenly Kingdom, most notably Yang Xiuqing's attack on Nanjing. The city wall of Nanjing was built by Zhu Yuanzhang, the wall base is 15 meters thick, more than 10 meters high, and it is impregnable. At that time, Lu Jianying, the governor of Liangjiang in the Manchu Qing Dynasty, had only 5,000 men in his hands, and he dared to rely on the city wall of Nanjing to resist the Taiping army of hundreds of thousands, claiming to be one million - Lu Jianying believed that the city of Nanjing was strong, and Zheng Chenggong, who had a large number of artillery in the early Qing Dynasty, had no choice but to use it, and it was not a problem to defend against the Taiping army.

At the beginning, the Taiping army was really helpless, although the strength of the Qing army in the city was 100 times that of the Qing army, it was still unable to break through the city defense. The Taiping army had concentrated artillery on the Nanjing city wall day and night, but the dense cannonballs were blocked by the fifteen-meter-thick city wall, and could only cause limited damage to the buildings on the city tower. Later, Yang Xiuqing dug a tunnel under the foundation of the Nanjing wall, filled the coffin with black powder, closed the tunnel and blasted it, blowing down the almost impregnable Nanjing city wall, thus seizing the city.

Deng Ming originally built a wooden container, but Yuan Zongdi and Yang Xiuqing coincided, saying why bother, wouldn't it be necessary to dig up a coffin?

After the soldiers found a few fairly sturdy coffins from the mass graves, Deng Ming picked the one that looked the most sturdy. The plan of the Ming army was to first transport the empty coffin into the tunnel, dig a hole in the wall base of Yunyang according to the size of the coffin, and then pour the gunpowder out of the bag and put it in the coffin and stir it evenly.

Deng Ming always felt that it was immoral to dig up the grave and take the coffin, but looking at Yuan Zongdi's indifferent appearance, Deng Ming knew that persuasion was useless, but he was thinking in his heart that if the blasting could be successful, he must make his own containers in the future. Liu Tichun watched the soldiers' preparations from the sidelines, still not believing that this trick would work. After all, I have never heard of a successful precedent, only the lesson of Liu Zongmin's failure, and Liu Tichun does not believe that such a light of gunpowder can play a big role.

At present, no one else knows about this tactic except Deng Ming, let alone the importance of enclosed space, so Deng Ming took his personal guards to personally inspect the gap under the wall foundation.

Taking advantage of Deng Ming's departure, Liu Tichun complained to Yuan Zongdi: "Even if this coffin is full, at most it will be ten pockets of gunpowder, right?" If it is used to fire how many cannons can be fired, can these cannonballs blast the wall out of the gap? It would be nice to be able to knock off a layer of skin. Liu Tichun still felt that gunpowder could only push the projectiles of the cannon, even if all the gunpowder in the whole army was used to make shè projectiles, it would not be able to smash the city wall of Yunyang, so of course some of the gunpowder could not be used, not to mention that there was not even an iron ball.

"Didn't you say that Kunming has the word 'Ming', which will be prosperous?" Yuan Zongdi felt that there was no need to go against Deng Ming, since the siege of the city, the third prince has been studying seriously, never pointing fingers, and now he proposes the only one to build yì and is full of confidence, it is not good to categorically refuse: "Doesn't this Yunyang also have the word 'yang', just as prosperous." Besides, there is Mr. Deng, the three hundred years of fire virtue of the Emperor Ming, is that a joke? ”

Liu Tichun just complained casually, he and Yuan Zongdi had similar ideas, since Deng Min insisted on letting him try, and even if he failed, they would never blame Deng Ming for wasting gunpowder and time, but would definitely comfort him.

While the Ming army was digging the foundation of the wall below, the Qing army in the city was digging a canal behind the wall. The defenders of Yunyang did not think that the Ming army would attack strongly, so they did not plan to go out of the city to counterattack the mound, but chose to dig a canal to deal with it. The excavation speed of this canal was not very fast, and the Qing army believed that according to the normal progress, it would take many days for the Ming army to hollow out the wall foundation, at least for now the defenders have not seen the Ming army transport the wooden stakes into the tunnel. However, the work that should be done still has to be done, in case the Ming army can't think of it, and it really wants to dig up the city wall of Xunyang, the Qing army guards will immediately flood the tunnel with water and give the Ming army a look.

When the Qing garrison dug the ditch step by step, he did not know that the Ming army's siege preparations were almost complete at this time, not after the dozen rì he expected.

The coffin used for blasting was already filled with black powder, and Deng Ming needed to test the fuse before sealing it inside the wall base. The best fuse material to use is undoubtedly black powder, which does not require any air to react. In order to prevent the gunpowder of the fuse from being cháo, Deng Ming made a long belt of tarmac-brushed cotton cloth and filled it with gunpowder.

After burying a bag full of gunpowder in the soil and testing it, and confirming that it could serve as a fuse, Deng Ming ordered the coffin to be stuffed into the hole dug out, and he himself was responsible for sealing it in the tunnel. The section of the Yunyang city wall that was chosen to be blasted is about three meters wide, and the base of the wall is close to five meters. The hole dug by the Ming army was almost four meters deep, and the coffin was placed directly below the city wall. A hole was made in the coffin board facing outward, two fuses were placed for safety, and the hole began to be filled.

The materials used consisted of a large number of stone bricks, with Deng Ming first building one wall, then pasting a layer of earth, and then starting to build a second wall; The bricks of the lower wall and the bricks of the upper wall are staggered, and then a layer of soil is pasted...... Layer after layer. Deng Ming was afraid that the seal would not be good, and the soil layer would be sandwiched between the layers, and he didn't know how many walls were built in the end, anyway, there were countless of them. The dug tunnel was blocked by a small half of the brick wall, and the sealing layer was probably more than ten meters wide, if it wasn't for the fuse being long enough, Deng Ming would have wanted to build a few more walls.

After arranging the stone bricks, Deng Ming was still worried that the sealing layer would loosen and the guide would fail to explode, so he used a few large logs to resist the outermost wall.

While Deng Ming was in full swing to carry out the sealing work, the Yunyang guard general curiously observed the movements of the Ming army at the head of the city. When he saw the Ming army carrying stone bricks into the tunnel, the Qing general was puzzled: Is this to help me repair the foundation of the wall?

Although transporting wood into the tunnel was a normal step for cave attack, it also looked very strange in the eyes of the Qing general, who was sure that the Ming army could not have dug a large enough cave so quickly, and now transporting wood into it would not do any other benefit than causing trouble to excavate and transport the earth.

Under normal circumstances, transporting timber into the tunnel is also with digging and transporting, whenever a place is hollowed out, a piece of wood is used to support the wall foundation, it is impossible to dig in one breath and then transport the timber into it at the same time, because then the wall foundation will have already sunken, crushing the people digging inside. In the end, the Qing army guards felt that the wood transported into the tunnel by the Ming army did not seem to be suitable for use as supporting columns, and the Ming army did not continue to transport a few after transporting them, so they obviously gave up.

"Humph! Even if it is military training, it must be done seriously to be effective. The Qing generals sneered at the Ming generals under the city. He didn't understand what the Ming army was doing to transport bricks until the end, but he concluded that the enemy was still training the team, and the training was carried out very sloppily: "If the recruits see it and think that this small wood can be used as a pillar, it will not be a big joke to really attack the city in the future!" ”

With extreme contempt for the enemy, the Qing army guards left the city wall and went down to check the progress of the canal excavation, feeling that his strict and serious attitude was in stark contrast to the perfunctory Ming troops outside: "Look at me, even if you know that the other party will not really attack, you still have to dig a ditch seriously, really dig a pond out and store water...... That's how military training can work. ”

Although he did not agree with Deng Ming's plan, when Liu Tichun saw Deng Ming crawling out of the tunnel covered in dust, he still deeply felt that this sect disciple was really different, and this kind of thing going down the tunnel was generally disdainful of doing it himself.

Deng Ming made a new fuse, firmly connecting it with the fuse in the tunnel, still using incense candles as a delay fuse. After deploying this qiē, Deng Ming asked Liu Tichun and Yuan Zongdi to order the army to stay away from this area. If the black powder does not explode, it will at most have a scorching air current, but if there is an explosion, there will definitely be a shock wave, Deng Ming had experience it when he was in Kunming, and now he expects the shock wave of the explosion to destroy the city wall of Yunyang.

Because it has not been blasted, Deng Ming doesn't know how far away people are to be safe, so he just tries to let everyone go farther away. In the end, the Ming army retreated to a mile away from the blasting point.

The defenders of Yunyang noticed the abnormality of the Ming army, and felt that there were too many strange behaviors of the Ming army today, and they looked at them in a daze, but they didn't think it had anything to do with the city wall. Even if there was enough time, even if the Ming army had completed the preliminary preparations for the cave attack and planned to burn the pillars and let the city wall collapse, they should not hide the army so far away. Even if the walls collapse, they will not disappear without a trace, and being able to create a slope that can be climbed is a very successful cave attack.

Usually before launching a hole attack, the attacker will set up an offensive formation in front of the target wall segment, ready to seize the possible ramp at the first moment. The defenders will also be rewarded for this, and will also concentrate their troops to defend the dangerous city walls, while releasing water to irrigate the tunnels.

After seeing that all the people were away from the danger zone, Deng Ming lit the incense candles with his own hands, and then quickly left the tunnel, ran to the horse not far away with all his strength, jumped on the horse's back and walked away from the mound without looking back.

Yuan Zongdi and Liu Tichun waited to see the results of Deng Ming's hard work.

There were not many Ming troops around the two of them, and at this time, most of the Ming troops were building ladders and digging plum blossom piles in the distance, and the excavation of tunnels under several other new mounds was also continuing. Among this group of people, the most enthusiastic were the guards who had followed Deng Ming to Kunming, but a few of them, such as Li Xinghan, were worried that the amount of gunpowder was too small, after all, a coffin of gunpowder could not be compared with a warehouse of gunpowder in Kunming. When Zhao Tianba and Mu Tan heard about Deng Ming's plan, their reactions were similar to Liu Tichun's, they had never heard of this tactic, so they were both a little suspicious in their hearts.

Because he was worried that the ventilation in the tunnel was not good, the incense candle inserted in the gunpowder guide cable was very short, and Deng Ming estimated that the fuse should have been lit by now. Dry soil was added during the construction process, and the gunpowder bundles inside the walls were wrapped in cotton cloth, so there should be no problem with cháo.

"I don't know if a coffin of gunpowder is enough." Deng Ming shared the same concerns. He knew that soon the fuse would ignite the gunpowder in the coffin, and after a full reaction, hundreds of catties of gunpowder would turn into a mass of high-pressure gas with a very high temperature, estimated to be about 1,000 degrees. If the surrounding area can resist this pressure, this gas will eventually cool down slowly, and at the same time, it will keep escaping from the gaps, making Deng Mingbai have a hard time; And if one direction can't resist the pressure, the air mass will break through the ground and cause a violent explosion.

"If there's enough gunpowder, where does it come from?" Deng Ming pondered this question. It is certainly impossible to be at the center of the earth, and no matter how high the pressure of the air mass is, it cannot run underground; The other three sides of the horizontal level are solid earth, and the more fragile side is the tunnel direction, even if a brick-soil mixed wall is more than ten meters thick, its solidity cannot be compared with the earth.

But the most vulnerable should be the city walls, located above the blasting point. Deng Ming remembered that it seemed to be said in junior high school physics that pressure is equal to the product of area and pressure, and the area on the upper surface of the coffin is the largest.

"Luckily, I pushed the coffin straight in." Because digging tunnels is very hard work, when digging holes under the wall foundation, the Ming army naturally takes the size of the front section of the coffin as the standard, and the small section is small, and the workload is small. Deng Ming felt that because the section of the tunnel was small, the pressure on the more fragile tunnel direction should be relatively small.

However, Deng Ming thought of a lot of shortcomings, since the size of the confined space is inversely proportional to the pressure, then the space in the hole should be filled as much as possible, and the coffin should also be fully compacted with stones to compress the space to a minimum. If you can reduce the space by half, the pressure can be doubled, and the pressure will be doubled. In the future, it is necessary to use a special container for gunpowder, preferably a wooden box with a wide upper surface and a rather low one, so that the direction in which it is intended to be destroyed is subjected to as much pressure as possible.

With so many things to be improved, Deng Ming felt extremely frustrated that he hadn't thought of them sooner, and he was even less sure that he would be able to succeed today.

Zhao Tianba, who was standing beside Deng Ming, noticed that Deng Ming's face was happy and worried--happy because he remembered the pressure and pressure formula; I was worried because I immediately realized that my design had many shortcomings; Immediately afterwards, Zhao Tianba heard Deng Ming let out a long sigh, and when Deng Ming thought that he had not filled the blasting space with all his might, he suspected that this omission would greatly reduce the success rate of blasting.

"Mr. ......"

Zhao Tianba turned his head sideways to comfort Deng Ming, but as soon as he opened his mouth, he felt the ground under his feet suddenly shake, and then a deafening explosion came to his face, cutting off the words that he had not had time to spit out.

Zhao Tianba turned his head to look at Yunyang, and there was no city wall in sight, only smoke in the sky and a pillar of smoke and dust in the air.

Those who had been facing Yunyang City did not see what was going on, and some Ming soldiers, who had particularly good eyesight, felt as if they had seen the walls of Yunyang burst open from the inside out, and the masonry and ash inside rose into the air, as if a dragon was about to emerge from the belly of the city wall. At the same time as that loud noise, the dragon flew up from the surface of the ground into the air, and the smoke and dust brought up covered this section of the Yunyang city wall tightly, and nothing could be seen.

All the Ming soldiers raised their heads and looked at the column of smoke that kept going upward, and there seemed to be gunpowder in it that had not yet burned. After a while, a sudden rain of rubble fell near the blasting point, and a large amount of smashed bricks fell back to the ground from the air, spilling far away, and even falling on the heads of the Ming soldiers who were watching the movement from afar.

Liu Tichun, Yuan Zongdi, and Deng Ming were also hit by one or two small stones, and some gravel was rolling on the ground, and they still couldn't see the city wall behind them through the smoke and dust.

"The explosion exploded, but I don't know how effective the explosion is?" Deng Ming was anxious to see his results, but Yunyang City was filled with yellow smoke and dust, and he couldn't see anything.

At the time of the explosion, Yunyang's guards were drinking tea with the prefect in the yamen, exchanging contempt for the weak offensive of the Ming army. When the shock wave arrived at the yamen, the aftermath was already so weak that it couldn't even shake the water out of the two people's teacups. However, the loud noise still made the civil and military guards of Yunyang suspicious, and walked out of the yamen to see what strange things had happened.

By the time the two men arrived at the blasting site, the smoke and dust had dissipated so much that they could not see people from a few meters apart as they had when the explosion first occurred.

The guard leaned down and looked at the ground, which was littered with rubble, which looked like fragments of wall tiles, and the closer to the blasting point, the denser and larger the fragments became; Some of the Qing soldiers fell to the ground silently, others struggled for help, and the guards saw that the soldiers were bleeding from their noses and ears; The rubble and the soldiers' faces and bodies were covered with a thick layer of dust, and the guards reached out and touched it, and it felt like the sand used to build the walls.

At this moment, a strong wind blew, blowing away some of the already thin dust, and the guard raised his head and saw a huge gap in the city wall appear in front of him, the brick surface was gone, and the battlements near both sides of the gap were gone, and the soil inside was completely exposed. This gap is in the shape of a shè, and the www.biquge.info of the Biqu Pavilion is directly above the blasting point. Through this gap, the defender suddenly found that he could see the Ming army on the ground in the distance.