"Bo Yan, young man, what do you think of the Northern Expedition of the Lord Army?" In the front army's big tent, the rest of the people went to their own jobs, leaving only Lu Xun and Ma Jian left behind by Zhao Feng and talked on paper.

"General, I think the lord is going north this time in order to relieve the pressure on us and others in Hanzhong. I think that when General Zilong and they solve the matter of Xiliang, we can join forces in one place, and then march into Guanzhong to pacify Xiahou Yuan! After thinking about it, Ma Tan was full of confidence. Zhao Feng was noncommittal when he heard this, but looked at Lu Xun with an inquiring gaze.

"General, I think the lord's Northern Expedition this time is not easy!" Lu Xun's tone was more serious, but he still chose a softer tone. Looking at Ma Jian and Zhao Feng, Lu Xun slowly spoke: "Now that the lord's army of 300,000 is heading north, even if it has captured Tiger Prison Pass and Luoyang, the Guanzhong in the west is still in the hands of Xiahou Yuan, and the north of the Yellow River in the east is also the land of Cao Ying. If you wave your army northward again, you will inevitably be attacked on three sides; If the army is marching westward, there is a natural danger in Tongguan. In this way, I am afraid that we may not be able to achieve great results! ”

"I think so!" Zhao Feng also sighed. But after all, Zhao Feng also knew that Wang Shi went north to recover Luoyang, and the temptation was too great. Even a person as calm as Liu Bei couldn't help but take a chance. If he can enter the Guanzhong, he can naturally realize Zhuge Liang's Longzhong pair, which makes it difficult for Cao Ying to take care of both the beginning and the end. But now that he has been stumped, relying only on Liu Bei's strength, it is really not enough.

"Generals, don't worry, there are Mr. Xu Yuanzhi, Pang Shiyuan and Chen Gongtai to participate in military affairs, as well as the three generals and generals like Zhang Wenyuan and Wen Zhongye, I think even if you are invincible, you can be safe and sound." Ma Jian saw that the two of them were not too interested, so he diverted the topic and explained. Zhao Feng nodded slightly, then cheered up and said, "I'll deal with the enemy in front of me first, and then make plans!" "At the moment, scouts were sent to strengthen patrols, preparing to eat the opponent's raid team in one bite.

At the same time, Zhao Feng and Lu Xun were a little worried about Lao Liu, who had just led the army to capture Xingyang. It is said that it was captured, but in fact, it is a little inappropriate, because they almost took this ancient city of the Qin Dynasty without blood.

"The Xingyang city wall is dangerous, and it is an important place to defend the tiger prison, but there are only thousands of weak soldiers defending the city, why did Cao Ren abandon this strategic place so easily?" In Xingyang City, Zhang Liao frowned. It seems to be talking to himself, and it seems to be asking Pang Tong and others.

"I think Cao Ren wants to concentrate his forces and hold the Tiger Prison to block my army!" Chen Gong thought for a while. Although Xingyang is also a critical place, which is conducive to holding on, but under the attack on the southeast sides of Xuchang and Wancheng, Cao Ren may not be able to have enough confidence to defend Xingyang even if he is conceited. At this time, shrinking the forces and retreating to the Tiger Pass is the most realistic strategy.

"In that case, we will send the soldiers to the Tiger Prison to fight Cao Ren!" Liu Bei saw that Chen Gong and others said so, and the surname Suo made a decision to continue to march. At this time, the Malay newspaper said that Cao Ying of Hebei personally led the 200,000 troops of Liyang to Hanoi, and the goal was to rescue the Tiger Prison.

"Good! It seems that Cao Mengde can't hold his breath anymore! Liu Bei said with a smile. Pang Tong on the side thought for a moment and said: "Lord, Cao Ying came from Liyang to save the Tiger Pass, and he still has to cross the Yellow River." And we waited for us to march from Xingyang to Tiger Pass, and the journey was shorter. If we march with all our might, it is estimated that we can at least seven or eight days earlier than Cao Ying, and rush to the Tiger Prison Pass. Before that, if we can capture the Tiger Prison Pass in one fell swoop, we can force Cao Ying and us to fight a decisive battle in Henan, and at worst, we can also capture Henan and Hongnong. If it goes well, it may be possible to attack the west in one fell swoop! Therefore, he commanded and hurried forward to attack the Tiger Prison Pass! ”

As soon as these words came out, everyone was shocked. What Pang Tong said is theoretically completely valid. But even if he went to the Tiger Prison seven or eight days earlier than Cao Ying, would he be able to capture the Tiger Prison? Cao Ren has more than 40,000 troops in the Tiger Pass, and his people are good at defending the city, so it is really difficult to capture the Tiger Pass. After hearing this, Zhang Liao was the first to speak: "Liao Su knows that the military division Pang is resourceful, but he doesn't know what the military division's plan is now, but he can win the tiger prison pass in a few days?" ”

"Hehe, General Wenyuan, it's not a clever plan. It's just a siege weapon, which was created by General Zhao in the past, and it has been developed many times over the years before it was completed. Speaking of this, Pang Tong also sighed, and said with some regret: "If there was such a thing when it was said to be Xuchang in the past, I am afraid that Cao Ying would have already been awarded the head!" ”

"That's it!" Liu Bei knew that the organs made by Zhao Feng were definitely powerful enough, and the practice over the years had proved this more than once. Since Pang Tong was so confident, Liu Bei didn't say anything anymore, and immediately ordered the army to move at full speed, and the target was firmly closed.

Two days later, Liu Bei's front army and horses had arrived at the foot of the Tiger Prison Pass. Before Cao Ren, the general of the gate, learned of this news, he was already in a tight battle and ready to defend to the death, and at the same time sent someone to report to Cao Ying, who was leading the army as soon as possible. Cao Ren also knew that Cao Ying would arrive in as many as ten days, and as few as eight days. As long as you hold on for these few days, Cao Ying will handle the rest.

"Uncle Zixiao, don't worry, I have already checked it, rolling wood and stones, rolling oil arrows, and all kinds of city defense equipment have been put on their feet. I also led people to strengthen the city wall, if Liu Bei comes, he will be asked to lose his troops and generals! Above the city, Cao Hong's eldest son, Cao Fu, the captain of Fenwei who assisted Cao Ren in guarding the pass, talked eloquently. Cao Ren looked at the sturdy city wall, the abundant arrows and rolling wood and stones on the city, and the smoke of the oil pot, and nodded with satisfaction. With these, plus more than 40,000 officers and soldiers defending the city, he was confident enough to stop Liu Bei for more than a month. Seeing that it was getting late today, Cao Ren knew that it was unrealistic for Liu Bei to want to attack the city on a large scale today, but he still sent people to inspect overnight just in case, so he was relieved to go down.

In the early morning of the next day, the 90,000 people in front of Liu Bei's army, who had arrived at the Tiger Prison Pass, under the personal leadership of Liu Bei and Zhang Fei, all gathered at the Tiger Prison Pass to prepare for tackling the key problems. At this time, it is already the early winter, the Tiger Prison Pass is adjacent to the Yellow River, and the north wind on the river is blowing, which is very strong.

"This wall seems to be higher?" Liu Bei looked at the steep city wall and sighed softly. Beside him, Zhang Fei and Zhang Liao were silent, the former looked at the closed city gate, as if it would open in the next moment, and then rushed out of it like eighteen years ago.

"Lord, everything is ready to attack the city!" Just when Liu Bei and Zhang Fei were emotional, a sentence from Pang Tong, who stepped forward, interrupted their memories. Liu Bei nodded, looked at the dozens of trebuchets behind him, turned his horse's head to make way for the open space, so that the trebuchets could prepare to attack the city.

"Uncle, it seems that this Liu Bei is ready to smash stones again!" Looking at the dozens of trebuchets under the city, Cao Fu also smiled. There is a reason why he is so relaxed, not to mention the high danger of the tiger prison wall, and the terrain in front of the pass is also very narrow, Liu Bei can only arrange less than thirty trebuchets to smash at the same time. This density of stone rain is simply a symbolic blow to the soldiers defending the city.

Cao Ren hadn't noticed anything unusual yet, but Liu Bei quickly realized that something was wrong today. Because what Pang Tong ordered people to fill the trebuchet with was not stones, but jars. Liu Bei looked at it for a long time, and then asked, "Shiyuan, is this jar filled with fire oil?" ”

"No, my lord, this thing is gunpowder, not oil." Pang Tong replied with a smile.

"Gunpowder?" Liu Bei said in surprise when he heard this, he didn't know anything about this thing.

"Exactly, this is a sharp weapon developed by General Zhao in Xichuan to defeat the enemy. This time I marched into the Tiger Prison Pass, I knew that this pass was a rare Xiongguan in the world, so I asked Kong Ming and General Zhao for hundreds of such gunpowder jars in case of emergency! I took two experiments before, and I felt that this thing was really powerful, so I specially used it for tackling key problems. The lord can send an elite team, and after this gunpowder is powerful, he will immediately wave his army to suppress and cover the kill, and he will definitely be able to break through the level in one fell swoop! Pang Tong said with confidence.

"Okay, third brother, you can arrange this matter!" Liu Bei saw that Pang Tong was so confident, and he also nodded and agreed. At that moment, Zhang Fei arranged two teams of people, each with 5,000 elite soldiers, ready to take advantage of the chaos at any time. At the same time, the first batch of thirty jars has also been filled.

"Ignite, launch!" With Pang Tong's order, these thirty jars were lit with a lead drawn from the mouth of the jar, and then the entire jar was thrown into the sky, and in the expectant eyes of Liu Bei and Zhang Fei, they were directly smashed into the tiger prison.

"Bang! Bang! Bang! Then a loud bang rang out, and jars filled with gunpowder burst one by one on the top of the city. Most of them exploded after they reached the city, and some of them exploded in mid-air. But the loud bang, the shock wave caused by the explosion, and the flying pieces of broken porcelain after the jar burst, immediately caused a series of chaos.

"What's going on?" Cao Ren, who witnessed all this, was also surprised after seeing the power of the first round of gunpowder bullets. Nearly 100 soldiers were killed and injured at once. And even all those who survived were almost panicked by the bombing.

"Is this gunpowder?" Not only Cao Ren, but Liu Bei, who was barely a bystander, was also shocked when he saw such power. Beside him, Zhang Fei, who has always been not afraid of heaven and earth, and Zhang Liao, who is moody, are also devoid of demeanor. The former opened his mouth and let the saliva already flow; As for the latter, his always calm face also changed color in shock.

"Exactly, this thing was developed by General Zhao in Xichuan, and it is infinitely powerful. General Zhao once said that gunpowder will definitely change the future war! Pang Tong sighed. This is also the most proud work that Zhao Feng has made over the years, and it has cost him a lot of effort.

Zhao Feng knew the formula of black powder, which was fire, nitrate, sulfur and charcoal. Even the equations for the chemical reactions that occurred during the explosion were written verbatim. However, theory is theory, not to mention that this is only an extremely superficial theory, and there is still a big gap between practice and practice. In the process of researching gunpowder, Zhao Feng first encountered the problem of raw materials.

This fashion was in the Eastern Han Dynasty, charcoal and sulfur were available, but the fire and nitrate were still not served. Generally, saltpeter is just ground and mixed directly together as fire nitrate. Zhao Feng knew that the main components of fire nitrate were potassium nitrate and sodium nitrate, which were soluble in water, but now you can't put a whole stone in water to soak in it. Because of this, Zhao Feng's gunpowder plan was almost completely stranded.

Unexpectedly, since the capture of Hanzhong, by chance, Zhao Feng accidentally found a method of refining fire nitrate from Zhang Lu's alchemy notes. It is to mash the saltpeter and cook it with the radish slices. The boiled soup is filtered out of residues and concentrated to obtain relatively pure nitrate crystals. Together with the original charcoal and sulfur, these three elements of gunpowder were finally gathered.

As for what to do with this gunpowder, Zhao Feng also thought about it for a long time. At this time, the iron-smelting technology must not be able to make enough fine iron to make guns, and he was not proficient in this aspect. After a few failed attempts, I guess I'll have to make some bombs or mines or something like that.

This bomb converted from a wine jar, commonly known as jar thunder, is also the first gunpowder weapon developed by Zhao Feng that can be used on the battlefield. As for the specific structure of this thing, the older generation's commentary "Sui and Tang Dynasty" explains in detail, that is, the gunpowder mixed evenly according to the proportion is loaded into the wine jar, and then a bamboo pipe is inserted, and a fuse is inserted from the inside as a fuse, and then the mouth of the jar is sealed with clay. In this way, once the fuse is ignited, the entire internal gunpowder is ignited, and the gas and heat caused by the rapid combustion cannot be released in time, thus breaking the outer wall of the jar and causing an explosion.

It sounds very powerful, but in fact, the power is still relatively average. However, Zhao Feng estimated that such a big jar of thunder, once it exploded, it should hurt its muscles and bones. In order to increase the lethality, he also mixed pieces of broken iron in gunpowder. Once it explodes, even if it doesn't kill anyone, the flying iron is enough to break the heads of people nearby. This thing is powerful, it must be worse than those grenades in later generations, but Zhao Feng estimates that compared with those dirt roads and guerrilla mines, it is estimated that it is half a catty. Come to think of it, relying on these things, we have been working with little devils for so many years. No matter how ruthless Cao Ying is, he can't be as ruthless as a little devil.

Zhao Feng has been tinkering with his free time in Xichuan for so many years, and he has made nearly a thousand altar thunders, which only he and Zhuge Liang know. This time, Pang Tong accompanied the army to the Northern Expedition, and he had to face such a dangerous pass as the Tiger Prison Pass, so he used Zhuge Liang's relationship to get a batch of altar mines from Zhao Feng. Now it is used to deal with the Tiger Prison, and it is also a good place.

"But Master Pang, this gunpowder is only more than two hundred, and if you want to blow up the Tiger Prison in one fell swoop, I'm afraid it's a little difficult!" After watching it for a long time, Liu Bei also had a more accurate understanding of the power of the altar thunder, this thing is very fierce, but the real power is definitely not as bluffing as it seems. Liu Bei thought about it a little, and knew that it was a little unrealistic to rely on things to completely blow up the Tiger Prison.

"Tong also knows that this time is just to deter the enemy army with the power of this thunder, and there are new tricks below!" Pang Tong looked at Cao Jun who was at a loss on the city, and couldn't help but have a cruel smile on his face.

(To be continued)