There is a wall on Diaoyu Castle Hill that extends to the river, and this wall, called the word wall, can not only restrict the movement of enemies under the city, but also protect the dock of the navy. Wang Li took Ouyang Xuan and Huang Dagen and walked along the wall to the side of the mountain. To enter the castle on top of the mountain, you need to pass through a long, winding mountain road. The trail was a path carved out of the cliff, narrow enough for one person to pass through, and completely exposed to the fire of the defenders above the trail. There are corner forts and stone hills at the dangerous points and corners of the trail, and it is not a lie that "one man is a pass, and ten thousand people are not open".

After a corner fort halfway up the mountain, the road in front was suddenly interrupted, and there was a cliff more than 100 meters deep below, but the road reappeared in front of the corner fort dozens of meters in front of it. Just when Ouyang Xuan was wondering how to overcome this natural danger, he saw Wang Li clapping his hands rhythmically at the opposite side. A group of soldiers immediately appeared in the corner fort opposite, holding logs about a meter long with the thickness of a bowl. One by one, the logs were stuffed into the holes in the edge of the cliff, and the thick planks were laid on top of them, and in a short time they became a wooden plank road. Wang Li led the two to continue walking, explaining as they walked. It turned out that this section of the cliff was deliberately not dug when Diaoyu City was built, but a hole was dug in the cliff wall, and a temporary plank road was laid when needed, and it was withdrawn immediately after the passage was passed. The advantage of this design is that even if the Mongols tried their best to attack halfway, they had to retreat in the face of this insurmountable natural danger. The more Ouyang Xuan walked into the city, the more he was amazed, the defensive design of this Diaoyu City was too exquisite, and Hengyuan Fort was really far inferior to it.

When they arrived at the official office in the hilltop city, Wang Li introduced Ouyang Xuan and the others to Zhang Jue, and reported the Annihilation of the Mongol fleet by the Thunderbolt Army. Zhang Jue didn't care when he first heard that Ouyang Xuan was the commander of Yongkang County, but when he heard that the Thunderbolt army had annihilated more than 30 warships of the Mongolian army without any damage with less than ten ships, he couldn't help but be surprised. At that moment, Ouyang Xuan gave a brief introduction to the past battles between the Thunderbolt Army and the Mongols, but Zhang Jue regained his disapprehensive look, after all, the battle record from Ouyang Xuan's mouth was too shocking, and it was too similar to the results reported by Yu Xing to the imperial court. What's more, he hadn't heard of the name of the Thunderbolt Army before, he just said that Ouyang Xuan was bragging. In Zhang Jue's view, although this young county magistrate who is a few years younger than himself has extraordinary words and deeds, and has a firm determination to resist Mongolia, he is a little frivolous after all. Therefore, when Ouyang Xuan said that this trip was specially for Diaoyu City to send a sharp weapon to defend the city, Zhang Jue just laughed, only saying that he was exaggerating again.

Ouyang Xuan saw that Zhang Jue was undeniable, knowing that he was not what he said, and he was speechless for a while. At this moment, his hand inadvertently touched the musket at his waist. Before entering the city with Wang Li, he and Huang Dagen had handed over the short knife they had brought with him, and even took off their armor, but they forgot to take off the musket for a while. Wang Li and the Diaoyu City soldiers did not recognize the musket, so the two inadvertently brought the musket into the city. The musket was still in the hands of the Thunderbolts' elite scouts, short but powerful. Since the parts of the gun and the brass bullets used are handmade, the cost is very high, and the production quantity is not large. On this trip, Li Shuang ordered the arsenal to equip him and Huang Dagen with one and fifty rounds of ammunition each. When he was in Xuzhou, Ouyang Xuan used this gun to shoot a water bandit who rushed into the cabin directly in the head.

Seeing Zhang Jue's disapproval, Ouyang Xuan decided to show him his real kung fu. At that moment, he pulled out his pistol and said to Zhang Jue: "Lord Zhang, the artillery is far more powerful than this musket, please allow me to try it first." After saying that, he turned around and walked to the courtyard of the official office. Zhang Jue and the others didn't know what Ouyang Xuan wanted, so they had to follow him to the courtyard. It was the beginning of November, and it was already cold, and a large flock of crows were making noise on the top of a large tree in the courtyard. Ouyang Xuan loaded the bullet and raised the gun to shoot, and after a loud bang, a crow fell to the ground with the leaves. To say that this can shoot down crows without aiming can only be said to be too lucky, or that there are too many crows in this tree.

This shot surprised Zhang Jue and Wang Li, but not because of the crow that was shot - there were not a few people in the Song army who were good at using crossbows, and the two were the best among them, but because of the loud sound of muskets. Seeing that the two were interested, Ouyang Xuan asked Wang Li to fetch a discarded iron helmet. After the gunshot, the iron helmet was pierced without any suspense. You must know that ordinary knives and arrows cannot penetrate iron helmets at all, only large bed crossbows can. Looking at the light smoke of the musket in Ouyang Xuan's hand, Zhang Wang and the others were dumbfounded, this little thing can have such power, if that cannon is a hundred times more powerful, wouldn't it shake the mountains? There was an urgent idea of insight. It's just that it's dusk, so I have to decide to try again tomorrow. Before going to the inn to rest, Ouyang Xuan gave Zhang Jue the musket and the remaining more than 40 copper bullets, and Huang Dagen also gave his musket ammunition to Wang Li when he saw this, and the two were naturally overjoyed.

In the early morning of the second day, when Ouyang Xuan followed Zhang Jue to the city wall near the naval wharf, Huang Dagen and Wang Li had already waited for a long time. At this time, a large open space had been cleared under the city wall, and the two fortress cannons brought by the Thunderbolt army had set up their gun positions, and they could be fired at the first order. In order to prevent accidental injuries and leakage of secrets, there are no more idle people around.

Seeing that Ouyang Xuan and Zhang Jue had already stood still, Huang Dagen waved the flag, and the two cannons opened fire one after another, targeting the woods and rocks three miles ahead. The first door was filled with shotguns, and after the cannon sounded, a large number of trees in the front row blew like a strong wind, and their heads were shaved by the brush; The second cannon fired solid shells, destroying all the trees in its path and shattering a large chunk of rock. The earth-shattering noise and power of these two cannons not only shocked the defenders of Diaoyu City who participated in the test cannons, but also made Zhang Jue and Wang Li completely believe Ouyang Xuan's words. This test gun test was also the beginning of the story of the trio later fighting Mongolia together.

In the following days, the Thunderbolts instructed the Diaoyu defenders in the placement and drills of artillery. These two fortress cannons were selected by Ouyang Xuan from the newly made cannons, the surface of the cannon body was smooth, and the inner wall of the cannon barrel was also carefully polished. There are two types of barrel manufacturing technology: mold casting and boring and milling. At present, due to the power and machine tools, the Thunderbolt Army adopts the mold casting method with simple process and low cost. The quality of the barrel made by this method is poor, mainly because the molten iron pouring mold will produce bubbles to form sand holes of different sizes, and even potholes in the barrel. However, the two cannons sent to Diaoyu City only had very few sand holes, and the quality had reached the ceiling of the cannon casting method.

Although these two cannons have been lightweighted and have been made the lightest under the condition of ensuring their power, they still have more than 1,000 catties each. It took dozens of brawny men a whole day to install them on a gun emplacement east of Diaoyu City, overlooking the only way from Diaoyu Mountain to land. After the artillery was placed, Huang Dagen led people to teach the daily maintenance and combat methods of the artillery, and also preset the shooting elements of the operation. Artillery is a technical unit, in addition to the need to be familiar with the performance of artillery, but also need a certain understanding of gunpowder shells, ballistic firing range, target detection, wind deviation and other factors in order to give full play to the maximum effectiveness of artillery, which cannot be completed in a short period of time. Therefore, Huang Dagen tested and copied the shooting Zhuyuan, and the Diaoyu City artillery only needed to be selected according to the situation on the spot during the war.