With a cannon foundry, the cannon naturally does not have to worry.

With a shipyard, naturally there is no need to think about shipbuilding.

For Zhu Mingzhong, who is in Qinghe, the problems he needs to consider are nothing more than the training of new soldiers, the manufacture of weapons, and of course, the construction of the earthen ramparts in the north of the city. It was the so-called "Annan Army" that marched less than 30 miles a day on average, and it was not in his consideration at all.

Compared with the Qing army, for Zhu Mingzhong, the city wall is more important.

Qinghe County has no city walls!

Qingjiangpu has never had a real city wall, and no magistrate has proposed to build a city. Although the Qinghe River is the confluence of water and land, the north and south are to rush, it is the Huaihai Road, the Huaiguan Road and the Caoyun Governor's Palace, although it is said that the market is prosperous, but it is the prosperity of the market that has created dozens of miles of cities and towns along the river, but it restricts the expansion of the county seat.

When Qinghe repaired the county seat during the Hongwu period, the county seat of Qinghe, with a population of thousands, was only 200 zhang wide. Later, with the northward migration of Yongle, the Qinghe River became the key point between the north and the south, and the market that flourished by the river completely surrounded the small city wall, coupled with various reasons, although this Qinghe County was prosperous, it was almost equal to no city wall, and even the old city wall was in disrepair for a long time, and almost collapsed.

In the past, there may not have been a need to build a city, but now, in the face of tens of thousands of Qing troops heading south, and Qinghe County itself is located north of the Yellow River, building a city has become the first priority.

It's just that what kind of city wall should be built has caused a debate in the Jingluo Embassy from the beginning, after all, this Qinghe market is dozens of miles, and such a big city is not something that can be repaired if you want to. In the end, it was Zhu Mingzhong who made the decision to build an earthen polder north of the canal as a fortification.

"Qinghe County is located in the hinterland of the impact plain in northern Jiangsu, a horse and a flat river, there is no mountain stone to be mined around, and it is far away to take stones hundreds of miles away and the water is far away to quench the thirst."

This is the reason why Zhu Mingzhong decided to build the earthen polder, after all, the war situation is urgent, the earthen polder may not be as good as the city wall, but it can still play a defensive role, and the sooner the time is required, the better.

Early in the morning, Zhu Mingzhong came to the construction site outside the city under the escort of his own soldiers, as soon as he left the city, he could see a soil polder as high as more than 3 feet high, on the earthen polder, there were people recruited from the Huaiyang countryside everywhere, maybe the people of the people were not willing to be soldiers, but it did not mean that they would exclude the idle time in the farm, earn a "foreign block", after all, idle at home is also idle, and thanks to these tens of thousands of people, it is only so that the earthen polder that is as long as thirteen miles can be built nearly three feet high in just half a month.

"Pingyu Gate" is the northernmost "city gate" of Tuwei, and it is also one of the most important "city gates". After coming to the "Pingyu Gate", Zhu Mingzhong saw that his senior brother was discussing something at the city gate with several young scholars, most of whom were scholars from Qingjiang Academy. Qingjiang Academy, which was built in Jiajing 20 years, is known as "the first academy in Hebei". The gate of the study house is northward, facing the canal, and the director of the Ministry of Engineering of the Qingjiang Cao Shipyard has been added and repaired many times, and has successively built the Ancestral Master Palace, Daguan Building, Wenchang Building, "Swen Zaiz" Fang, etc., and renamed "Qingjiang Academy", there are nearly 1,000 bachelors in the academy all year round, even at this time, there are hundreds of students studying in the academy, and now Zhu Mingzhong's master Zhu Zhiyu is teaching in the academy. And the scholars in this academy naturally became a talent pool for Zhu Mingzhong's governance of Huaiyang. And now, Zhu Daxian, who supervised the construction of the city wall, naturally recruited some scholars from the academy as assistants to assist him in building the city.

After boarding the "Pingyu Gate", Zhu Mingzhong did not bother Zhu Daxian, but stood directly on the city gate, looking at the people who were constantly tamping the earth wall, and the voices of the people who were covered in dust made a neat trumpet, and the stone rammer operated by five or six people was constantly raised with the trumpet, and the loose soil was tamped down.

Different from the ordinary city wall, this earthen polder does not use the process of building rammed earth with slabs, but uses the damming method that the people on the banks of the Yellow River are best at, and uses the method of building a river dam to build an earthen polder to defend the city. It's just that unlike ordinary river embankments, this earth polder has a large edge and corner every fifty zhang, and only that area adopts the process of rammed earth built by slabs.

And this is Zhu Mingzhong's "city wall" designed by borrowing from the European fortress, which is more similar to the Dutch-style fortress, using an earthen wall as a defense with a thickness of more than ten meters, but because he is not a civil engineer, and the understanding of the fortress is only through network information and pictures, so the current "fortress" in Qinghe County is just borrowing some concepts of "fortress", such as reducing the height of the city wall to reduce the impact surface, trapezoidal thick polder wall, This kind of embankment-like wall can make full use of the topography and soil volume to absorb the kinetic energy of cannonballs, and the low position of the wall greatly improves the defense ability of the corresponding cannons.

Of course, there are also the large bastions on the "river embankment", which makes it possible to expose the attacker to more than one bastion surface at any point of the castle, and the defenders can use crossfire to perform multiple strikes.

“…… The excavated raw soil should be all piled up in front of the moat to form a gentle slope of ten feet......"

Although Zhu Daxian was not an engineer, like many scholars of this era, as the supervisor of the construction site, he was undoubtedly competent, and even in the shortest time, he had already understood the characteristics of this city wall, that is, it could prevent shelling.

"Student understood!"

Zhu Daxian's side looked at the earthen wall specially piled up outside the moat, and after thinking for a while, he nodded and said.

"Only in this way can it resist the shelling of the earthen wall by the Qingyu Hongyi cannons, and the cannons fired by them can be sucked by the soil slope without causing damage to the main wall, while the artillery on the main city can shell the Qingyu ...... at will."

Listening to the young man's explanation, Zhu Mingzhong smiled slightly, this is exactly the role of the "impact slope" in front of the trench in the fortress, looking at the young scholars who followed Zhu Daxian, maybe there are various evaluations for the scholars of this era and the people of later generations, but it is certain that they are the smartest group of people in this era, and what is needed now is to guide them and let them develop in the direction of "learning to apply", rather than indulging in the eight-strand article.

Perhaps, the heavy responsibility of changing the times ultimately lies on them.

"The intention of the strategy is this, the reason why the Qing captives entered the customs was invincible, all because of their fierce artillery fire, so it ......"

Suddenly, Zhu Daxian, who was talking to the students, saw Zhu Mingzhong beside him, his eyes widened, and then he asked in surprise.

"Jingluo, why are you here?"