Jiang Jin smiled. "Given the coldness of Gefeng's winters, the permafrost layer generally doesn't exceed six feet. The tunnels we plan to dig will be over ten feet deep, or even deeper, so it won't be affected at all."
If the tunnels were situated five to seven meters underground, the year-round temperature could be maintained at around twenty-two degrees Celsius—a perfect guarantee of being warm in winter and cool in summer.
Even if they didn't dig that deep, the temperature wouldn't drop too low. Digging during the winter was entirely feasible.
Moreover, the tunnels didn't need to be exceptionally long. They just needed to select one or several hidden locations near Gefeng to serve as tunnel entrances.
The current brick kilns and mining areas weren't connected by official roads, but rather by the mountain trails Jiang Jin had her people carve out. The entrances and exits could easily be placed anywhere near these trails.
This had an added benefit: even if someone discovered the brick kiln, they wouldn't easily find the tunnels.
Of course, they had to design multiple gates within the tunnels, so that if they were discovered, the passageways could be quickly sealed off.
She also planned to set up troop-hiding chambers, 'maze caves,' and double-layered walls among other military installations. If necessary, they could lure enemies into the tunnels and eliminate them.
She was quite familiar with tunnel warfare.
However, digging such tunnels would not be easy; the ventilation shafts and observation holes required careful planning and design.
The others didn't know what a "permafrost layer" was, but they understood the gist of her words and lowered their heads in deep thought.
The winters here were long, lasting for several months. If this could truly be implemented, there would be a massive amount of manpower available, making the completion of this project entirely possible.
Jiang Jin continued, "Rest assured, I already have specific plans."
She briefly outlined the routes and the internal structures designed for both offense and defense. Hearing this, everyone's eyes lit up, wishing they could put the plan into action immediately.
Early the next morning, Jiang Jin brought Yun Chengxuan to the cultivated land next to the horse farm.
Due to time constraints, they hadn't reclaimed much wasteland—only about five acres. Spinach was planted on just a fraction of the land, while the rest was dedicated to white radishes and napa cabbages, as these two had higher yields.
Over the course of twenty-odd days, the vegetables had grown exceptionally well.
Mu Qing seemed like a completely different person, his face flushed with excitement. "My Lord, based on their current growth, the yield of these vegetables will certainly not be poor."
Smelling the rather pungent odor, Jiang Jin couldn't help but say, "You must also pay attention to the amount of fertilizer you use. More isn't always better."
There were many commoners in the city, and with only five acres planted so far, they didn't need to worry about a shortage of compost; they had more than enough.
Mu Wanbai covered her mouth and chuckled from the side. "Rest assured, My Lord. My grandfather cherishes these vegetables dearly; he knows what he's doing."
Jiang Jin knew this well. Mu Qing practically wanted to sleep in the vegetable patches. He took daily notes, observing and recording their growth.
In the afternoon, Jiang Jin rode her horse to the brick kiln. High walls had already been erected here. Inside, aside from the workers' living quarters, large factory buildings had been constructed.
To ensure that brick firing could continue normally through the winter, in addition to heated walls, Jiang Jin had specially designed an underfloor heating system.
When the time came, they would only need to feed charcoal into the furnace chamber through the operating port. The heat generated by the charcoal fire would conduct through the flues to the floor tiles, which would then radiate the heat upward.
As long as she had a large amount of raw materials excavated in advance and stored in the factory, they could continuously fire bricks throughout the entire winter.
She had no other choice. Building the city walls required an astronomical number of bricks, so she had to strive to produce as many as possible during the winter months.
Once the weather warmed up next year, construction on the city walls could begin immediately.
Speaking of which, it was time to put cement production on the agenda. The raw materials were basically all gathered; the only remaining issue was the technology.
Achieving a high-temperature calcination of 1500 degrees wasn't a big problem, but the crushing and grinding processes were tricky. Relying on manual labor would be too inefficient.
She planned to build a water-powered crushing and pounding machine, as well as a grinder. There were too many things to do; she had to take it one step at a time.
Xia Zhong and Duan Zhuo walked over, covered in dust. Although they were the managers here, they would pitch in and help with the physical labor whenever they had free time.
Jiang Jin instructed them, "We still need to pick up the pace, mainly because the weather is starting to turn cold. There isn't much time left. We need to dig up and stockpile more raw materials like clay."
The two hurriedly complied. "Rest assured, My Lord, we understand."
Jiang Jin nodded. "Go back to your work. I'll take a look around on my own."
She took a tour around the kiln, and as she was about to leave, she called over Lu Ping, the commander of the garrison stationed there. "Have you seen any suspicious individuals nearby recently?"
Lu Ping shook his head. "No. This place is remote; hardly anyone ever comes this way."
"Expand your reconnaissance perimeter just in case of emergencies. If enemies do come, have the workers evacuate into the cellars, and lure the enemies into the dense woods for jungle warfare."
Although Jiang Jin had occupied Gefeng City, that was the extent of it—she had no control over the entirety of Gefeng County.
This also meant that her people lacked guaranteed safety outside the city. Therefore, she had ordered a cellar to be dug in a hidden location in the mountains, where people could hide if necessary.
Lu Ping nodded. "Rest assured, My Lord."
Just as Jiang Jin returned to the county magistrate's office, Dong Si ran over to report, his face brimming with excitement. "My Lord, My Lord, we found the black coal!"
Jiang Jin was delighted. "In which direction?"
His expression turned solemn. "To the northwest, in Qinghuai County. It's quite a distance away."
Jiang Jin frowned, recalling the geography of Liuxiang Commandery. "It hasn't been mined by anyone yet, right? How far is it?"
Dong Si nodded. "No one has mined it. That place is a stretch of barren mountains. It's over ten miles from the nearest village, and probably forty to fifty miles from us."
That was indeed quite far. The main issue was that her current military strength was insufficient; stretching her lines too long would make it difficult to manage everything.
"I'll go take a look tomorrow." Jiang Jin decided to assess the situation first.
If they could mine it, they would; if not, they could wait until later. After all, for the time being, coal was not an absolute necessity for her.
Of course, having it would be ideal. The heat produced by coal was incomparable to that of charcoal, and it would be much more effective for iron smelting, forging, and manufacturing cement.
The next day, Jiang Jin led her people out of the city.
Inside the city, things had become bustling due to the military recruitment.
Today, Xie Nanxiao and Xia Chanyi were in charge of the recruitment.
Neither of them expected so many people to show up to enlist, especially on the female soldiers' side, where a long queue had formed.
Xia Chanyi already had some experience with recruitment. She was in charge of the female soldiers, leading her subordinates in registering identity information, conducting physical examinations, and so on.
"Name and age," the registrar asked.
"Mu Chichi, 16 years old," the young woman's voice rang out loudly.
Xia Chanyi found the woman somewhat familiar. It took her a moment to remember that this was the very same woman who had shouted, 'I will not die on my knees!' that day.
Xia Chanyi wasn't surprised that she had come to enlist. She asked with concern, "Have your injuries healed?"
Mu Chichi's face was still a bit pale, but her expression radiated determination and passion. "Thank you for your concern. I am fully recovered."
As if worried that Xia Chanyi might reject her, she quickly added, "I have a strong constitution."
Saying this, she couldn't help but puff out her chest and stand taller, silently demonstrating that she was perfectly fit.
Only after entering the city did she learn that Gefeng actually had female soldiers!
Women being allowed to serve in the military was something she had never even dared to dream of before. What was there to hesitate about? She immediately came to sign up.
She hated the Quzhao people and all the barbarian tribes. Her family members and many of her fellow villagers had been slaughtered by them.
Now, she was all alone in the world with absolutely nothing to her name. What did she have left to fear? At most, it was just her own life on the line.
