"Build a city here?"
The idea is good, but what can we use to build it?
Besides, we don't have enough manpower, and the court is unlikely to provide us with enough materials.
"Just because we can't build it now doesn't mean we won't be able to in the future," said Li Yao. "Yesterday, I received a letter from the Prince of Yizhou. The cement workshop has already started production, and your fourth uncle and his team are working tirelessly. We will soon have a large supply. Once the cement arrives, it won't be difficult to build a city, right?"
"But what about before that?" Wang San'er asked. "I don't know why, but the barbarians are acting like they've gone mad this time. I suspect that even if the Great Snow seals the plains, they won't retreat. So, Mother, please help us come up with a solution."
"Is this your idea or Grand Marshal Xu's idea?"
"Well..." Wang San'er blushed and said, "Actually, I volunteered for it."
Li Yao smiled and shook her head, but she didn't blame Wang San'er.
So she went to the central military tent to find Grand Marshal Xu.
"Li Ru, do you have a solution to the barbarian attacks?"
"Yes."
"Please tell me!"
"It's actually quite simple," Li Yao said. "The reason we can't deal with the barbarians now is that we can't track their movements. We don't know where they are or when they will launch their attacks."
Elusiveness is the essence of guerrilla warfare.
"But even if we send out scouts, it's difficult to ascertain their whereabouts."
"Grand Marshal Xu, have you ever heard the saying 'to see far, stand high'?"
"Li Ru means that we should build a tall tower?"
Li Yao shook her head. "The tower is too short. We need to go higher."
Grand Marshal Xu: ...
The officers and soldiers: ...
If someone can reach the sky, they wouldn't be human but a deity.
Even Grand Marshal Xu, who has always trusted Li Yao, couldn't help but have some doubts this time.
Only Wang San'er continued to support her as always. "If Mother says we can reach the sky, then we definitely can!"
"But before that, I need a large quantity of sheepskin, cowhide, and enough strong and long ropes and cords."
"Alright, I'll arrange for it."
Obtaining sheepskin and cowhide on the grasslands is relatively simple. Grand Marshal Xu didn't request them from the court but instead sent a team with money to Yuhan Pass to purchase them from local herders.
A few days later, several large carts of sheepskin, cowhide, and ropes were brought back.
With the current technology, Li Yao couldn't build an airplane, so she could only make a hot air balloon.
While the balloon was being sewn, a structure over twenty meters high was erected to facilitate the inflation of the balloon.
When the enormous hot air balloon was completed, Li Yao brought out two sealed wooden barrels from her tent. They contained raw rubber, which could be used to temporarily seal the gaps between the sheepskin.
Then dozens of people hung the massive hot air balloon on the structure and attached ropes above with a basket below.
Looking at this enormous and peculiar contraption, people couldn't help but wonder, can this thing really fly to the sky?
"I thought it would be a pair of giant wings, but it turned out to be a giant ball."
"I thought it was going to be a paper kite, no, a leather paper kite."
"Li Ru," Grand Marshal Xu watched with confusion, "how is this thing supposed to fly?"
"It still needs one more thing."
Li Yao moved a small gasifier out of the tent. It was crafted by Xia Xian and used coal as fuel. There was also a hand-operated blower installed below.
After adding coal to the gasifier and igniting it, Wang San'er began vigorously shaking the blower. A large amount of air blew into the coal, causing it to burn vigorously, and the resulting hot air quickly entered the hot air balloon.
After two quarters of an hour, the originally deflated hot air balloon swelled up in front of everyone's eyes and began to float upward, pulling the connecting ropes straight towards the ground.
"It's almost ready to fly," Li Yao said. "Grand Marshal Xu, would you like to give it a try first?"
To be honest, Grand Marshal Xu felt a bit apprehensive.
This contraption did look like it could actually fly, but what if it flew too high and couldn't come down, or if it suddenly broke at a high altitude...
"Cough, cough, I'll stay down here and oversee the situation."
"Then I'll go by myself."
Li Yao boarded the hot air balloon. However, it was her first time riding in such a rudimentary one. Nevertheless, she believed that there wouldn't be any problems. Even if the hot air balloon leaked air, it wouldn't descend directly but rather slowly.
With enough coal loaded in the basket, Li Yao and Wang San'er were ready to ascend.
"Liu Hu, you must pay attention to the ropes," Wang San'er reminded. "Otherwise, we might be blown far away by the wind."
"Understood!"
Liu Hu and Zhang Shun, along with a dozen other people, slowly released the ropes below. As the heat increased, the hot air balloon swiftly ascended into the sky.
But in the blink of an eye, it reached an altitude of several dozen meters.
"Wow, isn't this high enough?" Wang San'er couldn't help but ask, looking at the height above the ground.
"It's still early," Li Yao replied. "If we really want to fly, we can go dozens of times higher than this."
"How high?"
The typical altitude for manned hot air balloons is around one kilometer, and Li Yao had prepared ropes of that length. However, in reality, they couldn't fly that high because the winds in the sky were too strong. The hot air balloon ascended at an angle, which increased the danger, so a few hundred meters would be sufficient.
When the balloon reached a considerable height, the pressure on the ropes increased. At this height, even the bold Wang San'er hesitated to look down.
Li Yao looked into the distance. The weather today was clear, with high visibility extending for more than ten li (a Chinese unit of distance). She then waved a small flag a few times.
This was the agreement she made with Grand Marshal Xu. When he saw the waving flag, he would send out a small cavalry unit, heading towards Yuhan Pass. She wanted to test how far she could see from the hot air balloon.
The cavalry unit quickly ran quite far. When their figures became gradually indistinct and difficult to see, Wang San'er estimated, "Probably less than thirty li. That distance should be enough!"
"Not enough."
Thirty li was at most a small advantage on the battlefield, far from the level of overwhelming dominance.
Li Yao took out a long cylinder from her small backpack. She had selected a few pieces of glass with the highest transparency from the glassware Xia Xian crafted and made several simple telescopes.
After slightly adjusting the focus, the cavalry unit appeared in the telescope.
After conducting final tests, it was found that by combining a hot air balloon with a telescope, one could see a cavalry squad at a distance of fifty li, which is approximately twenty-five kilometers.
However, compared to the theoretical distance of one hundred kilometers, it falls short by a large margin.
The key issue lies in the lack of transparency in the telescope lens, causing blurriness at greater distances.
Nevertheless, at a normal pace, it would take the cavalry about an hour to cover the fifty li.
By knowing the enemy's movements one hour in advance, even being able to monitor their every action and respond accordingly, the Daling Army would be virtually invincible, as long as the difference in strength isn't too vast.