Chapter 1413 Civil Engineering Dog’s Glorious Moment

When Tian Yu, the captain of the Wuhuan Guard, was still in Youzhou in his early years, he was at odds with Wang Xiong, the governor of Youzhou.

Tian Yu advocated being tough on the Hu people, while Wang Xiong advocated being gentle on the Hu people.

In the end, Cao Rui chose Wang Xiong not only because of their identities and backgrounds:

Tian Yu was just a surrendered general, and he was of humble origins and had once followed Liu Bei.

But Wang Xiong was different. He was promoted by Cao Pi himself and was from a Shandong family.

More importantly, Cao Rui's choice of Wang Xiong could not only reduce the pressure on the border of Youzhou, but also draw more manpower and material resources to the west to resist Ji Han.

Even with the easing of relations with the Hu people, war horses could be obtained through trade with the grassland.

But everything has its advantages, and there must be disadvantages.

The years of peace on the border of Youzhou, coupled with the frequent exchanges with the Hu people, not only led to the slackness of Youzhou's military, but even the frontier guards such as the sentry camps were gradually abandoned.

"Baoqiu River is actually a pack road connecting Youzhou and the outside of the Great Wall. Youzhou's caravans often take this road to transport salt and iron to the market outside the Great Wall."

"After Tian Yu left Youzhou, there were also tribes outside the Great Wall who drove their livestock along this road to Youzhou to sell."

"But the market is mostly in autumn. Now it is summer and the river is high, so few people pass by."

The old witch pointed to Baoqiu River and explained to General Zhendong:

"My lord, don't think that you can only ride side by side by the water now. When the water is less in autumn and the bottom of the water is exposed, this place can even accommodate a large group of cavalry."

"When I was young, Wuhuan was still strong, and they often took this road to the south to plunder the Han area."

At this point, he looked at the general carefully.

General Zhendong had a calm face, his eyes fell on the road beside the Baoqiu River where only two people can ride side by side, and he said slowly:

"It is enough to ride side by side, but the premise is that we cannot be discovered."

Old Zhu Wu hurriedly said:

"Now the livestock on the grassland are fattening and growing fat, and no tribe will come at this time."

After hearing what Old Zhu Wu said, General Zhendong did not speak, but his eyes were looking to the south.

"When do the caravans from Youzhou usually go out of the border?"

"My Lord, the Han caravans go out of the border, mostly to trade livestock furs and the like with the tribes on the grassland, basically in autumn."

Then there is no problem.

Let someone call Pei Xiu up and tell him:

"From now on, you must not only write down the sections of the road we have passed, but also draw the mountain shapes and terrain. Do you understand?"

Pei Xiu nodded:

"Xiu understands."

As a disciple of Feng Guiwang, you may not know other things, but you must know mathematics and cartography.

It is said that this is the first knowledge that Feng taught since he came out of the mountain. It is the first knowledge.

Pei Xiu himself is extremely talented, and he has a strong interest in map drawing. He is like a fish in water when he becomes a disciple of Feng Guiwang.

He has participated in the map drawing of the Han army in recent years.

After a few more years of experience, he will enter the court and officially participate in the mapping of the Han Dynasty.

Maps belong to the court secrets. The more precise the map, the higher the level of secrecy.

Not to mention military maps. If ordinary people dare to keep them privately, they will at least start to plot treason.

Now Pei Xiu does not need to worry about his future at all.

The only question is how far he can go.

Being able to follow General Zhendong to go on an expedition and make meritorious deeds will undoubtedly write a strong stroke on his resume.

——

Although the water volume of the Baoqiu River surged in summer and the road along the waterside could only accommodate two horses riding side by side, it was a smooth road for the Han soldiers who had just passed the swamp and the poisonous valley.

If they did not need to worry about being discovered, they would not even need to send out scouts, and just follow the Baoqiu River all the way south.

Seven days later, General Zhendong led 7,000 elite soldiers to a large bay quietly. This was not only the closest to the ancient Yuyang Pass, but also the last large bay for the army to hide.

Less than 20 miles to the south was the Yuyang Ancient Pass.

As long as the army appeared at the mouth of the bay, it would be immediately discovered by the guards of the Yuyang Ancient Pass.

The Yuyang Ancient Pass was built on the west bank of the Baoqiu River. The terrain in front of the pass was narrow and could accommodate at most a thousand people to attack the city.

The east bank of the Baoqiu River cut through the mountains and was impassable.

There was a mountain on each side of the pass.

If the Guancheng is an iron lock, then the two mountains in the east and west are two iron gates.

The three together constitute the incomparably solid key to Youzhou.

As long as there are three to five thousand defenders in the Guancheng, and one or two thousand troops stationed in the east and west mountains, even an army of tens of thousands will find it difficult to advance.

Of course, the Guancheng is not without weaknesses.

That is, when the water level of Baoqiu drops in autumn, exposing enough riverbed, if the Guancheng defenders fail to block the riverbed in time, they can use the advantage of cavalry and pass quickly on the riverbed at the cost of heavy casualties.

Then turn around and attack from front and back. As long as Youzhou fails to rescue in time, it is enough to capture the pass.

But this weakness is equivalent to nothing for General Zhendong.

Because she can't wait until that time.

And she can't afford such casualties.

Putting down the telescope, General Zhendong looked at Pei Xiu, who also held a telescope in his hand, and asked:

"How is it?

Pei Xiu estimated in his mind and shook his head, "It's hard to say, I need to go back and measure it. "

Gestured for a moment, and then said, "Even if it works, the enemy army may be able to move to the mountain in the west to hide..."

"Don't worry about the mountain, just take care of the pass."

General Zhendong stared at Pei Xiu and said slowly:

"I urgently summon you to come here with the army just to solve the problem, not to ask you to ask questions."

"No matter what method you use, you must do this for me, otherwise you should know the consequences."

I don’t know if the weather was too hot or the pressure from General Zhendong was too great, Pei Xiu subconsciously let out a sweat:

"Students understand."

Then he raised the Qianli Mile Mile again and observed it carefully.

General Zhendong did not disturb him, but just looked at the mountain on the other side of Guancheng.

If you want to pass this pass successfully, in addition to winning the pass, you also need to take down the mountain on the west bank that depends on the pass.

As for the mountain on the east coast, it is not that important.

There is a Baoqiu Water separated by a river. If Guancheng is gone and the mountain on the west bank echoes, the military value of the mountain on the east bank will be greatly reduced.

There is a threat, but not a big threat.

After Pei Xiu finished observing, several people quietly retreated down the mountain. The general of Zhendong along the way did not disturb Pei Xiu's thinking. Until he returned to the water bay where the army was stationed, he asked:

"What are your thoughts?"

Pei Xiu pondered for a moment and replied:

"It's not impossible. The outer city of the gate is about one meter away from the water surface. As long as the water level of the Baoqiu water can be raised by one meter, it can indeed reach the city wall."

His eyes fell to the rushing Baoqiu Shui in front of him, and said thoughtfully:

"I have calculated the amount of water in Baoqiu water these days. If you want to raise the water level by one meter, you only need to store water for two days, and it will not exceed three days at most."

"But there is a problem, that is, find a water storage area of ​​at least one mile in radius. Of course, this is the minimum requirement, preferably one and a half miles or even two miles."

General Zhendong pointed to the water bay where the army was located and asked:

"How is it here? It looks big enough."

Pei Xiu shook her head:

“Big is big enough, but the location is not right.”

He pointed to the bend of the downstream water flow, "The exit is too big, it is difficult to build a dam, and the temporary dam is not solid. If it takes too long, there is a risk of collapse."

"If you build a dam there, the foot of the mountain will not be high enough, and you need to increase it."

While saying that, he shook his head, "The project volume is too large, we don't have enough manpower. If we really want to start construction here, it is very easy to be discovered by thieves. It's inappropriate, inappropriate!"

General Zhendong frowned. She chose this place to camp, one for the purpose of concealing, and the other for the convenience of water attacks.

This place is not far from the gate. If you can really successfully store water, it is easy to catch the thief off guard.

Unexpectedly, Pei Xiu rejected it.

"This is the most suitable place. If it is not suitable, do you have any other choice?"

Pei Xiu took out a tart cloth bag from his arms and opened it carefully. It contained a map he drew in the past few days.

There are densely painted symbols that only he can understand.

"Please look here, General. Where did we pass by yesterday?" Pei Xiu pointed to a place on the map, probably because she was afraid that General Zhendong would not understand it, and then she deliberately circled it out with a pen:

"Here, just next to the Baoqiu Water, there is a pool of water, which is a low-lying land with extremely dangerous terrain."

(i.e., the Heilongtan in later generations)

"Do you still remember the pool of water?"

General Zhendong thought about it and a dangerous place floated in his heart, and nodded: "I have an impression."

"Yes!" Pei Xiu said with a little excitement, "that place is big enough, and the outlet of the Baoqiu water is extremely narrow."

"Just cut off the Baoqiu water in this pond, block the outlet, and wait until the water is full, and finally open the dam to release the water."

"Storing water in a deep pool is much more convenient than here, it is very labor-saving, at least much more than here."

"The downside is that it is about forty miles from the gate, which is a bit far away."

General Zhendong slapped onto the map and said immediately:

"Forty miles, not too far, just right! Then store water here."

He looked at Pei Xiu and asked, "How much manpower is needed?"

"This," Pei Xiu scratched his head with a pen. "When the student passed by, he just took a brief look. As for how much manpower is needed and how high the dam needs to be built, he still has to go there to measure it before he knows."

"Stay now!"

General Zhendong urged without waiting for a moment.

Let Zhao Guang stay and lead the team to look back and go to find what Pei Xiu said.

It took about twenty miles to go, just over an hour to walk lightly.

The previous episode was just concerned about rushing, and the leader passed by quickly without having time to take a closer look.

When I returned to Tanshui to observe, the first thought of General Zhendong was:

This is really a great place to set up an ambush!

The pool water is embedded in the folds of the main vein of Yanshan Mountain, shaped like a gap nipped out of the fangs of a giant beast.

The two rock peaks face east and west, and the rock walls are covered with longitudinal gullies, like trenches plowed out by the gods with their nails.

The Baoqiu River was tightened by the mountains here, and the river channel, which was originally thirty meters wide, suddenly shrank to five meters.

The river roared like thunder as it squeezed across the pass. The water mist that rose did not dissipate for years, condensed into blue-black moss on the rock wall. From a distance, it looked like the old scales of a giant dragon faded away.

There is a strange dark green floating on the surface of the pond all year round. When the sunlight is direct at noon, the water surface will see golden and green waves, just like a dragon's eyes opening and closing.

Thousand-year-old cypresses grow in the cracks of the rock. The trunks are twisted like spasms, but the crowns are tilted southwards. This is a unique "flag tree" in Yanshan, which is caused by the north wind outside the border for many years.

The shallows were piled with animal bones rushing down from the upstream, soaked in grayish white.

Once General Zhendong mentioned it, he could remember this place because the terrain here was too unique.

Even if she passed by in a hurry, she left an impression on her.

"General, look!"

Pei Xiu raised his eyes to observe the surroundings and suddenly pointed to a certain place.

Following Pei Xiu's point, I saw that the terrain on the north side of the Tankou was somewhat incompatible with the surrounding area, as if it was done by artificial means.

When they got closer, the soldiers were asked to clean up the weeds, and half of the rammed earth dam revealed their true colors.

"General, it turns out that a predecessor has built a dam here for a long time!"

Standing in front of the broken dam, Pei Xiu touched the still solid rammed earth. While excited, she couldn't help but wonder:

"Yes, yes, there are indeed people building dams here, but for some reason they were destroyed. But it doesn't seem like it was washed away by water..."

General Zhendong was also surprised that the dam ruins appeared here. She looked at the destroyed place and looked at the expression of clarity:

"This is being destroyed."

Pei Xiu was shocked:

"Since ancient times, water control has been a great merit. I only heard of promoting water conservancy, but I have never heard of destroying water conservancy. Who is so bold?"

"How do I know?" General Zhendong was a little impatient. "Youzhou must be able to build a dam here. You really want to know that after you capture Youzhou, you will go and check it."

However, in order not to dampen Pei Xiu's enthusiasm, she still explained it with a rare sentence:

"You all say that water control is a great merit. If Youzhou builds this dam, it will naturally not be destroyed for no reason. The most likely thing is that the Hu people went south to rob, thinking that the dam was in trouble, so they were destroyed."

If such a good place to set up an ambush, thousands of people would lose tens of thousands of people if they could make good use of the dam.

So the Hu people destroyed the dam, which is not considered a nonsense.

(According to later generations, this was built by Zhang Kan, the prefect of Yuyang of the Later Han Dynasty, when the land was stationed, and it was later destroyed by the Xianbei to go south and robbed.)

Seeing that General Zhendong was a little impatient, Pei Xiu remembered the purpose of his trip and did not dare to say more.

After a round and observation, I returned to the remains of the dam:

"Since my predecessors built a dam here, why should we pay more attention? And we can also use this half of the dam to save some trouble."

After saying that, he took out the tools on the spot and began to measure the dam. There were also students from the academy in the army who could help Pei Xiu.

After the measurement was completed, there was another intense calculation.

When the results came out, it was already night.

"General, with this half of the dam, it originally took three days to build the dam, but now it only takes two days."

Pei Xiu held a piece of paper in his hand and handed it to General Zhendong, "In addition, it only takes five days at most."

Anyway, it is a temporary dam, so there is no need to think about too much.

Just simply calculate the project volume and it's almost done.

General Zhendong glanced at the paper and saw that there were numbers on it, and some of them were unique formulas of Alang Master.

She didn't reach out to take it, but just asked:

"How many people are needed?"

"It takes about one thousand people to build a dam, and if there are more, it can't be squeezed. In addition, it takes two thousand people to log and weave baskets to load sand and stone."

"Total three thousand?"

"right."

"Six thousand people are divided into two groups of people, and they are carried out in turn. I want you to build this weir as quickly as possible."

As for the remaining one thousand people, they will scatter out to monitor the possible enemy situation.

Anyway, it is nearly one day away from the gate, so don’t worry too much about being discovered by the thieves at the gate.

"Remember, the more water you store, the better!"

"Students understand."

It is only a five-meter-long mountain pass, with 6,000 people, which is more than enough.

Plus, the college-born generals and schools help.

It makes Pei Xiu confident.

He is really familiar with civil engineering.

Not only him, but many students from college are also familiar with him.

Mr. I am right. Civil engineering knowledge is of great use, whether it is governing the people or in the military!