Moments later, the young hunter was escorted into the barracks.

The old patriarch instructed: "You go back to the mountain and tell the clansmen, let them bring their tools out of the mountain, and go to the mouth of Shuangfeng to help the imperial army repair the dam." ”

The young hunter replied with a good word, and quickly left the camp and headed north into the mountains.

Later, Yang Congyi explained the situation near the mouth of Shuangfeng to the others in detail, telling everyone that the location of the dam and barrage should be adjusted, and the target of the attack should also be changed. Build a dam at the mouth of the twin peaks, block the water of the big river, you can store a large lake in the valley, and after all the enemy troops gather opposite the town of Nasuo, immediately destroy the dam and release the water, the big water will rush straight from the mouth of the valley to the south, you can drown all the enemy troops in one fell swoop, if the enemy is unlucky, not a single enemy army can escape.

When the others heard that there was such a good thing, no one was excited, and if the river was really successful, the four thousand enemies who came to Nasuo Town would be annihilated in one fell swoop, and the Xuanwei army would be able to achieve a complete victory.

"Overseer, I don't know if you have considered a question?" Yao Chang, who had been silent for a long time, suddenly asked.

"Say, what's the problem?" Yang Congyi was slightly surprised, could it be that he missed any important details?

Yao Chang said: "The enemy will arrive soon, even if we repair the dam within two days, it will take time to store water, once we start to intercept and store water, the flow of the big river will be cut off, the water level of the downstream will be lowered, and after the enemy reaches the opposite side of Nasuo Town, even if there is no boat, he can quickly cross the river and move eastward." The only way to do this is to send a force to begin approaching them and delay their march, or to deploy a force in the town of Nassau to confront them face to face and delay the storage of water. Whether it is close to maneuver or confrontation, we are all very dangerous because of the disparity in our forces. ”

Yang Congyi nodded, this is indeed a problem, even if the river is large, it takes time to store water, if during the impoundment period, the enemy just arrives, in the face of the dry river, the enemy will quickly cross the river and move eastward and leave Nasuo Town, so it is necessary to send people around, or confront the enemy across the river in Nasuo Town.

The confrontation across the river seems to be the best, it can block the enemy just on the other side of the river, in front of the southbound water, but once the enemy finds that the water level of the river is lowered and dry, he will inevitably make a detour to cross the river, and in the end it is likely that the Xuanwei army ordered to confront the confrontation will be destroyed, and the enemy will also flee.

"Yao Chang is right, if we intercept the river at the mouth of the twin peaks, we must keep the enemy in the town of Nasuo before the dam has enough water. We are to send a battalion of men and horses to cross the river at once, to harass and block the enemy's march, to delay their arrival at the town of Nassau, at least two days, and when the water is stored, we will obey the order and let the enemy reach the town of Nassau. Who gets this errand? Yang Congyi asked after thinking for a moment.

"I'll come." Su Zhong and Pan Cheng rushed almost at the same time.

"No matter who you two go, you can actually complete the task, but Su Zhong has fought with Li Yueren and is more familiar with them, so it is better for Su Zhong to go this time." Yang Congyi was very satisfied with their courage to show the Lord.

"Xie Jianjun, I'll leave now." Su Zhong got up.

"Second Su Lao, this is cheap for you, next time you have such a good opportunity, don't rob me, otherwise don't blame me for turning my face." Pan Cheng got up and patted him.

"Okay, you take one person with you, this battle is mainly harassment and delay, and it is invincible, on the premise of completing the task, ensure the safety of the Xuanwei army, and don't bury the lives of the soldiers for no reason. After four days, return to the vicinity of Nasuo Town, pay attention to the fireworks signal from the north, and immediately hide the sight of the fireworks and retreat to the mountains and forests to the west. Yang Congyi instructed.

"I see, promise to complete the task." After speaking, Su Zhong left the barracks quickly, full of confidence.

"Let's act immediately, the whole army will go north to the mouth of Shuangfeng, build a dam and store water."

Yang Congyi gave an order, and the generals immediately took the Xuanwei army into action and went north along the river, preparing to build a dam.

As soon as the Xuanwei army arrived at the mouth of the twin peaks, they set up camp on the hill and immediately began to cut down the big trees that were thick and thick, and no matter how the dam was built, the big trees were indispensable.

Yang Congyi took Yao Chang and others to carefully observe the terrain of the river bay and the width of the valley mouth on the hills of Shuangfengkou, and they wanted to build a dam that could not only store water safely and quickly, but also destroy it at any time.

After discussing for a long time, there was finally a specific dam plan, and Yang Congyi drew a brief construction drawing.

According to their idea, with dozens of zhang high giant trees from the hill, obliquely inserted to the bottom of the valley on the other side of the river, both sides start at the same time, only in the middle of the valley to leave a few zhang wide outlet, and so on in both directions obliquely insert a four-zhang wide foundation dam body, then the slightly smaller trees are thrown into the river, the water outlet is blocked, the water flow outside the valley is small, you can dump the sand and gravel from the middle of the gap of the dam body, use the sand and gravel to fill the river with reduced flow speed, and finally build a high five zhang long, ten zhang wide and four zhang wooden concrete dam body, wait until enough water is accumulated, The hills at both ends of the dam were dug up and the water washed away the wood-concrete dam.

As soon as the plan for building the dam was decided, the Xuanwei army immediately began to intensify the felling of trees, and all the trees on both sides of the hill near the mouth of the river were cut down to make way for excavation.

Soon after, the people of Nasuo, who had taken refuge in the mountains from the war, arrived, and they numbered six or seven hundred men, carrying very complete tools, saws and axes for logging, hoes, shovels and bamboo baskets for digging and landfilling, and, fortunately, a few carpenters among them.

Yang Congyi gathered several principals and craftsmen in Nasuo Town, and after explaining to them the plan for the construction of the inclined wood-concrete dam, the craftsmen proposed some minor corrections.

After the correction, the dam will be more firmly built, and the speed of filling in the barrage will be accelerated, and it may not take a day and a half to repair the dam.

Due to the arrival of the Nasuo people, who brought with them the tools they had at hand, the speed of logging was further accelerated.

At the same time, the entire dam repair team also carried out a division of labor, 500 people felled wood, 600 people carried, 400 people built the foundation dam body, and the rest sewed sacks and excavated soil and stones.

With a neat slogan, the giant logs, which had been slightly processed, were dragged into the river, and one by one stood diagonally, one end stuck at the bottom of the river, and the other end on the hill where the pit had been dug.

In less than half a day, more than 100 big trees are obliquely inserted left and right, the foundation dam body is built, looking down from above, the trees are arranged neatly, it seems that there is no gap, but from the bottom, the gap is not small, and the river is still flowing in a hurry.

Yang Congyi and the craftsmen personally inspected the dam body, and after confirming that it was correct, dozens of slightly smaller trees were thrown into the water mouth several zhang wide, and then hundreds of sacks filled with soil and stones were also thrown in, blocking the water flow.

The downstream water flow suddenly decreased, and after a few moments, the river had bottomed out and the interception was successful.

After a burst of cheers, the Xuanwei army and the people of Nasuo immediately began to fill the dam with sand and gravel trees, and at the same time piled sand and gravel on the outside of the dam to add a boost to the wooden dam.

Thousands of people took turns filling in the earth, day and night, and finally after a day, all the wood was buried under the soil, and a dam more than five feet high was built, completely blocking the mouth of the river.

During the day, the water level had risen by nearly two feet, and as far as the valley looked north, there was already a small lake in a radius of a few miles, and it was growing larger every hour as far as the eye could see.

The Xuanwei army and the people of Nasuo, who had not rested well for two days, gathered on the hill, looking at their masterpieces, excited. This project should be the fastest, best, and most willing one they have done in their lives, and it is also the most satisfying one.

After the dam was stopped, everyone returned to the camp half a mile away to rest, and the rest of the time was spent waiting for the water level to slowly rise to the point of submerging the dam.

The flow of the river was so great that after another day and night, the water level was close to four zhang, but it was still about two zhang high from the submerged dam.

Originally, it was expected that the dam would be five zhang high, but after the actual construction of the landfill earth and rock, the height was close to six zhang, the higher the dam body, the more water storage, once the dam was destroyed, the impact on the bottom of the downstream plain was also greater.

But the dam body is high, the need for water storage time is more, the first half a day, the water level can be raised by a zhang, to the back of a day and a zhang, and then a day and a night before a zhang, if you want to think that the water level rises to overflow the dam body, at the current speed is really unpredictable, the water level is raised a little, the water area will increase a lot, and the speed of the water level will be greatly slowed down, because I don't know how big the upstream valley bottom is, when it can be filled with water, Yang Congyi has no bottom in his heart.

"Prison army, or I will take a battalion of people to pick up Su Lao Er." Pan Cheng saw Yang Congyi standing on the hill by the water, looking at the water and being distracted, knowing that the prison army was worried about the storage of water.

Yang Congyi turned around and said, "It's okay, the time we agreed with him is running out, but the water level is estimated to be a few days away." You take a battalion of men south to meet them, continue to maneuver, and after three days hide their tracks, withdraw directly to the hills to the west, and let the enemy advance eastward. Don't fall in love with war, the water is ruthless, be very careful. ”

"Rest assured." After Pan Cheng received the order, he quickly went back to rectify the team.

Half an hour later, Pan Cheng led a battalion of Xuanwei troops through the dam body, reached the west bank of the river, and under the leadership of the hunters, went straight to the south.

After another day and a night, the water surface is finally only one zhang high from the dam body, but the water level of this height is not a matter of one or two days for it to rise.

Yang Congyi went to the river several times a day, and every time the water level rose a little, he felt at ease, but with the expansion of the water, the speed of the water level rising further slowed down, and when it rose less than a foot deep in half a day, he was suddenly anxious.

Two days have passed since the time agreed with Su Zhong, and half of the time agreed with Pan Cheng has passed, how should this be?

The water does not overflow the dam body and washes away the soil and rocks outside the dam, and even if the pit is dug to fix the giant trees, the small dirt and mountains outside the dam cannot be pushed away by the force of water alone.

In another day, it really can't be done, so we can only dig a ditch in the middle of the dam and divert water to wash away the soil outside the dam, but in this way, the water potential may hit some of these buttons, but the amount of river water that has been accumulated for four or five days is not small, and although the enemy army is not 100% sure, there should be no major problem.