Artik's subordinates, after receiving the order, immediately began to prepare, because the city is relatively large, if you really dig a circle along the city inside, the manpower and material resources consumed will be too large, obviously unrealistic, but they can't determine where the enemy outside the city is digging, so it is impossible to carry out targeted confrontation.

Therefore, it is urgent to find out the location of the enemy digging tunnels outside the city as soon as possible, and it is actually very simple to solve this problem, only need to dig a few more deep pits under the city wall, and then bury the empty vat, cover the top of the vat, and send people to listen to the movement for twelve hours without interruption, as long as the enemy outside the city digs near the city wall, you can hear very clearly, so that you can determine the location of the enemy digging the tunnel very clearly.

This technique appeared a long time ago, which is enough to show that the wisdom of the ancients was still very powerful, knowing how to amplify the sound of the underground and how to determine the direction of digging tunnels.

After discovering the location of the enemy's tunnel, you can take various means such as digging, releasing water, releasing smoke, and releasing fog to eliminate the enemy digging the tunnel in the tunnel, thwart the enemy's siege attempt, and achieve the final victory.

After the expansion of the city of Maia, the area of the city wall is relatively large, and in order not to miss any direction, a large number of water tanks must be placed on each side, if the spacing is too large, it may not be easy to hear.

There were a large number of water tanks in the army, but they still could not meet the needs, so they had to borrow them from the people's homes temporarily, after all, they were to guard the city, and the people naturally would not object.

More than a thousand deep pits were soon dug in the city, with an average spacing of only a few tens of meters, which was completely sufficient, and the water tanks covered with cowhide were soon put into the pits, and each pit had many people taking turns to listen to the movements, and in order to save troops, many children in the city were mobilized, their ears were better than adults, and they could hear more subtle sounds.

In order to make it easier to manage, a petty officer was in charge of every hundred water tanks, and he had a hundred soldiers under his command, as well as one or two hundred improvised children, who would not simply listen to the sounds in the water tanks, but would immediately report to the top if they found strange sounds.

In this arrangement, it only takes more than 1,000 people to listen to the soldiers and horses, and this amount of troops accounts for a very small proportion of the soldiers and horses defending the city, and it will not affect the combat effectiveness of the soldiers and horses defending the city.

After the installation of the water tank, Artik and Ibrahim went to inspect it separately to encourage the soldiers guarding the water tank not to be afraid of hardship, but to listen uninterruptedly without slackening.

Because children can't stay up late, and can't stay up late, so, during the day, more children are listening, and at night, the soldiers are responsible for monitoring in batches, a batch in the first half of the night, a batch in the second half of the night, each of them is responsible for monitoring multiple water tanks, so they need to walk back and forth, so that they can also avoid accidentally falling asleep.

At a distance of about 100 meters, patrolling back and forth and listening to the movement in the water tank, this is not much pressure, and the consumption of physical strength is not very large, and the soldiers and horses of the besieging side, if they want to dig tunnels, they will definitely not dig for a while and stop for a while, they must have been digging tunnels all the time, so that as long as they are close to the city wall, they will be discovered by the soldiers in the city.

"The soldiers have worked hard, how is it, there is still no movement at all?"

Artik, who had come to inspect it, asked.

"City Lord, our soldiers are listening day and night, and there is indeed no movement at all, it seems that the soldiers and horses outside the city are digging very slowly, and they have not yet approached the city wall."

The subordinate said.

Artik nodded and said, "I hope this is the case, you must continue to listen, and you must not be the slightest lax, in case the enemy army comes in, we will be all finished." ”

"Yes, City Lord, we understand."

The subordinate answered.

The soldiers and horses in the city were actively on guard, and at the excavation site outside the city, Qi Yad personally guided the soldiers digging the tunnels and solved various problems raised by the tunneling soldiers.

In order not to be discovered by the soldiers and horses in the city, the location chosen by Qi Yad to dig the tunnel is a little far away from Maia City, so it is naturally more difficult to dig, not only does it need to dig more soil, but at the same time, the more you dig inside, the thinner the air will be, and people are easy to breathe.

In the era when there were no blowers, how to solve the ventilation problem of the tunnel was a big problem, and if this problem could not be solved, the tunnel could not continue to dig in, otherwise, the soldiers inside would be suffocated to death.

In the years of China's anti-Japanese war, because there was no artillery weapon, in order to deal with the Japanese turrets, the vast number of working people thought of using the method of digging tunnels to bury explosives under the turrets, and as long as the fire was ignited, the entire turret would be blown up into the sky.

But when digging the tunnel, it encountered a big problem, that is, the more you dig inside, the more polluted the air, some soldiers will sleep in the tunnel unconsciously, and even cause the sacrifice of the soldiers, in order to solve this problem, at that time in all the soldiers digging the tunnel to tie a rope, until the hole is out, as long as the situation is found to be wrong, immediately pull the rope, the fainting soldier to pull out, so as to avoid the sacrifice of the soldier.

This is enough to show that in the absence of a blower, digging a tunnel will encounter the reality of lack of air inside, and even cause death.

And right now, the elite soldiers and horses under Qi Yade's command have obviously encountered this problem, and the tunnels they want to dig are longer than the tunnels dug by the Chinese soldiers and civilians in later generations, and the problems they will encounter will naturally be more serious.

"General, it's getting harder and harder to dig inside, and I can't breathe, what should I do?"

The petty officer in charge of digging the tunnel said distressedly.

Qi Yade frowned and said, "It's not that I haven't dug tunnels before, why is the problem so big this time." ”

"General, in the past, we dug the tunnel close to the city wall, but now, the location where we dig the tunnel is too far away from the city wall, we have dug five hundred steps, and now the feeling of suffocation is getting stronger and stronger, if we don't widen and enlarge the hole, it will be difficult to continue digging inside."

The subordinate said.

Qi Yad shook his head and said: "The current tunnel is already very large, it can accommodate three people walking side by side, if you continue to increase the entrance of the cave, it may cause the collapse of the tunnel, if so, it will be bad, you can think of something else." ”

"General, in addition to enlarging the hole, another way is to make some ventilation holes above the tunnel, with this ventilation hole, it will not be too stuffy inside."

The subordinate said.

Qi Yad said: "It's okay to get some air holes along the way, but the air holes can't be too big, otherwise, it will be easy to be discovered by the enemy, and it shouldn't be difficult to throw a hole above the tunnel with a spear!" ”

"This is not difficult, but because there is a lot of sand on it, it is necessary to use a hollow bamboo pole for support, and only in this way can the ventilation holes be truly breathable."

The subordinate said.

Qi Yade frowned and worried: "If it is supported by bamboo poles, it will be too obvious, and the soldiers on the city wall will find out." ”

"General, if there is no bamboo pole to support, the sand will block the small holes, and it will not be able to breathe, and the small bamboo poles, if they follow far away, should not be discovered, because this target is too small, and it looks like a needle from a distance."

The subordinate said.

Ziyad nodded, "Okay! Let's try a few, and I'll look at them from a hundred paces away. ”

"Yes, General."

After receiving the order, the subordinates immediately entered the tunnel with various tools, and at the position of a hundred steps into the tunnel, smashed a hole upward, leading to the outside, but when the spear was unloaded, the hole was quickly blocked by sand, and then, they used hollow bamboo poles to stuff the hole just made, so that it was easy to do, and they immediately breathed the fresh air outside.

The subordinates who completed the task immediately evacuated the tunnel and went to report to Qiyad, who was standing on a high place outside, and had already seen the bamboo pole sticking out of the ground, although it was not very obvious, but it could still be found, as long as it was carefully observed.

The main problem is that the open space outside the city is full of sand, without a little vegetation, and a bamboo pole suddenly appears in a large area of sand, just like a needle on a piece of white paper, it is still obvious, although the color difference between the iron needle and the white paper is not large, but it is still easy to find.

"General, we're done, can you see it?"

The subordinate asked.

Qi Yade pointed to a small section of bamboo pole exposed from the ground in the distance, and said, "Don't you know how to look at it yourself?" ”

"It's so small, you shouldn't notice it!"

The subordinate spoke.

"No matter how small it is, it can be found, go and pull the position of the bamboo pole down a little, the less exposed it is, the less it is easy to be found, and it is best to be level with the ground, so as to hide yourself to the greatest extent."

Ziyad spoke.

"Yes, General."

The subordinates hurriedly went to prepare, and pulled the bamboo pole down according to the requirements, but as long as the sand fell, they moved it up again to ensure that the height of the bamboo pole was just level with the ground, so as not to expose the ground abruptly, and hide themselves well.

"General, if it's done, can you still see it?"

The subordinate ran out of the tunnel and asked excitedly.

Qi Yade happily pointed to the distance and said, "There is no trace of it, yes, well done, let's go and have a look." ”

They walked a hundred steps away, looked at a small black hole exposed on the ground, and shouted at the horse, and the soldiers below immediately responded and said what was going on.

"It seems that this method is feasible, as long as there are more vents like this along the way, it can solve the situation that the tunnel can't be penetrated, and put a vent every fifty steps, this should be enough."

The subordinate said happily.

Qi Yade said with a smile: "Then what are you still doing in a daze, hurry up and prepare!" As long as there is enough air, the soldiers working inside can dig the tunnels faster. ”

Soon, Ziyad's subordinates began to punch holes in the ground along the tunnel, in order to prevent detection, the small holes were small, and the bamboo poles were level with the ground, which was difficult to find, at least, it was difficult to find them fifty paces away, and it was impossible to see such holes at all a hundred paces.

Of course, Ziyad would never have dreamed that what they thought was a cautious behavior would have been exposed a long time ago, and the three cavalrymen who broke through the defense and entered the city had already told Altic what they had discovered, and the soldiers and horses in the city had already begun to guard against their tunnel attacks, so their attacks would not be effective, and returning would cause heavy losses to themselves.

After the air problem in the tunnel was solved, the speed of digging tunnels under Qi Yade's soldiers and horses increased significantly, several times higher than the previous speed, after all, when the air was insufficient, there could only be a few soldiers working inside, and if there were more people, it would cause the air consumption to intensify.

Now by punching holes in the tunnel, the air quality in the tunnel has been greatly improved, so that more soldiers can enter the tunnel to work together, the front soldier is responsible for digging, and the back soldier can transport the excavated soil, thus greatly improving labor efficiency, so that the progress of digging the tunnel is greatly improved.

As the progress of digging tunnels increases, the tunnels become closer and closer to the city walls, so that the soldiers who are in charge of listening in the city can hear some movements.

The vat closest to the enemy's tunnel was the first to hear a strange sound, but because of the distance, the sound was not very clear, but it was possible to hear the sound.

After hearing the movement, the soldier in charge of the listening was very excited and immediately reported to Artik.

Knowing this, Artik personally went to the location of the vat and listened carefully, and there was really a sound, and his old ears could hear the sound, which showed that there was really movement.

"How many vats can hear movement?"

Artik asked.

"City Lord, five or six water tanks nearby, you can hear the sound, but this one voice is the clearest, and the left and right ones are not as clear as this."

The subordinate replied.

Artik nodded and said, "That's right, it seems that the location of the enemy's digging tunnel is in this direction, let's go to the city wall and have a look." ”

After saying that, he led a group of people up the city wall.

Standing on the city walls, the Artiks could see the enemy camp in the distance, where the enemy had built siege engines, and thousands of enemy cavalry patrolling around.

"City Lord, the siege equipment camp in front is the closest to us, and it seems that the entrance to the tunnel is in the camp ahead."

One of the subordinates said.

Artik smiled: "Ziyad is really patient, he actually started digging the tunnel from such a distance, dig it!" Let them dig slowly. ”

After that, he picked up the telescope and followed the possible tunnel route to conduct a careful search.