Digging from a stone's throw to the bottom of the city walls, one or two hundred people took turns to work non-stop, at least in the middle of the night. It is not the first time that Huang Xuangan has done this, the Shenwu Army has already accumulated considerable experience when digging holes in Hedong and Henan to bomb the city, and when forming the preparatory school, these scattered experiences have been summarized together, and even the specific data of various situations are very detailed, even if there are uncertain details, the instructors of the preparatory school have also done many experiments in the suburbs of the city to get first-hand data.

Before Huang Xuanyu was recruited, he had been serving as an instructor in the preparatory school, and at this moment, many previous experiences played a major role. Many people don't understand, and even worry, can they really break the iron gate overnight by doing this?

Digging tunnels into the city is only suitable for raids, and if discovered, they only need to send a small number of soldiers to guard the exit. However, Huang Xuan not only arranged for thousands of people to dig tunnels, but also arranged for more than 2,000 people to line up and wait for battle a stone's throw away from the Iron Gate. The long line of torches stretched for miles, and from a distance in the darkness, the sound was quite terrifying. In fact, this is just a tactic of attacking the heart, and most of the torches are *on the ground, in order to achieve a bluff effect. It is very difficult to find the thieves inside the Iron Gate Pass if you don't go to check it in person.

On the one hand, they are secretly digging tunnels, and on the other hand, they are bravado, and those who should be acting secretly are swaggering and swaggering, are they still afraid that the thieves inside the Tiemen Pass will not be able to discover the tunnels? Moreover, the thieves in the Tiemen Pass are seven or eight out of ten Anxi rebels and have very rich combat experience, so there is a greater chance of discovering the behavior of the Shazhou army in digging tunnels.

Huang Xuan rarely explained to his subordinates, he only needed his subordinates to act according to military orders, and everything would develop smoothly in the direction he wanted.

Just when it was in full swing, Tanma hurriedly reported:

"I've found Dugu Changshi!"

"Great!"

After Huang Xuan shouted excitedly, he asked again:

"Has Dugu Changshi ever been injured?"

Tanma replied:

"There are a lot of injuries on the body, and they shouldn't be fatal!"

Judging from this, Dugu Yanjing's injury should not be light, but as long as there is no worry about his life, there is still a possibility of recovery. However, Huang Xuan did not go back to visit Dugu Yanjing, but ordered someone to pass on an order to take care of him, and to go all out to treat him and make sure that he recovers as soon as possible.

The reason why he didn't go back was because the situation in front of the battle needed Huang Xuan more, according to the previous estimate, the tunnel would be dug to the designated location under the city in one or two hours, and there must be no mistake at this moment.

However, even if it was also a group of 200 people digging tunnels, the progress was also first, and the group near the north actually dug to the designated location half an hour earlier than expected, and after repeated measurements, after confirming that it was correct, Huang Xuan ordered * to be poured into the oversized wooden box prepared in advance.

This kind of wooden box is nearly one zhang long, two feet three inches wide, less than five feet high, the reason why this kind of long strip is made, is also out of the consideration of the difficulty of digging tunnels, the width of the wooden box increases by one foot, the width of the tunnel should be expanded by one and a half feet accordingly, it is necessary to leave enough margin, the wooden box can be lifted to the designated position through the tunnel. The tunnel is expanded by one and a half feet, and the man-hours consumed will also be greatly increased, so after a combination of various factors, there is a box of this size.

The Turkic elder named Lost Bi was also watching the battle, he was specially invited by Huang Xuan, and the purpose of this battle was to increase the confidence of these distracted Turks in *.

It is inexplicable to see that as early as forty years ago, he was also a few warriors among the Turkic tribes, and fought with the steppe tribes, the Tibetan people, including *. This method of attacking the city to Huang Xuan alone is very rare.

Although he was already old, his temperament was still very straightforward, so he asked without hesitation:

"Since the general is trying to break the city by digging tunnels, he should be as quiet as possible to avoid detection, so why did he send two or three thousand people to demonstrate there so loudly?"

In fact, this question is also the question of the vast majority of military generals, and it is really the first time I have seen such contradictory tactics to attack the city.

Huang Xuan still sold Guan Zi until the mystery was solved, and he didn't explain it in detail, but just told him to lose it:

"There must be a sense to do this, and after a while, you will know why!"

Huang Xuan said it so easily that he began to doubt his own thoughts, could it be that he had not been on the battlefield for many years and could not understand the tactics of the young man? However, after thinking about it several times, he still couldn't figure out the key reason, and he couldn't help but feel a little disappointed in his heart, this young Tang general was obviously not as wise as he imagined, and what he did tonight was absolutely stupid.

Everything that should be reminded has already been reminded, and General Tang Ren refuses to listen to the advice, so he can only wait for him to touch the nail. Even if a siege method like this fails to meet the consequences, the casualties will not be too great, and it will not be too late to make a good plan tomorrow after he has lost his spirit.

In the opinion of Bibi, * the generals of these years have not been as good as before, and it is difficult to have famous generals like Wang Zhongsi, Ge Shuhan, Gao Xianzhi, and Feng Changqing, which can be seen from this conceited and somewhat stupid young Tang general.

At the same time, Bi Bi was also worried, was it a bit hasty to entrust the life and death of the whole clan to this young Tang general? It's a pity that he has no other way, and before entering the Western Regions, this is their only choice.

Of course, Huang Xuan didn't know that the Turkic old man around him was secretly slandering himself, and at this time, his attention was already all on the action of the explosion.

Carry the long wooden box full of * into the tunnel in advance, and move it to the designated position little by little. Two finger-thick ropes were led out of the tunnel from the long wooden box, and the reason for this was to prevent the fire rope from being accidentally extinguished, and one more fire rope was equal to one more insurance.

This was a test explosion, and the ultimate purpose was to test whether the current * capacity was sufficient to blow up the rammed earth walls of the iron gate. After another half hour of preparation, everything was finally ready. Regardless of whether the other tunnels were excavated or not, all the soldiers in them were ordered to withdraw, which was to prevent the explosion from shaking the tunnels and burying the soldiers in charge of digging in the low.

The two ropes were ignited by the torches, and the ends of the ropes sizzled and sparked, slowly burning towards the interior of the tunnel.

The Turkic elder was puzzled by what was in front of him, and he couldn't understand why he had smashed some black powder cubes and put them in a wooden box, and then dragged the wooden box into the tunnel, until two finger-thick ropes were lit and burned into the tunnel, he still didn't understand what these things were used for.

After a "long" wait, he suddenly noticed a slight tremor under his feet, and then this tremor became more and more violent, and a thunderous sound seemed to come from the ground. He didn't understand what was going on, the darkness obscured his vision, and he tried to see what was happening in the distance, but to no avail. However, the sound of intermittent howling and cursing could be heard from afar.

Something must have happened, and the thunderous sound may have come from the tunnel.

Huang Xuan ignored the doubts and surprises in his heart, and while ordering people to check the damage to the rest of the tunnels, he threw several fire thunderbolts with a makeshift stone cannon. Fire thunderbolts are made from flammable materials such as fire oil, and although the materials from Hexi to Anzai are limited, some are still made.

When a thunderbolt of fire fell near the walls of the city, it immediately ignited a raging tongue of fire. Together, the darkness was immediately dispelled, and the city wall of the Iron Gate Pass was revealed in the reflection, and before it was finished, it was not enough to be surprised by this strange thing that caught fire out of thin air, and it was discovered that the originally intact Iron Gate Pass city wall actually collapsed.

At this point, he finally understood everything he had seen before, not that the young Tang General was stupid, but that his own knowledge was far behind, and a dull sigh came out of his chest.

After the inventory, only one of the tunnels excavated at the same time collapsed close to the explosion point, and it seems that the situation is useless, and everything else is intact.

Before the fire oil and other flammable materials of the fire thunderbolt burned out, the scouts of the Shazhou army observed the reaction of the city as much as possible, and they obviously showed no signs of going out of the city to fight back, but repaired the small section of the city wall that collapsed and damaged as soon as possible. Rows of wooden shelves were lifted to the top, used as barriers to ward off the footmen.

Being able to react so quickly and skillfully deal with the collapsed city wall is enough to see that there are soldiers with considerable experience in the city.

Huang Xuan waited quietly, waiting for several other tunnels to be prepared, the effect of the explosion would be far beyond the reach of this test explosion, once the explosion was successful, it would be the death of the thieves in the Iron Gate Pass.

"Order, prepare the infantry in formation, once the explosion is successful, it will be the time to attack the city!"

The military order was passed down at a very fast speed, and the soldiers who were waiting for the middle of the night were already impatient, and the scene just now had explained everything, and the morale was unprecedentedly high at that moment.

Not only that, but the teams of each team are not forgetting to cheer for their own soldiers.

"There are less than 1,000 thieves in the city, as long as the city wall collapses, the kings rush in to chop melons and vegetables......"

In the meantime, some scouts were sent to the city, but they were quickly driven back by the Shazhou army in charge of vigilance, and tried to cover with arrows on the city wall, but it was as dark as ink, and its effect was minimal.

Half an hour later, the eastern sky was faintly white, all preparations were ready, and with a sharp and long whistle, more than a dozen fire ropes were lit at the same time, sizzling sparks slowly forward in the darkness......