So although there were hundreds of vehicles and thousands of boxes of materials, the engineer brigade was assembled smoothly and quickly.

Looking at these big guys that appeared in front of the whole army after they were assembled, most of the soldiers of the Central Army did not know and had never seen them.

Only officers of all levels who have studied in military schools and soldiers of the engineer brigade know these big guys, and they are called trebuchets, also called trebuchets.

The catapult is a super weapon that can throw dozens or even hundreds of catties of stones hundreds of steps away through the principle of levers.

Ma Jun designed and manufactured two kinds of stone throwers, one is a slightly smaller trebuchet, which requires manpower to pull and release, and the one that throws stone bullets is named stone cannon.

The stone cannon was mounted on a rotatable gun carriage with four wheels mounted under the gun carriage, which could be moved by human or animal power.

The stone cannon made by Ma Jun is still very powerful, and it can shoot a stone weighing 30 catties out of a distance of 150 zhang.

Lü Bu arranged these stone cannons on the inner city wall, with an interval of 100 zhang, for a total of 40 cannons.

And for these stone cannons, a lot of stone bullets with uniform weight and preliminary polishing have been prepared, and there are two kinds of stone bullets: 30 catties and 60 catties.

These stone cannons need special personnel to aim and cast, and each stone cannon also needs forty people to be dragged and cast, so Lu Bu trained a Han Dynasty artillery soldier in advance, temporarily attached to the engineer brigade, specifically responsible for operating the stone throwing machine.

The other type of stone throwing machine designed and manufactured by Ma Jun is even more behemoth, they are installed in the open space within the inner city wall, and each one needs to occupy a huge area and cannot be moved.

Compared with this era, the design concept of this stone thrower is advanced and abnormal, and it can be called one of the "black technologies" of Lu Bu that is no less than gunpowder.

They are counterweight lever trebuchets, which Lu Bu named heavy artillery, of course, they are all cannons next to the stone characters, and the cannon in chess is the same word.

The lever of the heavy artillery is as long as eight zhang, and the counterweight hammer is 20,000 catties, which can throw two hundred catties of stone projectiles out of a distance of 200 zhang, which is absolutely an invincible siege weapon.

Before firing, one end of the load needs to be pulled down with a winch plus a pulley and rope, and only a small number of people are needed to pull it down, and the counterweight is raised to the highest.

When you are ready, let go directly, and the end with the counterweight hammer will fall in free fall, and the stone projectile will be thrown with the trend.

Because Ma Jun's heavy artillery had an extremely long range and was a projectile, it was installed behind the city wall, and Lu Bu taught them the indirect aiming method to use the heavy artillery to attack in a curve.

However, because of the weight, it was impossible to use the base of the gun carriage to move, so it had to be fixed to the ground.

These two trebuchets had actually been researched and manufactured before the attack on Chang'an, but Lu Bu felt that their power was too great and their destructive power was amazing.

Lu Bu didn't want to smash Chang'an City into ruins, nor did he want them to be stained with too much Han blood, so he kept it hidden.

This time the battle of Tiger Prison Pass was the most important battle that Lu Bu thought was the most important battle, and he had to win, so he no longer hid his secrets.

He also hopes that this super weapon can weaken the morale of the Kwantung Coalition Army and end this civil war as soon as possible.

Trebuchets can both besiege and defend cities, and can be switched between different power and range by simply replacing stone bullets of different weights.

The types of artillery shells are actually not limited to one type of stone bullet, Lu Bu naturally has some better ideas, but it depends on how the war progresses!

Moreover, the history of the appearance of manpower trebuchets in China has been a long time, and it is difficult to guarantee that the Kwantung Coalition Army will not equip them, and the nemesis of trebuchets is naturally also trebuchets, which is also the main reason why Lu Bu took out the trebuchet to use.

The counterweight stone throwing machine is a product that transcends this era and is sure to bring surprises to the Kwantung coalition forces.

A total of 30 counterweight stone throwers have been installed, and they have not yet been test-fired, and it is not known how far the specific range will be.

Because it was a defensive battle, only 30 catties, 60 catties, 100 catties, and 200 catties of artillery shells were prepared, and when the city was really attacked, heavier shells could also be fired.

The Kwantung coalition army waited for another three days to prepare the siege equipment.

It was agreed that Cao Cao's Yanzhou army would take the lead in the siege on the first day to test the garrison of the central army at Hugao Pass.

The height of the human trebuchet is far less than that of the counterweight trebuchet, and it is installed on the inner city wall, so it is not conspicuous.

Twenty miles away, there was no telescope at that time, so it was impossible to see clearly, and it was so close that it could not be seen because of the angle.

Therefore, although the scouts of the Kwantung Coalition Army found some extra wooden shelves on the inner city wall, they thought that they had added arrow towers or watchtowers, and reported them.

And in these three days, Xu Rong's first division and Yu Ban's seventh division have arrived one after another, but Lu Bu was afraid that they would have a tiring journey, so he arranged for them to rest first and not participate in the first day of defense.

After breakfast, Cao Cao took his generals and 40,000 infantry to prepare for the first siege, and the hoplites, spearmen, light infantry, and crossbowmen were arranged in proportion.

The siege equipment prepared in the past few days has also been unveiled, the first is the ladder, which is also the most common and necessary siege equipment.

Cao Cao prepared two kinds of ladders, one was a simple wooden ladder, and an iron hook was installed at one end to hook the city wall, which was slightly higher than the city wall and about seven zhang long.

When the time comes, it will be bent diagonally under the city wall, and the brave will climb up.

The other type of ladder is much more complex, with a base that can be moved and is equipped with four wooden wheels.

The cart was covered with cowhide to protect it from bow and arrow attacks and arson, and dozens of people inside pushed the wooden cart forward.

Above the base is a wooden shelf with two ladders, one fixed to the base with a wooden frame, and the other retractable, just like a ladder used by modern firefighters to fight fires.

Thirty simple ladders were made, and only ten movable ladders were made.

In addition, five chariots were made, that is, the top was covered with cowhide, and the bottom was equipped with a very thick and heavy wooden mallet, which was pushed by human power to hit the city gate or city wall.

As for the moat in front of the pass, it is a thorny problem, because the moat of the Tiger Pass is connected to the Yellow River, so it is not feasible to dig a ditch to divert water.

The only wooden bridge over the moat, which had been destroyed by the time the Central Army retreated into the city.

Later, the state proposed two methods, one is the method of filling the ditch with negative soil, which has been mentioned several times before, but this time it is prepared, and the efficiency is much higher to fill the ditch with sandbags.

The second method is to build a wooden ladder more than ten zhang long and erect it on the moat for passage.

Of course, there is no other way, which is to repair the wooden bridge, because the large ladders and rushing vehicles are extremely heavy, and then they can only be passed on the bridge or sandbags.

Cao Cao decided to carry out the three methods at the same time, and when Cao Cao's army beat the war drums, the other princes were also fighting outside the camp.