The result of the first large-scale collision between Wang's cavalry and the Thunderbolt cavalry made both sides jealous. Since then, Cao Ergou has also become cautious, marching slowly all the way, approaching Zitong City step by step. Although Wang's Mongolian army launched several surprise attacks in the process, they did not take advantage of it but suffered heavy casualties, and could only watch as the first division forced under Zitong City.

During the march of the 1st Division to Zitong, the 2nd Division was not idle. In order to involve the Mongolian army, Huang Dagen, on the one hand, carried out non-stop harassment and night attacks with small-scale troops, and on the other hand, ordered to hit the outcropping Mongolian army with cold guns and cannons, so that Wang's Mongolian army was in a tense state at all times. In addition, Huang Dagen also sent more people to transport ammunition, and even brought more than a dozen light trebuchets. In his opinion, since the power of the shells is not enough, it is necessary to make up the numbers.

Wang's Mengjun was not idle. After seeing the power of the Thunderbolt weapons for themselves, they knew that Niu Ling and Liu Heima were unjustly defeated. Wang's Mongol army also learned that civil fortifications were the best way to deal with artillery, and immediately desperately dug trenches and built earthen walls outside and inside the city. On top of the city gate tower and city walls, the Mongolian army built a large number of anti-artillery fortifications with sandbags and wood, and hid in them for defense. These civil fortifications greatly weakened the effect of cold guns and cold guns.

After successive raids on the 1st Division on the march were fruitless, Wang's Mongol army threw its energies into digging trenches and building earth walls. In addition to the remarkable effect of the civil fortification defense and artillery bombardment, it was also because of the greater sense of oppression brought by the 1st Division. As a matter of fact, the strength of the First Division and the Second Division are the same, and although their combat effectiveness is stronger, there is not much difference between them. The reason why Wang's Mongolian army felt this way was because they brought heavy field artillery this time.

The official road from Yanting to Zitong is much easier than the ancient Shu road from Mianzhou to Zitong. More importantly, the 1st Division could also transport a part of the heavy grain and grass by water. Although the dry water in the winter made it impossible to transport heavy medium and heavy artillery in the Zishui River in Zitong, it was possible to transport grain, grass and ammunition in small boats. The rare narrow shallows can be crossed with half a load or dragged by a fiber rope.

Waterways not only carry large volumes, but also save time and effort. Cao Ergou mobilized a large number of small boats to transport grain, grass and ammunition, freed up valuable transportation capacity to haul heavy artillery, and even had spare capacity to transport dozens of light trebuchets. These trebuchets were left behind by Yang Dayuan when he fled in Pengxi Village. In fact, Wang's Mongol army also saw the threat of these heavy artillery and trebuchets. The targets of their several attempted raids were all directed at them.

Just when Cao Ergou and Huang Dagen were meeting, Ouyang Xuan also quietly rushed to the front line of Zitong, and there were still ten days before the Spring Festival. He did not come here to personally command, nor to supervise the battle, nor to experience the atmosphere of the battlefield. At present, the Thunderbolt army has been fighting for almost half a year, and although the morale is still high, it is inevitable that there will be some impatience. Ouyang Xuan was to prevent the soldiers from rushing to attack in order to go home for the New Year, and they were killed and injured in vain on the eve of the imminent victory. He came here to prepare to accompany the soldiers of the First and Second Divisions to celebrate the Spring Festival.

In addition to the staff of the General Staff, dozens of government officials, researchers, and arsenal technicians were accompanying them for the purpose of observing and evaluating weapons and equipment on the spot, and to gain first-hand information for the next step of improvement and development. This is also the fine tradition of the Perak Army, that is, everything starts from the reality of the battlefield, everything starts from the needs of the soldiers, and everything starts from winning the battle.

The meeting between the two armies, especially Ouyang Xuan, greatly boosted the morale of the Perak officers and soldiers on the Zitong front. After the convergence of the two armies, the Perak Army had seven brigades under Zitong City, with a regular strength of about 9,000 people, and a basic militia of 10,000 people. More importantly, thanks to water transportation, the 1st Division transported a large amount of ammunition and grain and grass this time. During the confrontation, the Second Division also transported a lot of ammunition from Mianzhou. Ouyang Xuan asked Cao Ergou and Huang Dagen not to be stingy, after all, no matter how valuable the ammunition is, it is not as precious as the lives of soldiers.

Seeing that the Thunderbolt army was so powerful, many generals persuaded Wang Weizheng to retreat to the Sword Gate Pass to avoid the edge of the Thunderbolt army, but he refused. He was worried that if he returned empty-handed, he would be secretly ridiculed by several uncles and cousins, and even forced to the palace. Judging from the early battle situation, Wang Weizheng was still lucky. Although Wang's Mongolian army was at a disadvantage as a whole, after all, it still had a lot of dealings with the Thunderbolt army, and even won a few small victories.

The Perak army knew that Wang was a hardcore traitor, and did not send people to persuade them to surrender before launching a general attack, but directly reasoned with them with artillery. If the cold guns and cold artillery of the Second Division were scraping the civil fortifications of Zitong City, then the heavy artillery of the First Division was peeling onions. After a few rounds of heavy artillery, the outermost Mongolian earthen wall collapsed several times. The Mongol troops hiding behind the earthen wall were either buried in the mud or were beaten into the trenches by the curved fire of the tiger squatting artillery.

The effectiveness of artillery against the enemy in the trenches is really limited. However, the Thunderbolts had not only artillery, but also muskets, grenades, and sophisticated swords and spears. Those who hide in the trenches simply throw grenades into the ditch to blow them out, and then use spears and muskets against them. This process is like whack-a-mole, although it is a little troublesome, but it can also be handled to death.

In just one day, the outlying positions to the east and south of Zitong City were captured by the Thunderbolt army. Wang's Mongol army lost more than 1,300 people, including 500 Mongol Han troops and 800 new annexed troops, which made Wang Weizheng retreat. Like the Mongolian generals such as Kipchak and Nulu, Wang Weizheng did not regard the new annexed army as his own, but as cannon fodder. He had a total of only 4,000 Mongol and Han troops, and was actually Wang's private soldiers. If the losses were too large, they would have no capital to rely on by the Mongols, and they would even be annexed by other Han armies.

What made Wang Weizheng make up his mind to retreat was the new weapon of the Thunderbolt Army. To be precise, old weapons and new tactics. After approaching the city wall, the Thunderbolt army was shocked to find that the Mongolian army's anti-artillery holes on the city wall were extremely thick, and a heavy cannon could only peel off a layer of skin. With this effect, even if the cannonballs brought by are gone, they may not be able to destroy them all. As soon as Cao Ergou and Huang Dagen combined, they put the light trebuchet under the wall, and threw the huge explosive bag on the city wall.

The siege weapons of the Mongolian army were all cleaned up by the Thunderbolt artillery, and they could only watch as the trebuchet was erected and the explosive bag fell in the air. Although this attack is not accurate, it is not very powerful. The city wall began to collapse under the huge explosion, and many Mongolian soldiers who had been hiding also died of internal injuries to their internal organs, and the rest fled one after another.

Although Wang's Mongolian army was brave, it was also bombed and its morale collapsed. After all, the passive beating is tired of parrying, coupled with heavy casualties, no matter how elite the army is, it can't resist. Seeing this, Wang Weizheng took advantage of the high wind and dark moon to secretly lead the Mongolian Han army out of the city after nightfall, and went straight to the direction of Jianmen Pass through the Cuiyun Corridor. The remaining 2,000 Mongol Han troops and 600 cavalry were his core base, and he could no longer withstand losses.

After daybreak, the newly annexed army, which had been found to have been abandoned, did not hesitate at all and immediately surrendered. At this time, in Zitong City, in addition to 3,000 soldiers of the new annex army and 4,000 people, there were also a large number of grain and grass materials. The value of the goods and free labour gained was enough to compensate for the ammunition consumption of the Thunderbolts for a few days.

Cao Ergou wanted to lead the cavalry in pursuit, but was stopped by Ouyang Xuan. As the saying goes: "Poor Kou Mo Chase", the narrow mountain road here is conducive to the Wang cavalry and not conducive to the Thunderbolt cavalry. At present, the cavalry of the Thunderbolt divisions suffered heavy casualties and could no longer withstand the losses. Besides, this time Wang Weizheng led the army to flee lightly, and it only took more than a day to escape to Jianmen Pass. For the danger here, the Thunderbolt army has no good strategy for the time being.