Liao Loach was not angry that Xia Dagen and Xiaogen had deceived him under the pretext of illness, but he was so anxious to learn that the two brothers were going to follow Dong Hu into the mountain. He had a very good relationship with the father of the two brothers, and since he was an orphan since childhood, he has always regarded the two brothers as his own. Now that I heard that the two brothers were going to Wanjiazhai, thinking that they were also alone, they proposed to defect to the Thunderbolt Army, which made Dong Hu overjoyed, and even agreed. Ouyang Xuan mentioned many times at the high-level meetings of the Perak Army that it is very important to build a strong naval army in the future to develop down the mountain and even defeat the Mongols. Liao Loach is not only proficient in water, but also a good hand at boating, which is exactly the shortage of naval talents in the Perak Army.

When Dong Hu and his entourage returned to Wanjiazhai, it was the 25th day of the lunar month. At this moment, the Jiguan Mountain is drifting with goose feathers and heavy snow, the weather is very cold, but the villages are full of steaming and busy scenes, young people are in military exercises, women are spinning and making shoes, the sound of reading aloud in the school hall, and the jingling sound in the factory, Liao Loach and the two brothers sighed again and again. What surprised the three of them even more was that Ouyang Xuan, the leader of the Thunderbolt Army, was not at all the fierce and vicious appearance of the legend, but a scholar-like young man with very short hair, with an enthusiastic attitude and kind speech, without the frame of an official master at all.

After talking, Ouyang Xuan asked Liao Loach to report to the officer teaching company of the garrison camp. Accompanying him to report for duty was the messenger Le Quan'an from Xinjin City. In the past few days in Wanjiaping, Le Quanan saw that the military discipline of the Perak Army was strict and orderly, and the political clarity in the mountains was changing day by day, and he also asked to join the Perak Army. Ouyang Xuan saw that these two were proficient in water warfare and had also passed the background screening of the counter-espionage department, so he trained the two as the backbone of the water army in the future. As for Xia Dagen and Xiaogen, the two brothers were sent to the school, and after the study was completed, they would make plans.

On the 29th of the lunar month, the messenger of Xinjin City came to Wanjiazhai again. The messenger brought two documents, one of which was an official document from the imperial court regarding Ouyang Xuan's appointment as the county order of Yongkang. The other is an order written by Pan Commander himself, requiring the Perak army to attack Chongqing on the 15th day of the first lunar month. If it is necessary to fight Yongkang City before this, it is up to Ouyang Xuan to decide. After the messenger sent the letter, he left in a hurry, but when he came, only four of the five people returned, and a small colonel named Yu Lao Dig stayed in Wanjiazhai. This is because the attack on Chongqing Mansion City will be the naval army of Xinjin City, which needs to contact the Thunderbolt army through flags and fireworks signals, so Pan Tongzhi specially sent Yu Lao to be the liaison officer between the two armies.

During this time, the Thunderbolt army was also fighting for the attack on Yongkang and Chongqing. In terms of military production, folding shields, spears and rattan armor have been basically equipped, and only a little more production is needed to supplement the loss. Artillery shells and grenades are also sufficient, but there is a large gap in the equipment of artillery, especially the light artillery is only 50 percent of the number of field battalions, and the production of new mine mercury grenades is also small, so it can only be prioritized for the scouts under Dong Hu's command. As for the muskets, dozens of muskets have been produced, although the design of these muskets adopts the advanced concept of breech flint proposed by Ouyang Xuan, but due to the restriction of the production process, although the power is extremely high, there is a large gap with the bow and arrow in terms of rate of fire and accuracy, and the production efficiency and scale production capacity also need to be further improved. In terms of logistical supplies, there were plenty of flour and dried meat, as well as plenty of cold-proof clothing, knife wounds, and bandages.

In terms of offensive tactics, the Perak Army Staff also conducted a number of exercises. In order to enhance the ability to command campaigns and tactics, Ouyang Xuan transferred personnel from all over the army who had both education and combat experience to form a staff department. According to the operational plan of the General Staff Headquarters, the six companies of the field battalion were mainly responsible for the attack out of the mountain, and the garrison battalion and the internal guard battalion only had to assume auxiliary functions. Among them, three companies of the field battalion went forward to attack, and the other three companies stayed in Yokohara Village as a reserve, alternately attacking and covering each other. Regardless of whether it is attacking Yongkang City or Chongqing Mansion City, it is necessary to use Hengyuan Village as a support base, so the General Staff proposed to build a fortress in Hengyuan Village as a strong fulcrum for the Thunderbolt army to fight outside the mountain.

Ouyang Xuan was very satisfied with the general staff's battle plan, but vetoed the proposal to build a fortress in Hengyuan Village. In fact, the construction company has already completed the design of the Hengyuan Fortress, and the cement, iron bars, stones and logs required for the project have also been prepared. Historical knowledge told Ouyang Xuan that now was not the best time to build a fortress. He remembered that Pu Zezhi's counterattack on Chengdu would be a crushing failure, and not only would the entire western Sichuan be captured by the Mongol army, but in the next two years, even Yazhou west of Qiongzhou and Jiezhou and Yanzhou as far as the Tibetan region would fall into the hands of the Mongols. Hengyuan Village is connected to Yongkang and Qingcheng County in the north, Dayi County and Qiongzhou in the south, and down the river to the east to reach Chongqing Fucheng and Xinjin County. Although the concrete fortress was extremely defensive, it could not withstand the continuous siege of a large number of enemy troops. With the current military and economic strength of the Thunderbolt army, it cannot withstand a long-term war of attrition. For this reason, he is ready to fight a quick decisive battle, and after taking the cities of Yongkang and Chongqing, he will not defend them, but will transport the population and materials back to the mountains as much as possible, and lie dormant quietly under the protection of the mountains, waiting for the right time to attack again.

After the fifth day of the first lunar month, the military operation to attack Yongkang City began from Hengyuan Village. Under the protection of two companies of the field battalion, the 300 workers of the construction company made use of the dilapidated buildings of Hengyuan Village and set up an advance base within three days. The base was protected by a staggered trench and a breastwork, with artillery positions and improvised lookout towers at regular intervals, and not only food and ordnance warehouses and barracks, but also medical clinics, wells, and latrines. Although these facilities are simple, they all have basic functions. On the 9th of the first lunar month, the remaining four companies of the field battalion and the officer training company of the garrison battalion were stationed at the base under the leadership of Ouyang Xuan, and the materials needed for the operation also arrived in a steady stream from the mountains. Actual combat is the best way to teach, so Ouyang Xuan thought about it again and again, and still brought out the teaching company. The attack on Yongkang City was commanded by Cao Ergou, and the troops were the 135th Company of the Field Battalion and the Teaching Company of the Garrison Battalion. Ouyang Xuan led the 246th Company to sit in Hengyuan, acting as a reserve and protecting the rear, while the guards on the grain road and in the mountains were in charge of Yu Zhu's garrison battalion.

Before dawn on the 10th day of the first lunar month, Cao Ergou set off towards Yongkang City with his men and horses. Artillery is the most important combat force of the Thunderbolt army, and it is also the most vulnerable and vulnerable military unit, so Cao Ergou placed it in the middle of the marching array, tightly protected by spears and giant shields. The army of 400 men was a small number, a mile long on the official road, half of which was carried by wheelbarrows transporting artillery and ammunition. The wheelbarrow could only be used on the plains, and the artillery of the Thunderbolts could only be transported by hand on the rugged mountain roads, which was very difficult. These wheelbarrows were the grain trucks of the newly annexed army last time, and the carpenters of the industrial company improved and strengthened them to make them more suitable for the transportation of artillery, which greatly increased the mobility of the field battalion, which allowed Cao Ergou and others to arrive outside the west gate of Yongkang City before noon.