The "Firefox" spy network created by Su San'er now has dozens of people all over the government and military in Jiading and Meizhou, and most of them are in key and vital positions. They were all deeply disappointed by the corruption and incompetence of the Southern Song Dynasty court, and they also resented the greed of Yu Xing's father and son, and chose to join the "Fire Fox". The Perak Army advocates justice and equality, and the rule of law is strict, so that ordinary people can be fed and clothed as long as they work hard, just like the Datong world that saints yearn for. Many people in Sichuan who have deep feelings for their family and country are also inspired by the Thunderbolt Army's concept of "expelling the Tartars and recovering China" and secretly serve the Thunderbolt Army. According to Ouyang Xuan's words, these people with lofty ideals risked their heads and brought their own dry food to work silently on the hidden front, and they deserved to be real warriors.

As the captain of the guard, Su San'er naturally went to Chongqing with Yu Xing. However, although he was not in Jiading, the "Firefox" network continued to transmit political, military, and economic information to the Thunderbolt Army, and during this time, he even risked being exposed, sending a steady stream of information about Liu Da'er, Cao Zhizhou's collusion with New Zealand. After the Perak Army occupied Pengshan and Changqiu Mountains, it bordered the Meizhou territory, and the exchange of intelligence was much easier. After analyzing the intelligence of Yali in Jiading, Meizhou, Chongqing, and even the areas occupied by the Mongolian army, the Thunderbolt army not only determined that Liu Daer and Cao Zhizhou were about to surrender to Mongolia, but also figured out their plan of action.

Liu Daer and Cao Zhizhou are not only as simple as forgetting their ancestors and betraying them, but they also want to take Jiading as their capital for promotion and fortune. In the strategy of the two to surrender to Mongolia, Jiading, Meizhou, Yali and other prefectures will be presented to the Mongolian army as a letter of surrender. As for the Thunderbolt Army, their idea was to seize as much land as possible, preferably Pengshan County and Changqiu Mountain. The Thunderbolts are strong, and although these two are conceited, they are not arrogant enough to have the courage to eat the territory of the Thunderbolts. As long as these two territories bordering Meizhou are captured, they can strengthen their ties with the Mongolian army through waterways and remove the land threat of the Perak army to Meizhou. This is also the reason why Liu Daer sent people to persuade Zhou Jianshen to defect to the enemy.

Although Liu Daer and Cao Zhizhou have poor character, they are not straw bales. They offered the Bolts a plan that the best way to deal with the Thunderbolts was to build forts around the Thunderbolts and use a siege strategy to slowly confront the Thunderbolts. Although he had never personally fought against the Perak army, he also learned about the benefits of the Perak army's fortified fort and artillery from the mouths of the generals of the same clan stationed in the western part of Tunchuan, such as Huoli and Kudu. As a battle-hardened Mongolian general, he was cunning, tenacious but not arrogant, but with a rare Mongol prudence, and he did not think he could defeat the resistance of the Thunderbolts in one fell swoop. After all, the 100,000-strong army led by Meng Ge Khan could not help the fishing fortified city, but was injured and killed in the army due to the cannon wind.

The siege strategy of these two traitors made Ouyang Xuan's back break out in a cold sweat, because it hit the vital point and weakness of the Thunderbolt army. At present, the Perak army is well-fed and all industries are thriving, but these are based on the ability to obtain a steady stream of strategic resources from the outside world. If Yazhou and Meizhou Jiading fall into the hands of the Mongolian army, the input of urgently needed resources will be greatly reduced, and not only will industrial and agricultural products be drastically reduced, but the existing fiscal and taxation system will be unsustainable. The lack of food taxes attracted a large number of refugees to western Sichuan, and greatly enhanced the reputation of the Perak army, but this policy made the government extremely dependent on the income from industry, mining, and commerce.

What is even worse is that the shortage of key raw materials such as fire and mercury will cause the production of munitions to decline like a cliff, which in turn will lead to a decline in the combat effectiveness of the armed forces. With the two or three states in western Sichuan that the Thunderbolt Army currently possesses, they simply cannot afford to fight a war of attrition. Although the production efficiency of the Thunderbolt army was far higher than that of the Sichuan and Western Mongolian army, in addition to industrial and mining products, whether it was population or food and other necessities of life, it was far inferior to the Sichuan Mongolian army, not to mention the huge Mongol Empire. The northern Han land controlled by Kublai Khan alone had a population and area more than 100 times that of the Thunderbolt army. Even if the casualty ratio of the two armies was 1 to 10, the Thunderbolt army could not afford to consume it.

Faced with the siege strategy, the Thunderbolts either sat back and fell into a situation of slow death, or waited for the Mongols to free up their hands to deliver a thunderous blow. And taking the initiative to attack the enemy's strong cities and fortresses is playing right into the enemy's hands. In fact, this is the essence of Liu Da'er and Cao Zhizhou's siege strategy. They knew that the strength of the Thunderbolts lay in the fortified cities equipped with artillery and the naval warships. As long as these two things are restrained, the Thunderbolts have nothing to fear. In the battle of Yokohara Fort, Liu Heima also made the same suggestion, but the self-esteemed secret fire could not listen to his opinion at all. On the contrary, although he looked down on the generals who were not of his own clan, he was also kind and agreed to the proposal of the two men.

To break the enemy's siege strategy, the waterway is relatively easy. It's just that even if he can take Meizhou City, Liu Daer can lead his army to retreat to the fortress far away from the river, and wait for the opportunity to send small boats to attack the merchant ships from the river and lake. Due to the high terrain of Jiading City, although the warships can bombard the city, they will also be hit by the condescending defense facilities, and they will inevitably suffer heavy losses. Even if they were lucky enough to take Sangui, Jiuding, and Lingyun City at the risk of heavy casualties, the new annexed army would retreat to the range of gunboat fire, and under the protection of the Mongolian army, they would wait for an opportunity to attack the Thunderbolt fleet. However, the Perak navy warships had to control the river from the Jinma River and the Nanhe River, and also prevent the Mongol navy from breaking through Pengshan City from Chengdu, so there were not too many ships to escort the merchant ships. Trading under frequent attacks would not only result in cargo damage and shipbuilding, but also a large number of casualties among caravanserais.

The main battle weapon of the Thunderbolt infantry is very heavy and heavy, although it has been lightweighted according to the needs of field battles, and it is equipped with mules and horses, but the marching speed is still slow, and it takes a long time to change from a marching state to a combat state. During this time, it was extremely vulnerable to surprise attacks by the Mongol cavalry. Although the Thunderbolt Army already has a cavalry brigade, it is far inferior to the Mongol cavalry in terms of riding skills and combat experience, and it is difficult to block the surprise attack of the same number of Mongol troops. At present, the Sichuan Ximeng army has 3,000 elite iron cavalry in the New Wing alone, and if you add the cavalry under the command of the secret Huoli and others, the number is several times that of the Thunderbolt army, which makes it extremely risky for the Thunderbolt army to attack Meizhou Jiading and Yazhou by land.

Even lightly armed units such as the Thunderbolts' Special Brigade approaching an enemy city or fort through a trail on a mountainside ridge will find themselves full of obstacles. In Liu Da'er and Cao Zhizhou's plan, a large number of criss-crossing trenches would be dug around the cities and fortresses of Mingshan, Meizhou, and Hongya, which the Perak army might attack. These trenches were used to slow down the Thunderbolts' advance and prevent the artillery from approaching the walls. The defenders of the city could also use these trenches to raid the Thunderbolt artillery positions. Since the rise of the Thunderbolt army, both the Mongolian army and the official army have been studying ways to deal with artillery, and they have invariably adopted the method of civil fortifications. Although the construction of civil fortifications is time-consuming and labor-intensive, the effect of preventing shelling, especially light artillery, is extremely significant. Of course, Liu Da'er and Cao Zhizhou's plan was not a passive defense, but something to rely on - they also had fortress cannons, and they were preparing to cast more. Although these replica cannons were far less powerful than the Thunderbolt fortress guns, they could be used against light artillery when mounted on the city walls.