Zheng Huchen's worries Zhao Yu also considered it, but he thought it was a matter of pros and cons. Based on what he knew in his previous life, and the experience of fighting the enemy in the past ten years, 'urging' the Mongol army to build a castle system was a matter of more advantages than disadvantages.

The myth created by the Mongols that they were able to sweep the world and be invincible has been studied by later generations, and some people think that it is a combination of various conditions such as the hard-working Mongolian horse, the application of Takahashi's saddle, the great power of the bow and arrow, and the need for logistical supplies and the possession of multiple auxiliary horses. However, Zhao Yu thought that the reason why the Mongol army was able to achieve such a record was that the external conditions, good weapons and heroic fighting character were indispensable, but it was not necessary.

Because at the same time, the regional countries conquered by the Mongols had more advanced weapons, excellent war horses and large populations, but they were still defeated, so Zhao Yu thought that the good strategy and tactics of the Mongols were the foundation of their victory. You must know that at that time, all the Mongol tribes had a combined population of only one million people, and could provide up to 150,000 Mongolian cavalry, how could they complete the cause of conquering the world?

The Mongols were the "people on horseback", the best nomadic people, the Mongols were much better at riding than their enemies, and the fact that Mongolian horses were usually grazed in harsh conditions meant that they were not very tall. However, it is also a fact that Mongolian horses are very hard-working and adaptable. Zhao Yu once experimented, at this time, any Mongolian war horse can ride more than 300 miles in a day without long-term rest, which is stronger than the index of modern Mongolian horses, which may be caused by the degradation of the breed in the later period.

In addition, the Mongol army in the early days had only a single cavalry, which allowed them to avoid the problem of coordinating the use of mobile arms with infantry, a problem that still plagues the armies of various countries. The combination of these factors, combined with the abundance of spare horses, gave the Mongol army a mobility that would seem terrible even today, allowing it to conduct rapid maneuver operations over a vast area, and to be able to assemble an army for concentrated use in a very short period of time, overcoming the problem of lack of troops.

This high-speed mobility allowed the Mongols to implement a strategy of separate and combined attacks. They dispersed their armies into several scattered columns, threatening several important targets of the enemy at once. In this way, the enemy has to divide his forces to defend several targets and disperse his forces, or concentrate his forces to protect some targets and have to abandon others; If the enemy dispersed his forces, the scattered Mongol columns would suddenly assemble and launch an offensive with superior forces; If the enemy did not disperse their forces, the Mongols could easily seize many strategic points and make the tide of battle more and more favorable to them.

In addition, in Zhao's opinion, the most favorite tactic used by the Mongols was the so-called 'mangu', the core of this tactic was to pretend to flee and induce the enemy to pursue, and its essence was speed and suddenness. The Mangugu, on the other hand, is a specially selected force that attacks the enemy alone, rushes quickly in front of the enemy ranks, fires arrows at the enemy from all directions like a storm, and then flees immediately, never engaging in close combat with the enemy's infantry who are in full position, similar to modern tactics of fire harassment.

Combining the speed of their horses with skillful control and timing, the Mangus successfully attacked the enemy with a fierce attack that inflicted considerable losses on them, and then retreated in a desperate panic by feigning panic. At this moment, only the most astute generals and opponents with strict military discipline could restrain the urge to pursue the Mongols, who were feigning defeat. If they don't succeed, they will repeat this tactic until they provoke the enemy.

Once the opponent followed the pursuit, the Mongol army would first lure the enemy cavalry out of the protective range of the support, and was often annihilated by the ambush after losing the tight formation protection. At this time, the Mongol archers would suddenly attack the opponents who had entered the ambush circle, annihilating the scattered enemies one by one and causing great confusion to the enemies who could still maintain the formation, leaving the enemy in confusion and heavy casualties with little resistance to the Mongol heavy cavalry who were waiting for them.

In this way, with a strong castle as the backing, and cavalry coming and going like the wind as a mobile force to help, it seems that it can really form an impregnable defense line to block the Song army south of the Yangtze River. However, Zhao Yu was not overly worried, he thought that the numerous cities made it difficult for the Mongol army's best mobile tactics to be brought into play, and would instead give him an opportunity.

First of all, after years of conquest, in order to adapt to the changes in the war situation, the Mongol army is no longer a simple cavalry, but has formed an army with the coexistence of combined arms such as naval army, infantry army, artillery army, cavalry army, and craftsman army, and its mobility ability has been greatly reduced; In addition, the Mongolian army is currently a wartime soldier, and it is stationed in various places in the form of tuntian on weekdays, and once something happens, it must be grouped in a centralized manner before it can be put into battle, and the reaction time must be extended accordingly.

In addition, the Mongolian army is fighting on its own soil, and it cannot go anywhere to grab logistics supplies as before, which also limits their range of mobility, making it difficult for them to carry out large-scale roundabout operations, and the usual tactics are also difficult to play, after all, every step they take will cause them economic losses. Therefore, their tactics will be similar to those of the Song army in the northwest against the Western Xia, the enemy army will retreat into the fortress to protect itself, and then ask for help from the surrounding garrisons, and then counterattack after the arrival of the army.

In addition, the dense water network in the Lianghuai region and the limited mobility capability are still a hurdle that the Mongolian army cannot bypass; once the main road of marching is cut off, it will be difficult to carry out rapid mobility, and there will be zero strategies and tactics, and it can only rely on the city to defend it. Luckily, I was able to hold out until reinforcements arrived; Bad luck, I can only wait for the friendly army to come and collect the corpse. Therefore, it is difficult for the enemy to build a city to change the reality that they have lost the advantage of rapid mobile warfare, and it cannot fundamentally reverse the passive situation.

In fact, although we can often see some famous siege battles in wars, often the besieging side often has to pay a huge price, and it takes a fortified city after brutal siege battles, and many siege battles cannot be won even if they sacrifice greatly, resulting in defeat. But Zhao Yu found that in fact, there was no need to fight for each city step by step in the war, and most of the cities did not have to be fought and bypassed.

The art of war pays attention to the right fit and wins by wonder. In the battle to recover Jiangnan, although Zhao Yu also carried out several siege battles, the intensity was not as fierce as the peripheral battles, and the siege battles were all aimed at capturing central cities or strategic places such as Lin'an, Jiankang and Ezhou. Of course, this is also related to the Mongolian army's large-scale demolition of the city, so that he has no city to attack, but this is also one of the reasons why the living force of the Mongolian army was annihilated and Jiangnan was quickly recovered. However, Zhao Yu also knows that no matter how the battle is fought, several types of cities cannot be avoided:

The first is a politically centric city. Most of these cities are capitals and sub-capitals, such as Chang'an, Luoyang, Jiankang, Kaifeng, Beijing, etc. In any case, in order to achieve a complete victory in the war, the capital must be captured. And such cities are under attack, or the war has come to an end, or the enemy army has a long-range attack to take a decapitation action, and of course, the meaning of attacking the capital is not immutable, only for the sake of destroying the country.

In the Jingkang period, the Jurchens for the first time came to the city of Bianliang was like this, they faced resolute resistance and did not capture the city, but extorted countless property, and signed an alliance with the Northern Song Dynasty under the city, and the greatest significance is to find out the combat effectiveness of the Song army, so that they made up their minds to destroy the Song Dynasty, and when they came again, they captured the city, took away the second emperor, and destroyed the Northern Song Dynasty regime.

Another similar battle known to Zhao was also carried out by the Jurchens, who led an army to attack Beijing at the end of the Ming Dynasty. In his opinion, the military strength of the Eight Banners at that time was not strong enough to directly attack Beijing, but it was more economical and cost-effective to cross the border wall to attack Jifu Shandong, but Huang Taiji still organized a surprise attack on Beijing regardless of the risk of being cut off by the Ming army on the Ningjin line. But the result of this operation was that Emperor Chongzhen of the Ming Dynasty killed Yuan Chonghuan, the old opponent of the Qing army, so that "no one will benefit from the side affairs, and the Ming Dynasty will be decided".

Another example is that although Luoyang during the Sui and Tang dynasties of the Northern and Southern Dynasties has not always been the capital, it has always been a battleground for soldiers because of its very important traditional political status. The Western Wei and Northern Zhou Dynasty organized five tragic attacks on Luoyang, and only one was successful; The rebellion of Sui Yang Xuangan, the Wagang army Li Mi attacked Wang Shichong, Tang Taizong besieged Wang Shichong, and the rebels of the Anshi Rebellion went south, all of which attacked Luoyang.

Although Luoyang is only the vice-capital, first, Luoyang occupies the geographical advantage of controlling the Central Plains nearby, and second, with the eastward shift of the economic center, Luoyang's political status is gradually equal to Chang'an. Therefore, Luoyang's gains and losses largely determine the quality of the situation in the Central Plains, so Luoyang quickly became the focus of the attack during the war.

Then there is the battle command center type city. Limited by the poor conditions of communication and transportation in ancient times, the central government's control of the vast territory mainly relied on the administrative centers of each locality. In the event of the outbreak of war, these administrative centers were also immediately transformed into regional operational command centers. Such cities are represented by Taiyuan, Hejian, Zhongshan, Jinan, Shouyang, Jingzhou, etc., and Zhao Hao has always coveted Shouzhou for this reason.

Therefore, although most of these cities are located in plains with flat terrain and developed transportation, and it is easy to bypass them without fighting, the attacking side will not let go easily for the purpose of destroying the enemy's command center, and even if the city defense facilities are extremely strong, they must take them down at any cost. During the Northern Dynasties, the Northern Wei Dynasty attacked the Middle Mountain of Houyan, the Western Wei Dynasty destroyed the Liang Dynasty and first attacked Jingzhou Jiangling, the Northern Zhou Dynasty Yang Zhong attacked the Northern Qi Jinyang, the Jin army besieged the three towns of Taiyuan, Hejian and Zhongshan, and the Ming Zhu Di Jingjing Battle besieged Dezhou and Jinan, all of which were based on this reason.

But the situation is not static, and when higher-value targets emerge, such cities are quickly abandoned. In the Battle of Jingyan, Tie Xuan insisted on Jinan, and Zhu Di repeatedly attacked and could not resist. Later, after being reminded, he found that the offensive method of one city and one place could not win, so he changed his strategy, abandoned Dezhou, Jinan and other big cities, and went south along the canal to take Nanjing, defeating Emperor Jianwen with the strategy of capturing thieves and capturing the king, and then turned around to solve the Jinan problem. This is a strategy that must be adopted in order to change the situation of a strategic campaign, but the value of Jinan itself as a regional command center remains unchanged.

The other is a traffic channel city. The so-called traffic channels are roughly divided into two categories, one is the traffic channels on the land, and the other is the traffic points on the waterways. Just like a Xiangyang city, Meng Yuan returned several times, allowing the Great Song Dynasty to survive for decades.

However, the traffic roads that a city can control are very limited, at most dozens of miles. Even if the surrounding road is difficult to walk, can't you avoid it completely? From Zhao Hao's point of view, sometimes it really doesn't work.

In this era of lack of means of transport, the army carried out conquests, especially the Central Plains army, which was mainly based on the infantry army, mainly relying on soldiers to march on foot, and the long-distance journey had a great impact on the physical strength of the soldiers. What's even more terrifying is that long-distance transfer will greatly consume logistics materials. The combat effectiveness of a unit is often tied to logistical support and the physical strength of its soldiers. To avoid the fortified city on the hole road would mean taking a long detour, which would inevitably greatly damage the combat effectiveness of the troops.

At the same time, the defender occupies a favorable position, which can not only follow the pursuit, but also defend the danger, which will cause great damage to the guest army. Therefore, the strategy for dealing with this kind of fortified city is to choose another direction of attack before the war starts, if you don't want to fight. And once the battle is engaged, it will either be captured or retreated.

Therefore, in order to solve the problem of traffic channels in the long run, it is necessary to completely take this kind of city and take it for himself, just as Zhao Yu did not hesitate to personally conquer Ezhou, and took this key point of controlling the entrance of the Yangtze River and the Han River, and the same as the current deployment of heavy troops to guard the main crossings along the river, because in the long run, the price they paid is completely insignificant compared to the later strategic benefits.

In addition, the 'gateway' type cities must be attacked. From the perspective of military geography, due to the blockage and division of mountains and rivers, China is roughly divided into strategic blocks such as the Central Plains, Guanzhong, Hebei, Hedong, Hanzhong, Shuzhong, Lianghuai, Jiangdong, Jingxiang, Liaodong, and Longyou. Some strategic blocks thus possess one or two obscuring cities.

This kind of city, either located at the mouth of the mountain or located in the key point of the river, is surrounded by dangerous roads on the left and right, and is controlled by a city on the left and right, like a shield, providing a strong screen for the large area behind. And what we often call "portal" is what it means. At present, Zhao Yu's intention to disrupt Meng Yuan by spreading rumors is actually related to the attack on Chongqing, the gateway to Sichuan and Shu......