Yan Yu had some courage in his work. Shortly after appointing Xianyu as the army to join his staff, Yan Yu issued an order to recruit some lieutenants and Sima stationed on the periphery of Hanzhong to return to Nanzheng.

These lieutenants and Sima were previously stationed in Xi'an, Jianwei, Wuwei, Shimen, Wucheng, Jianchang, Linyuan and other places respectively. In Jiang Wei's plan to gather troops and gather valleys, these troops were not idle positions, but were responsible for the heavy responsibility of guerrillas.

Once the Wei army launched an attack on Hanzhong, they would first attack Seoul, Lecheng and Yangping Pass, which were heavily defended by the Shu army. The task of these guerrilla troops was to detour behind enemy lines, cut off and destroy the Wei army's food route, and harasse the Wei army, making the Wei army exhausted to support the battle on the front battlefield.

Although these troops are not many and are extremely scattered, it seems that they will not play any role in the entire Hanzhong battle situation, but in fact, in Jiang Wei's conception, these guerrilla troops will play a very important role, and can even influence the success or failure of the Hanzhong battle.

It is precisely because these troops are small and scattered, with extremely strong mobility, and they are very familiar with the terrain in Hanzhong. Hanzhong is mountainous and complex, so as long as these troops hide in the valley, break into pieces, and fight on their own, even if the Wei army dispatches tens of thousands of troops, they may not be able to wipe them out.

When the Wei army attacked Hanzhong, the primary target of attack was definitely a fortress like Yangping Pass in Lecheng, Seoul. Those scattered guerrilla troops could only be considered as small flies at most. The Wei army would definitely send troops to encircle and suppress, but they would only send small groups of troops out. It is impossible to use the main force to encircle and suppress. In this way, these guerrilla troops still have room for survival.

The main function of these guerrilla troops is to move behind enemy lines. After the Wei army marched into Hanzhong, they will leave a long supply line behind them, and these supply lines basically travel through the high mountains and ridges of the Qinling Mountains.

The difficult road would inevitably face great difficulties in the logistics supply of the Wei army. When Zhuge Liang went to Qishan six times, the first issue to consider was the supply issue. The Shu army did not lack food and grass, but how to cross mountains and ridges to transport food and grass to Guanlong was the biggest problem. Even Zhuge Liang racked his brains to invent the wooden ox and flowed horses, which could not completely solve the problem of food shortage on the front line.

If the Wei army wanted to attack Shu, they would also face the same difficulties as the Shu army back then. The more troops they entered Hanzhong, the greater the difficulties would be. If this problem could not be solved, then the Wei army would eventually face the same situation of ending in failure.

The reason why Jiang Wei chose to gather troops and gather valleys was actually learned this trick from Sima Yi of Wei. Jiang Wei sent troops to attack Wei all the time. The most troublesome thing was that the Wei army could not hold on. Such a protracted war could not be defeated. Jiang Wei could not afford to fight in such a long-term battle. Jiang Wei could only ask for a quick battle. When most of the Wei army was in large numbers, they would station troops in the fortress. Using the Turtle Breath technique that Sima Yi had always used, dragging the Shu army to exhaustion, and finally retreated with regret.

If the Wei army can fight like this, why can't the Shu army?

Therefore, when Jiang Wei formulated the Hanzhong defense plan, he copied Sima Yi's tactics. Sima Yi never saw him garrisoning heavy troops in Qishan, Sanguan, and the front line of the Qinling Mountains, but placed his main force in Tianshui, Chencang, Chang'an and other relatively backward positions.

Every Northern Expedition of the Shu army basically did not encounter strong resistance after coming out in the early stage, and the progress was very smooth. However, once a confrontation with the Wei army, the attack was often weak. After all, with the Shu army's ability to attack, it was quite difficult to take down the defense centers such as Tianshui and Chencang. The war was delayed for a long time, and the Shu army could only be forced to retreat because of the food exhaustion. All attacks were almost a result of a slash of attacks.

The main reason why Sima Yi did not use the fighting style of defending the enemy outside the national gate and moved the defense line of Wei to the Qinling Line was that although these passes were dangerous, the road was difficult to move. If you station a large number of troops, logistics supply would be a big problem. What's more, Sima Yi had predicted when the Shu army would attack on the spot. If he had been stationed for a long time, it would only cause the Wei army to be trapped and his combat effectiveness would be reduced.

The troops were stationed on the Tianshui, Chencang and Chang'an lines. These places were both fortress cities and adjacent to the Wei River. The transportation of food, grass and materials was very convenient, and there was no pressure to stay for a long time. Therefore, Sima Yi took the initiative to deploy troops on the second line, rather than directly deploying troops on the Qinling line.

Now that the Shu army gave up the attack, the entire northern front of Shu will also change from attack to defense, entering the strategic defense stage. Some people proposed to garrison troops and horses in Xingshi, Jin, Baozhong, etc., and defend the enemy outside the national gate.

Of course, this is also a mature defense plan. When Cao Shuang attacked Shu, the general of the Shu army, Wang Ping, used this method to successfully block the Wei army's attack.

But times change. Now the Shu army is facing the pressure of fighting on two fronts, surrounded by enemies, and at the same time, it is naturally difficult to fight the Wei army. If such a strong defensive tactic is adopted, the Shu army will inevitably need to invest more troops and material resources. Now the military strength in Hanzhong is obviously not enough to maintain such a tactic.

Therefore, the plan to gather troops and gather valleys was almost a forced choice for Jiang Wei.

Since Sima Yi and later Guo Huai were able to successfully block the attack of the Shu army repeatedly, Jiang Wei had no reason to think that he could not use his own way to cure others, so that the Wei army could also taste the lack of food and grass to succeed.

The most important thing in the entire Hanzhong defense system is the defense of the three major fortresses, Lecheng Yangping Pass in Seoul. As long as these three city passes can be protected, the Wei army will be trapped in Hanzhong and advance and retreat.

These guerrilla troops will also play the greatest role. They are mobile and flexible, and can completely attack the Wei army's food routes and scattered military camps. If you shoot an arrow and change another place, the Wei army will have no chance to encircle them.

The existence of these guerrilla troops is a huge threat to the Wei army's logistics supply line. In order to protect the safety of the food route, the Wei army could only send a large number of troops to escort the food and grass. This undoubtedly puts the Wei army on a heavier burden, and logistics transportation has made it worse.

If the Shu army guerrillas could successfully destroy the Wei army's grain transport team several times, it would have a fatal blow to the already severe logistics transportation of the Wei army.
Chapter completed!