In Yizhou City, the Zhou army successfully blocked the Liao army. It can be seen that the Liao army was very serious this time.

Guo Hao stood in the room at the top of the city, Li Hui and Wang Wei stood beside him, and occasionally arrows flew in, but they were stopped by the two of them.

It seems that his death did not have a great impact on the Zhou army. At least people temporarily forgot about him when they did not encounter a crisis.

This is not the time to show up. Guo Hao asked Zhao Kuangyin to guard the battlefield in the east. Once the Khitan showed signs of retreating, he would chase after them and entangle them.

Zhao Kuangyin accepted the order, and Guo Hao secretly left Yizhou with his men, heading west, and observed the guards of Yanyun's passes along the way.

The Sixteen Prefectures of Yanyun, also known as the Sixteen Prefectures of Youyun and Sixteen Prefectures of Youji, are ancient geographical terms, referring to the sixteen prefectures in northern China centered on Youzhou and Yunzhou, namely the later Beijing, northern Tianjin, northern Hebei, and northern Shanxi.

The sixteen prefectures of Yanyun specifically refer to: Youzhou, Shunzhou, Ruzhou, Tanzhou, Jizhou, Zhuozhou, Yingzhou, Yingzhou, Xinzhou, Guizhou, Wuzhou, Weizhou, Yingzhou, Huanzhou, Shuozhou, and Yunzhou.

The geographical location is very important. It is a place that military strategists must fight for in the past dynasties, and it is also a natural barrier for the Central Plains dynasty to protect agricultural areas and resist the invasion of nomadic peoples. It is also the base for the Central Plains dynasty to conquer the Northeast during its prosperous era.

For the Central Plains dynasty, the Sixteen Prefectures of Yanyun were its gateway to the north.

On the one hand, during the period of national prosperity, it was the stronghold and bridgehead for the Central Plains dynasty to control the northern nomadic peoples.

Emperor Yang of Sui built Linshuo Palace in Zhuo County as a palace. After seven years of Daye, he used troops to Goguryeo three times, using Zhuo County as a base to gather troops, military weapons and grain storage.

On the other hand, the Sixteen Prefectures of Yanyun were also the barrier and frontier for the Central Plains dynasty to resist the invasion of the northern nomadic peoples, and were the "strategic buffer zone" of military struggle.

The Great Wall and the Five Passes in the northern part of the Yanyun area form a strong and unscrupulous artificial line of defense.

In ancient wars, cavalry undoubtedly had absolute advantages over the Central Plains army with infantry as the main force, while in military geography, the Great Wall could play a defensive role in the southward transition of the northern nomadic cavalry.

Next to the Sixteen Prefectures of Yanyun on the south side of the Great Wall, with its solid city, towering and steep mountains and crisscrossing rivers, it forms another strategic line of defense.

It is a powerful support for the Great Wall's defense line and forms a relationship with the Great Wall that supports each other.

For the northern nomadic peoples, the Sixteen Prefectures of Yanyun are also strategically significant.

After occupying the Sixteen Prefectures of Yanyun, they completely changed their passive situation in the military struggle with the Central Plains dynasty.

Although the northern nomadic regimes have strong military power, they do not have advanced cultural systems and do not have fixed financial income.

Due to the limitations of its own regime system, in the process of fighting against the powerful Central Plains dynasty, they either achieved temporary military victory or were completely defeated by the powerful Central Plains dynasty.

However, after occupying the Sixteen Prefectures of Yanyun, this situation changed completely. Through the window of the Sixteen Prefectures of Yanyun, they began to understand the Central Plains, gradually came into contact with the Central Plains civilization, and learned the advanced production methods of the Central Plains.

The area under the jurisdiction of the Sixteen Prefectures of Yanyun is about 600 kilometers east-west and 200 kilometers north-south, with an area of ​​about 120,000 square kilometers.

The north of it is in the northern part of today's Hebei, at the northern end of the vast and flat North China Plain, encompassing the majestic and steep Yanshan Mountains; the west is in the northern part of today's Shanxi, which is mountainous and has a complex terrain.

The situation in the narrow and long area of ​​Yanyun Sixteen Prefectures was very dangerous, and it was indeed a military natural danger in ancient times.

The Yanshan Mountains and the Northern Taihang Mountains are lying across the northern part of the Yanyun area.

In ancient times, when productivity was low, transportation was backward, and military technology was underdeveloped, the mountains were an invincible natural danger in front of people.

Judging from the terrain of Yanyun, the Yanshan Mountains and the Northern Taihang Mountains are like two connected city walls standing in the north of the North China Plain. The intersection of the two mountains is more like a "city corner" that casts a sky-cast "city corner". The northern nomadic peoples with cavalry as the advantage are severely blocked here.

The majestic and steep mountains have built the first natural defense line in the Yanyun area strategically resisting the northern cavalry to move south.

The Sanggan River and Juma River flow in the central and southern part of the Yanyun area, which are rivers at the center of strategic defense.

In ancient China, rivers, swamps, especially rivers, often became defensive barriers to resist the enemy.

In fact, in the era of cold weapons with swords, guns, bows and arrows as their main weapons, using river defense is a common method to defend against enemies.

In addition, rivers can also transport military strategic materials.

The Juma River uses Yishui and Baigou River as its two wings to form the river defense system in the southern part of the Yanyun area.

The crisscrossing rivers obviously built the natural second line of defense in the Yanyun area strategically resisting the northern cavalry to move south.

The strict defense system in Yanyun area not only includes natural barriers but also human defense lines, that is, the Great Wall and the Five Passes.

The Great Wall was built since the Qin Dynasty and was a great defense project in ancient China. It played a huge national defense function during a long historical period.

At the same time, the Great Wall is also the dividing line between two major forms of civilization, farming and nomadism, and plays a historical role in protecting advanced farming civilizations so that it will not be destroyed by the endless attacks of nomads.

Especially the Great Wall in Yanyun area played a huge role in preventing the northern cavalry from invading the Central Plains dynasty.

In addition, the role of the "five passes" in this region in strategic defense cannot be underestimated. Between Youping, the five passes are used as the form of victory.

These five passes are: Jinpo Pass, Juyong Pass, Gubeikou, Songting Pass and Yu Pass.

The majestic and dangerous Great Wall and the five passes form the indestructible artificial defense line in the Yanyun area strategically resisting the northern cavalry to the south.

With such a special terrain and an important position, even if the emperor of the Liao Kingdom does not pay attention to it, it is not so easy to take back Yan Yun.

...

When Guo Hao entered the city in Daizhou, he found that the people in the city were very excited because the army of the imperial court was right in front of Yanmen Pass, and had lost the lost land for decades and was finally recovered.

The people's hearts are available, Guo Hao couldn't help but nodded, walked into a tavern, listened to the people's comments, and everyone was still very confident in the court.

"Hmph, a group of ignorant people."

At this moment, a strong man caught Guo Hao's attention and saw him sitting there alone with only wine on the table. Guo Hao whispered to Li Hui, and Li Hui immediately stood up to find the waiter.

The kung fu was not very good, so the waiter served wine and food, but not Guo Hao, but to the strong man. The strong man was stunned and said, "What are you doing? I just have a bowl of wine."

"This guest official, this is what the young one also asked you."

Following the direction of the servant's finger, the strong man saw Guo Hao laughing at him. The strong man saw Guo Hao wearing a mysterious suit and secretly majestic, and he saw that he was not an ordinary person at first sight.

"Why are you giving me food and drinks? You can't accept this without any merits? Yang cannot ask for this!"

Guo Hao smiled slightly when he heard this and said, "I just heard from this gentleman, who seemed to have some doubts about our army's arrangements. I happened to be in the army, so I don't know what kind of arguments my kindman has."

When the strong man heard Guo Hao serving in the army, he knew that his sarcasm had been heard by others just now, but he didn't feel embarrassed.

"Gao Ren dared not be accused of it. The imperial court took advantage of the large army's attack on Yizhou and sent troops to attack Shuozhou. This idea is very good.

However, the Yanyun area spans hundreds of miles, and even if it is fought, it may not be easy to defend. After the Liao army reacts, it will definitely fight back with all its might. At that time, our army's front line will be too long, and the supply of troops will probably be a problem."

After the strong man finished speaking, Guo Hao looked at him in surprise, because what he said had always been a question that Guo Hao was thinking about.

But he didn't dare to wait any longer. After coming to the northern border, he realized that this time the Liao army went south was arranged by Xiao Siwen. Xiao Siwen may not be very famous, but his daughter is different. She is the famous Empress Xiao in history!

Therefore, although the follow-up matters have not been decided yet, the army has arrived at this time and the arrow is on the string and has to be fired. As for the follow-up matters, we will talk about it after the fight is over.

"A kind-hearted brother is very opinionated, and I am impressed. I wonder if a kind-hearted brother has a way to break the precepts?"

Guo Hao looked at the strong man with anticipation. The strong man was real, shook his head and said two words: "No!"

Guo Hao was stunned when he heard this and shook his head: "This is enough. I'll give the wine and food to my brother. I think my brother is also a martial arts practitioner. I wonder if he can tell his name. If a brother intends to join the army in the future, he may be able to meet again."
Chapter completed!