No matter how the subsequent battles are to be fought, the idea of ​​"keep confidentiality in the first stage, split the troops and advance fully, and conduct full investigation" is always correct.

So after discussing with Li Su, the next day, Liu Bei's army began to go south in batches one after another, exploring the way while consolidating the transit stronghold and transporting and hoarding grain.

It was the 29th day of the first lunar month when Huangfu Song and his team divided the troops. The 30th day of the first lunar month left Sanguan. It took three days before the dragon raised his head on the second day of the second lunar month before he could barely cross the main ridge of the Qinling Mountains.

The day when the dragon raises its head is about a few days after the Jingzhe period, so when the army crossed the main ridge of the Qinling Mountains, the snow in the valley had almost melted, and the peak next to it was still not yet melted.

The valley is already very muddy, and you can often see sections flowing down in a trickle. From outside Sanguan to the southwest and to Donglang Valley, the terrain gradually becomes higher, so these snow-melting water flows will flow towards Chencang City.

Li Su rode on horseback most of the way and enjoyed the highest civil servant treatment, but when he encountered a dangerous place where it was muddy and unstable, he had to dismount and be supported by the warrior.

When they reached Donglang Valley, the army temporarily rested. Liu Bei found Li Su, and had some dry food, wine and chatted with him.

Liu Bei personally broke a piece of donkey meat and cooked it to him, and sighed: "We have been in Shuofang for a long time. The difficulty of this Shu road has only been very eye-opening today. No wonder Zhang Luneng intercepted the Han envoy. Walking the Chencang Road is already so muddy. If you walk on the Baoxi Road in Mei County or even go straight to the Ziwu Road in Chang'an, you don't know how dangerous it is."

Li Su took a sip of water before taking the fire: "It's just muddy, but it's good to solve it. It's good that the melting water will flow. It's because of this that the muddy snow has just melted, and our army's advance is sudden. Zhang Lu is prone to be unaware of it. This is worth consuming."

Liu Bei threw a small stone into the mountain stream, shook his head and sighed, "If you don't be wary, there will be no patrol guards in Yangping. Let's secretly climb the wall, right? As long as we start to attack the key points, we can't take it for a moment, and the enemy reinforcements are still coming."

Li Su didn't want to say depressed words, so he wanted to find a wrong topic. He looked at the splashes of water splashed by Liu Bei in the mountain stream, and his heart moved and asked:

"Can there be local business travelers and medicinal farmers who are detained to the north today? I was just looking for local people who are familiar with geography to ask. Can the melting water of the snow in the mountains really flow under the city of Chencang? When we set out from Chencang, there was no river flowing out of the Qinling Mountains."

Liu Bei thought Li Su was changing the topic and disdained to comment: "Is this very important?"

Li Suwei shrugged: "Sunzi said, "Those who are afraid of the unexpected will win, and those who are generals know more about geography. I read history and are always curious about how the Marquis of Huaiyin helped Emperor Gaozu secretly visit Chencang and asked the local geography of the natives. Maybe it would be inspiring."

Liu Bei sneered softly without any malicious intentions: "Then think about it slowly. So what if you know this kind of thing? You can't go back hundreds of years ago and help Emperor Gaozu beat him better."

Fortunately, Liu Bei is a real normal person and doesn't know the concept of "time travel". Otherwise, he should have said, "You can't travel back to help Emperor Gaozu."

Li Su quickly found an old local herb harvester who was detained by the army, politely divided the other party a piece of donkey meat and asked about the river.

The old farmer replied in detail: "General, this stream can indeed flow all the way to the city of Chencang. When the water is the highest, it can also flow into the moat south of Chencang City at about the end of February, and finally enter the Wei River! I have been collecting herbs here for a long time and often go to Chencang to sell goods, so I know that. But this river does not often exist, and it only starts in spring and melts snow for one or two months. The year with the most rainfall will not exceed three months, and it will be dry at the rest of the time."

Li Su's heart moved: Could it be that when Han Xin secretly visited Chen Cang, he used water transportation? So logistics was easy to solve? But why did Zhuge Liang only go to the Qishan Road in Wudu County during the Northern Expedition, but he could not break Chen Cang?

Is Hao Zhao's city too strong, or is Zhuge Liang's logistics too weak to continuously transport grain to Chencang front line to maintain the siege of Chencang? If it is too difficult to continuously transport grain to siege of Chencang, is it because Zhuge Liang did not use water transportation? Or is the season he chose to send troops differently from Han Xin, which led to not the water season?

This series of questions made Li Suru, who had always taken three or five steps, skulled in his throat. He wanted to explain his doubts, so he sincerely asked: "When the water volume of this river is the largest, how deep can it be? Can you take a boat?"

The old medicine farmer shook his head: "It was only four or five feet deep at the deepest time, and the strange rocks were messy. How can I walk on the boat?"

Li Su touched her chin and thought to herself: It seems that it is not a matter of season. This stream cannot ship grain no matter what the water level in the season.

Forget it, think of this step first, make a record, and if Zhang Lu is leveled in the future, come back and slowly investigate the terrain if you have time.

Zhuge Jin, who always followed Li Su, couldn't help but wonder when he saw this: "Why is Zhonglang focusing on these useless things? You might as well talk about it, maybe his subordinates can help investigate."

Li Su said casually: "I just want to know if the stream in Chencang Valley has always been so shallow. If you have time in the future, you can ask the soldiers to dig out the gentle slopes on both sides of the river, dig out the trees and soil, and look at the rock formations of the mountain walls."

Li Su studied diplomacy in his previous life and his geography scores were still very good. First of all, although geography is considered a science subject from a scientific perspective, he was assigned to liberal arts when he was the subject of the college entrance examination, so he also had to memorize more things.

Secondly, learning diplomacy requires a very deep understanding of various international rivers and to know the situation "since ancient times". So Li Su traveled for two years and is still aware of the historical trajectory of the Yarlung Zangbo River, the Ivalody River, the Nujiang River, and the Lancang River (Mekong River). Where can he flow through foreign countries and enter the sea.

Because when diplomats use all the skills of "taking advantage of loopholes in international treaties to repair water conservancy projects in the upstream", threaten downstream neighbors within the framework of international law, and force them to make concessions and accept diplomatic blackmail.

Relying on this course, Li Su also understood some experience in geography exploration in water conservancy. As long as he digs out the soil next to the riverbed, he can see whether it is sedimentary rock, shale, or basalt, or granite.

If it is the former, it means that the valley bottom is so deep. Historically, it was eroded by water flow. There was a river but now there is no river. If it is the latter, it means that there has been no river here since ancient times. It is completely crustal movement that accumulates on both sides to form peaks, and this place is naturally a low point.

Zhuge Jin did not know the geographical knowledge, so he just silently recorded what Li Su must know, preparing to go back and read the classics, supervise the soldiers to dig the ground, and help the generals do these small things within their ability.

...

Exploring the road along the way in Donglang Valley and geographical surveying, the army finally crossed the highest point of the Qinling Valley Road in this area on the third day of the second month, and then began to go downhill and arrived in Hechi County on the fifth day of the second day.

This is a small river valley plain with a radius of dozens of miles. You can rest for a while. The Western Han River is more than ten miles south of the county town.

After arriving here, Guan Yu temporarily served as a guide and led two thousand troops to lead the way to lead Yu Fuluo, heading straight westward along the river valley to the upper reaches of the Western Han River.

Eighty miles west of Hechi is Xiabian, and eighty miles west of Xiabian is Wudu. The north of Wudu is Qishan Avenue, and you can reach Ji County, the capital of Tianshui County.

Li Su also personally surveyed the surrounding area before he gained a real understanding: in history, Ji Han's army wanted to go north from Hanzhong, as long as he did not go to Ziwu Valley but to go northwest, then there was no fork between Yangping Pass and Hechi, and there was only one road.

It will only break after arriving in Hechi. Guan Yu escorted Yu Fuluo to Dazhong to raise horses and farming, which is the easiest way to go, that is, Zhuge Liang often goes out to Qishan. The other is where Liu Bei and Li Su came this time.

Yu Fuluo's movements were equivalent to "going from Chen Cang to the south into the Qinling Mountains, then going to Wudu and then going north again". This posture is also strategically deceptive because it can be disguised as

"Huangfu Song led the main force of the Han army to pursue Han Sui in the Weishui Valley of Longshan, but Han Sui retreated slowly because of the blockade of the valley and was defeated but not in chaos, which led to Huangfu Song having no space to detour and spread his troops and encircle Han Sui's retreat." Therefore, "Liu Bei was invited to send out a surprise troops, go to the Qinling Mountains and bypass Longshan, and then appear behind Han Sui in the Weishui Valley of Longshan from the back."

This logic is a bit confusing, but if you deceive him like this, he will at least understand it.

Because of this, during the journey, Liu Bei's army captured the business and pesticides and the hunters temporarily seized them, and they all told them with confidence, "Our army took this route to sneak attack Han Sui's back, and the purpose was to circle the Qishan Road to Tianshui."

In this way, if these people have Zhang Lu's detailed work in public and escape, Zhang Lu will not be immediately alert.

Li Su is so stupid that even prisoners who don’t intend to let go must be deceived, and the fraud must be done in a complete set of tricks.

This is what acting skills are!

The next day after Yu Fuluo was divided into troops to play westward, on the sixth day of the second month, Li Su also brought hundreds of elite scouts, under the cover of Zhao Yun, to quietly go south to survey the terrain outside Yangping Pass.

Liu Bei also wanted to grasp the information of the battle situation and insisted on visiting him lightly and simply. He had to bring a few more powerful generals to protect him, and all of them disguised as caravans.

As he headed south, Li Su did not travel around in vain, but kept his vigilance and observation records. He made detailed records of how many roads he had walked every day and how far he would have to attack in the future.

As for the way to measure the route, he asked the soldiers to count the actual steps, each of them counted 5,000 steps, then replaced them and rested, and finally summarized them. In this way, the disadvantages of not being able to see the actual route can also be solved by looking at the map.

This careful and cautious attitude towards measuring the journey made Liu Bei, Lu Su and other military escorts amazed, and secretly praised Li Zhonglang for his pre-war staff work as a too detailed person.

"The straight line from Hechi to Wuxing is about 70 miles, but along the way, you have to zigzag along the Western Han River Valley. The actual journey is 110 miles. It turns out that you can't see the straight line distance on the mountain road.

The straight line from Wuxing to Juxian was thirty miles, the mountain road was actually fifty miles, and Juxian was fifteen miles along Mianshui to Yangping Pass, which was actually fifteen miles. This section of the river was very straight. Our army half-riding horse and half-leading horses, and walked in light clothes for two days."

When the last ten miles were left before Yangping Pass, the road exploration work was finally completed. Li Su and Liu Bei quietly climbed up the hillside to look at Yangping Pass, and checked the mileage road.

If you have to launch a sudden attack on Yangping Pass in the future, it seems that it is too late to start from Hechi. Unless you walk one night and arrive at Wuxing, take a rest, and then cross the mountains from Wuxing to Ju County at dawn. If you walk seventy miles during the day, you will still be within the limit of the mountain road marching.

This time, because Zhang Fei was still recovering from his injuries, he did not come with him. There were fewer reckless people around Li Su who questioned him.

In the end, Dian Wei, who had only one person guard, was a little impatient: "Zhonglang, if you want me to say, what are these things, just lead troops to attack Yangping Pass and try it?"

Li Su scolded: "Nonsense! We have worked hard to make this sudden attack. Zhang Lu must not be alert until the moment of the investigation. Yangping Pass is dangerous and narrow. Once it is exposed, it is possible that it will not be able to attack for several years!"

Li Su knew the lessons of history too well, and he didn't have to read the Romance of the Three Kingdoms. Just look at the Romance of the Romance, you will know that in history, the northern regime concentrated all its efforts to attack Yangping Pass, and no formation battle between Ming chariots and Ming horses had ever been defeated.

The only two records of breakthrough were Cao Cao's conquest of Zhang Lu and later Zhong Deng's conquering Shu Han.

When Cao Cao conquered Zhang Lu, he relied on building troops at the beginning. After fighting for more than 100,000 troops for so long, he was useless. In the end, Zhang Lu's younger brother Zhang Wei was thrust out of the brain and took the initiative to go out of the barrier to fight back. As a result, Xiahou Yuan was ecstatically chased and chased him through the barrier.

When Zhong Hui entered Hanzhong, he relied on the fact that traitors surrendered, and Jiang Wei was blocked by Deng Ai from the road back to Hanzhong, so the morale of the Yangping Pass was extremely low.

In other words, the two attacks in history were only broken by "scamating out the main forces of the enemy's defense, or being isolated from the outside and not returning to the gate to defend."

As for the routine of "imitating Deng Ai Zhong to attack from Longyou and Guanzhong", I don't even think about it now, and it doesn't fit the actual situation at all. The premise of that move is that Jiang Wei was originally outside the pass and could be isolated and restrained by you. Now Zhang Wei is like a turtle, and the whole army is hiding, so what should we divide it?

If Li Su wants to think about a plan, his thinking inertia will definitely be "how to trick the main force of the enemy's guarding troops out and eliminate them", and then attack them again.

"Yangping Pass is so majestic and dangerous. The reason why I always advance secretly is to see if there is a way to catch a chance to attack by the main force of the enemy. Either the main force of the guard pass switches to Hanzhong, or the main force of the guard pass suddenly was deceived out of the pass by our army using the excuse of being confused, and then suddenly came out. If this was not the case, this battle would not be easy."

Li Su observed the terrain repeatedly and discussed with Liu Bei and Lu Su.

When Zhang Wei met Xiahou Yuan, he was foolish and took the initiative to attack. It was once a century.

Li Su could not place his expectations on the enemy's repeated attacks on the once-in-a-century shark arm, he could only take the initiative to facilitate it.

"Even if there is no large army of imperial court nearby, even if it is kept confidential, Zhang Wei would not be so stupid as to leave the customs, right?" After hearing this, Lu Su, who was beside him, thought again and again and again, he really couldn't imagine how the enemy could be so mentally retarded.

"Can you expect Zhang Lu to force Zhang Wei out of the seclusion after the battle begins?" After Li Su was poured cold water on Lu Su, he couldn't help but seek the second best fantasy in his heart. He hoped that Zhang Lu would be mentally retarded and misjudged the situation like Li Longji, and force Zhang Wei out of Yangping Pass to fight like Li Longji, just like Li Longji forced his brother Shu Han out of Tongguan.

But soon this unrealistic fantasy was driven out of his mind by himself: Li Longji's mental retardation during the Battle of Tongguan was no longer an encounter once a hundred years, but an encounter once a thousand years, so he could not count on it.

After thinking about the strategy, Liu Bei and Li Su and his party gradually touched Yangping Pass closer to observe the details.

At this moment, Li Su suddenly discovered a question: "Hmm? I was careless! Why is the road in front of Yangping Pass not just into the pass and the road to establish the pass? Instead, it is a herringbone road. Yangping Pass was built at the top of the crossing of this herringbone?

Wouldn't that mean that if you don't want to go to Yangping Pass to Hanzhong, or just want to go to Sichuan and Chengdu, you can't just pass by "passing Yangping Pass and not entering"?"
Chapter completed!