In February 234 AD, Zhuge Liang raised 100,000 troops, with sufficient grain and grass, and poured the country out of the valleyAnd Emperor Wei Ming also attached unprecedented importance to it, not only sent Qin Lang, the protector of Shu, to lead 20,000 troops to reinforce Sima Yi, but also issued an edict repeatedly instructing Sima Yi to adhere to the turtle strategy and fight a war of attrition with Shu Han, don't be afraid of being embarrassed, I resolutely support you: "But the strong wall refuses to defend to frustrate its edge, he has no ambition to advance, he has no way to retreat, and if he stops for a long time, he will run out of food, and if he has nothing to gain, he will go." Walk and chase it, wait for work with ease, and the way to victory. "
In April, the Shu Han Northern Expedition army walked out of the valley and came to Yixian County, south of Weishui;And Sima Yi's army also crossed the Weishui and camped in Weinan to hold on to Zhuge Liang. And at this critical moment, Sima Yi made a mistake in judgment, he said: "If Liang is out of martial arts, he will be worried about the mountains and the east;If you go west to Wuzhang Plain, you will have nothing to do. "Sima Yi thinks that if Zhuge Liang goes out of the east and marches to Chang'an, it will be bad, and we can only fight to the death;And if he goes west to Wuzhang Plain, we will be fine, just stay here and hold on until they run out of food and retreat. 
If Wei Jun really did what Sima Yi had instructed, then they would be finished. Because although Zhuge Liang is out of the customs this time, his goal is not Chang'an, he is still Longxi, it has always been Longxi, and it has never changed. The reason why he went west to Wuzhangyuan was not to see the strength of the Wei army and temporarily avoid the edge, but to try to confuse the Wei army, and then take the opportunity to cross Weishui from Wuzhangyuan to the north and seize the opposite Beiyuan, so as to cut off Weishui and isolate Longxi, so that he could take it calmly. It's a pity that although Sima Yi couldn't see through Zhuge Liang's strategy, his subordinate Guo Huai saw it. In everyone's impression, Guo Huai is a very inconspicuous character in the history of the Three Kingdoms, but in fact, he is quite powerful, quite powerful, quite powerful, quite powerful, and important words have to be said more than three times. In that year, Liu Bei captured Hanzhong, Cao Wei's main general Xiahou Yuan was beheaded, the Wei army broke its courage, and it was about to collapse, it was Guo Huai who collected scattered soldiers, stabilized the army's heart, and planned to go far from the Han River and lined up, so that Liu Bei was suspicious and did not dare to cross the water to attack;Otherwise, if you don't wait for Cao Cao to come to help, I'm afraid that Hanzhong has fallen into Liu Bei's hands. Later, Cao Pi ascended the throne, and worshiped him as the assassin of Yongzhou with Guo Huai's great merit, and took charge of the work of Cao Wei in the northwest. According to historical records, every time a Qiang Hu came to surrender, Guo Huai could quickly and in detail tell the other party's information, and there was no need to check the household registration at allThe ethnic minorities are relatively simple, and they think that Guo Huai really has a clever plan for an unpredictable prophet, and they call him a god and respect him very much. 
Later, Zhuge Liang's first Northern Expedition unexpectedly entered Longxi, Cao Wei was shocked, only Guo Huai, the assassin of Yongzhou, seemed to have foresight, and actually came to Tianshui from Chang'an in advance. So when Zhuge Liang entered Longxi and the counties rebelled against Wei in response, Guo Huai was able to stick to Shangti, reversed the situation, and persisted until the arrival of ** reinforcements, and then seized the opportunity, while Zhang He's 50,000 army attacked Jieting, he decisively killed Shangti, and broke Ma Tan's Houzhen Lieliucheng from behind, and Shu Hansu was defeated by Gao Shen. Gao Shen was not punished by Zhuge Liang like Ma Tan, Li Sheng, Zhang Xiu, Huang Xi, and Zhao Yun afterwards, which shows that he should have fought quite tenaciously, and failed only because Guo Huai was too powerful. Later, Zhuge Liang went out of Qishan again, and it was Guo Huai who made a contribution to collecting grain and kept Longxi again. And this time, it turned out to be Guo Huai who turned the tide, and through careful analysis, he saw through Zhuge Liang's strategy, and finally buried Shu Han's Northern Expedition. It turned out that in the optimistic atmosphere of Wei Jun, Guo Huai discovered a terrible suspicion. It is reported that Shu Han was sending people to Tuntian at this time in a place called Lankeng (Note 2), which was not much to pay attention to, but the problem was that it was located at the junction of Wudu County and Cao Cao Tianshui County of Shu Han, and was close to Qishan, an important town in Longxi. Therefore, Guo Huai had doubts in his heart: If Zhuge Liang intended to be in Guanzhong, then why did he send someone to Tuntian on Qishan Road at this critical moment!Note 2: Located in the northwest of present-day Chengxian County, Gansu Province, volume 20 of the "Shuijing Note": "Jian'an Water and East Path Lankeng City North, Jian'an Chengfu, its place is also the Licheng of Xixian County." Suddenly, a flash of light flashed in Guo Huai's mind: Oh no, Zhuge Liang didn't want to capture Guanzhong at all when he went north to Guanzhong this time, his goal was still Longxi!Thinking of this, Guo Huai immediately ran to report to Sima Yi and said: "Liang Jin is going west to Wuzhang Plain, and he will cross Weishui in the north to fight for the Northern Plains, so it is advisable to base on it first." "The generals don't think so, why did Zhuge Liang divide his troops to fight for the Northern Plains?Isn't this a split of forces in two, so that we can break each one?No way, no way. And the leader has already set the tone, as long as the Shu army is stationed in Wuzhangyuan, we will sit back and relax, but you are alarmist here, and the leader will put his face on the groundGuo Huai was in a hurry and hurriedly explained: "If Liang crosses the Weideng Plain, the army is in the north mountain, isolating the Longdao, shaking the people and razing, this is not the benefit of the country. When Sima Yi heard this, he immediately patted his head: Oh, why didn't I think of it, I almost missed a big event, so I quickly sent troops to seize the Northern Plains, otherwise the big thing will go!It turned out that there were two passages to reinforce Longxi from Guanzhong. One is along the Weishui River valley from the Chencang narrow road into Long, and the other is the Guanlong Avenue that crosses Longshan from Weishui and Qishan (Beishan). Among them, the Chencang narrow road is too narrow and not suitable for large-scale marching;The Guanlong Avenue is wide and flat, which is the main road into Longxi, and it is also the passage for Zhang He to enter Longxi. Once Zhuge Liang occupies the Beiyuan and builds a military stronghold on the Beishan Mountain, 20 kilometers north of the Beiyuan, with a small number of troops, he can cut off the Weishui and Guanlong Avenues and form the Wuzhangyuan-Beiyuan-Beishan defense lineIt can even open up the thin two counties of Anding and Northland to the north, and connect with Xianbei Kirby. In this way, the entire Guanzhong Basin will be cut off by Zhuge Liang, and the situation in the western part of Cao Wei will be greatly damaged. 
Here it must be explained again from a military point of view. The so-called "isolation of Longdao" is not to line up and seal the entire passage. Rather, it is enough to build a siege and fortification at key strongholds, which is enough to radiate this large area of the perimeter (Note 3). If something happens in Longxi and Cao Wei rescues, these nails must be removed, otherwise even if the army passes, the grain road will be frequently harassed. Most of the condescending sieges are easy to defend and difficult to attack, and even ten times the number of troops may not be able to take it in ten months (see Zhuge Liang's attack on Chen Cang). In short, if Sima Yi ignores these strongholds, Longxi has been isolated from the east for a long time, and the people's hearts will will inevitably be shaken after a long time, so Zhuge Liang can lead the line with the point, and lead the area with the line, and divide the troops to gradually divide and encroach on Zhou Yuan, Chen Cang and LongxiAnd if Sima Yi wants to pull out these nails, it will inevitably affect the main force, and Zhuge Liang can come out of the nest after getting the news to achieve the purpose of frontal field battle with the main force of the Wei army. Note 3: That is, a fertile area under Qishan Mountain, which is the birthplace of the Zhou people, known as "Zhou Yuan is full of flesh, and violet is like a syrup" ("The Book of Poetry, Daya Cotton") Of course, it is a pity that Zhuge Liang's extremely clever move was seen through by Guo Huai. I insist that Guo Huai was the most underrated person during the Three Kingdoms period, he seemed to be low-key, but his strategy and even life planning were very sophisticated. If you don't believe me, we can take a look at his resume. 
Guo Huai, the word Boji, he was born in a famous family, is the eldest son of the Taiyuan Guo family, his grandfather Guo Yi is the Eastern Han Dynasty Dasi Nong, his father Guo Yi is the Eastern Han Dynasty Yanmen Taishou, the late Han Dynasty famous character comment leader Guo Linzong is also from his clan. Therefore, Guo Huai made his debut as filial piety and honesty, and had the standard configuration of the scholar family, and at the beginning of his career, he chose to invest in the five senses Zhonglang to serve as Cao Pi's disciple Cao, and since then he has become Cao Pi's descendant;Later, Guo Huai followed Cao Cao to Hanzhong, and then stayed in the army for Xiahou Yuan, and got on the line with Xiahou again. After the defeat of Xiahou Yuan, he strongly promoted Zhang He as the interim coach, and since then he has established a good relationship with the last five good generals. In addition, he also married and formed alliances with the Taiyuan Sun, Wang, Wen and other fellow villagers to reach a community of political interests. In short, Guo Huai has people in both the military and political circles, which is the so-called "relationship is a bit hard, the road is a bit wild, and the roads are smooth"!Therefore, no matter whether Cao Zhen, Sima Yi or later Xiahou Xuan were the governors of Yongliang, they had to try their best to win over Guo Huai, the assassin of Yongzhou. After the Gaopingling Incident, Sima Yi even expressed Guo Huai as the general of the expedition to the west, and the governor of the Yongliang military and became the commander of Shu. Guo Huai had two famous nieces, one married Pei Xiu of the Pei clan in Hedong, and the other Guo Huai married Jia Chong of the Jia clan in Hedong, both of whom were the founding heroes of the Western Jin Dynasty, and Jia Chong was the elder brother of Emperor Hui of the Jin Dynasty (Note 4). In short, through many years of military management, as well as the blessing of the network of subordinates, fellow villagers, and relatives, the Taiyuan Guo family gradually began to rise in the military and political worlds, and each generation of famous generals has produced the best generals in the Jin Dynasty, Northern Wei Dynasty, Western Wei Dynasty, Sui Dynasty, Tang Dynasty and other dynasties. After the early Tang Dynasty, the Taiyuan Guo clan developed into one of the eight major surnames in the Central Plains, and its reputation was prominent at that time. Guo Ziyi, a famous general in the Tang Dynasty and the greatest contributor to the pacification of the Anshi Rebellion, was after Guo Huai. 
In short, Guo Huai was a low-key cattle man, and he was also his own person in the scholar clan (Note 5), which was not the same as treating Zhang He, and the two were still in the Cao Pi shogunate at the time, so Sima Yi naturally took his opinion seriously, so he announced on the spot that Guo Huai would lead the elite troops to occupy the northern plains first. As a result, when Zhuge Liang sent a large army to occupy the northern plains, he found that Guo Huai had taken the lead and had built most of the camp trenches, and the two sides fought fiercely, and Guo Huai repelled the Han army with fortifications. Note 4: Scholars such as Yano Zhushui, Liu Zenggui and Peng Wei have found that the intermarriage network of local clans in the Han Dynasty was generally within the county or adjacent counties. Taiyuan and Hedong are neighboring counties. Note 5: In fact, the military resources of the generals of Guan Long were an important support to support the Sima clan's later control of the central power of Cao Wei and the completion of the Wei and Jin dynasties. Especially during the struggle for power between Sima Yi and Cao Shuang, Xiahou Xuan, the governor of Yongliang, was originally Cao Shuang's confidant, but because Guo Huai's generals were devoted to Sima Yi, Xiahou Xuan was basically hollowed out during his tenure and failed to play a role. And Sima Yi also reciprocated the favor, and treated the Guo family quite kindly, and after the failure of the rebellion of Taiwei Wang Ling in the third year of Jiaping (251), he was ordered by Sima Yi to Yi clan. Guo Huai's wife was Wang Ling's sister, and she should have been executed, but as soon as Guo Huai pleaded, he was immediately fine. Zhuge Liang sighed, it seems that there are masters in the Wei army!If this plan fails, let's do it again. A few days later, Zhuge Liang again attacked the Northern Plains on a large scale. Sima Yi's northern defense line is a long encirclement, and Zhuge Liang's army is moving westward, so Cao Wei's generals all think that they should immediately increase their troops to the west, only Guo Huai thinks that Zhuge Liang is attacking the east from the west, and we should increase our troops in Yangsui in the east. Sima Yi once again recognized Guo Huai's judgment and sent Guo Huai and the general Hu Zun to lead troops to reinforce the Yang Sui guard general Zhou Dang (Note 6). Sure enough, it was night, and Zhuge Liang's army launched a night attack on Yangsui, but Cao Wei had already prepared, and Zhuge Liang failed to succeed. 
Now Zhuge Liang is out of line. To the north, Guo Huai was condescending and well-defended;To the east, Sima Yi's main force occupies the horse mound, according to the danger (Note 7), Zhuge Liang wants to enter but can't enter, wants to fight but can't fight, Cao Wei is all turtles, one by one deep ditch and high base, just don't fight with you, what can I do!was scratching his head, Zhuge Liang suddenly had another plan, and hurriedly ordered someone to call Meng Yan, the general of the auxiliary Han and the tiger step supervisor of the Chinese army, so and so, and so and so and so and so and so on. After the order, Zhuge Liang couldn't help but say to Meng Yan with a little apology: "Liang also knows that this plan is too risky and difficult to be a general;."But for the sake of the great cause of rejuvenating the Han Dynasty, I hope the general can understand. Meng Yan smiled: "If you don't enter the tiger's den, you can get the tiger!."The southerners received the grace of the prime minister, and they should repay the grass and the ring, and they were not afraid!Note 6: See "Book of Jin Xuan Di Ji": "Sima Yi) sent the general Hu Zun and Yongzhou Assassin Guo Huai to prepare Yang Sui, and Liang met in Jishi, fought in the plain, Liang could not enter, and returned to Wuzhang Plain. Note 7: See Zhuge Liang's "Book with Buqi": "The horse mound is more than ten miles east of Wugong, and it has high potential, and it is inconvenient to attack, so it is to keep ears. ”