During the Three Kingdoms period, Zhuge Liang, prime minister of Shu and Han Dynasties, made a northern expedition to Cao Wei. General Wei Yan clearly put forward the famous meridian valley strategy: imitate Han Xin to build plank roads and dive in. Wei Yan personally led 5,000 elite soldiers from Woods Valley to Chang 'an and won Chang 'an and Tongguan in one fell swoop. Zhuge Liang's elite soldiers sent troops from Gu Jie to Chang 'an and Tongguan, and the two armies met in Tongguan in different ways.
The meridian valley is vertical from east to west, north to south, and is about 330 kilometers long. From the southwest Qinling Mountains in Chang 'an County, Shaanxi Province in the north to Shiquan County in the south; The north entrance is called Zikou and the south entrance is called Zikou. There are thousands of suspended plank roads on the cliff of the Meridian Valley, and the reason for the danger depends on the Qinling Mountains. Qinling Mountain, also known as the Mid-South Mountain, is high in the west and low in the east, which is the dividing point between the Yangtze River and the Yellow River. The meridian valley is among them, which is extremely dangerous and obvious.
Before Zhuge Liang's first northern expedition to the Central Plains, Wei Yanming did put forward the famous plot of the meridian valley. But Wei Yan thought Zhuge Liang refused, which means Zhuge Liang was decisive and didn't need this strategy. Later generations thought that Zhuge Liang was too cautious, and the plot of Meridian Valley without Wei Yan was a great failure and missed an excellent opportunity. Some people think that Zhuge Liang had no choice because Zhuge Liang was not prepared to attack Chang 'an. His aim should be to take Liangzhou first, then slowly but surely, and gradually devour Cao Wei.
First of all, in Bian Xiao's view, after Wei Yanming did put forward the meridian valley plan, Zhuge Liang often did not adopt it. The reasons can be divided into the following aspects. On the one hand, the cavalry attacking Chang 'an has really changed too much. We can't send many soldiers, because Wei will find more people. However, the number of people sent cannot be small, because Chang 'an is a relatively large fief, not an ordinary town. Chang 'an is the ancient capital of Xi and the first imperial capital known as the capital in history.
Zhou Wenwang has its capital here and has Fengjing. After Zhou Wuwang succeeded to the throne, Hao Jing was built, which was collectively called Fenghao. Xi 'an is usually called a pickaxe. In the fifth year of Emperor Gaozu (the first 202 years), Chang 'an County was established, and Changle Palace was built on the basis of Longzhou Bay of Weihe River, the northern end of Epang Palace and Qinxingle Palace. In the seventh year of Emperor Gaozu (the first 200 years), a Weiyang Palace was built. In the same year, the city moved here from Oak Yang. Because it is located in Chang 'an Township, it is called Chang 'an City for the sake of stability and unity. Therefore, it is obvious that Chang 'an is a solid city, with sufficient grain and grass supply and long-lasting time. Therefore, if Wei Yan wants to lead an army to attack Chang 'an, it is not enough whether it is 5000 troops or 1000 elite soldiers.
From this point of view, Zhuge Liang is decisive and does not need Wei Yan's meridian valley plot, which is obviously a wiser choice. On the other hand, in Huang Chu (220), Cao Pi ascended the throne under the influence of Zen and established the State of Wei. In Xiahou, he served as General Anxi and held sacrifices. After Xia Houyuan, he was stationed in Chang 'an in prison. In Wei Yan's view, Xiahou is a hypocritical person. As long as his elite soldiers successfully captured Chang 'an, Xiahou Mao would abandon the city and flee. For this matter, in Bian Xiao's view, Wei Yan's distinction is rash, that is to say, unreliable.
To say the least, even if Xiahou escaped, Wei Yan could be caught as long as his generals stayed out of the city and organized reasonable defense in Chang 'an. As long as Wei Yan can get Chang 'an soon, he will be interrupted by reinforcements arrived by Cao Wei. During the Three Kingdoms period at the end of Han Dynasty, Chang 'an was the key fief, and its influence was second only to that of Luoyang, the imperial capital of Cao Wei. Even if Xiahou is really brave, he should understand a big truth. If he escapes from the city, he will die regardless of the outcome. But as long as we persist, we will not be easily punished by the Cao Wei dynasty, and we will still have the opportunity to develop and innovate.
More importantly, Chang 'an is not far from Luoyang. As long as we persist in not fighting, we will win by waiting for reinforcements. In the eyes of many historians, if Zhuge Liang's troops could not attack Chang 'an for a while, once Cao Wei sent two reinforcements, they went all the way to the rescue site in Chang 'an and cut down the meridian valley all the way, cutting off the back road of the Han army. Then the meridian valley plan implemented by Wei Yan is equivalent to sending a head. Of course, such an exploration plan is not easy for Zhuge Liang, the prime minister of Shu Han who has always been cautious. In addition, Wei Yan's meridian valley strategy is inconsistent with Zhuge Liang's Northern Expedition. For Zhuge Liang, he prefers to attack Longyou, Liangzhou and other places first, and then attack the Guanzhong area to which Chang 'an belongs.
Finally, Longyou is a perfect place of victory, with Qinling Mountains and Han Shu in the south, Hexi Corridor in the west, Yellow River in the north and Longshan in the east. Longshan, in particular, is bordered by Weishui in the south and the Yellow River in the north, stretching for hundreds of miles. The decorative partition between Longyou and Guanzhong is a sexual climate to resist Cao Wei's counterattack. Because Longyou has this advantage, it can send troops to defend the port of Longshan after the virtual break, stop the attack of Cao Wei, and make Longshan break to the west. In the spring of the sixth year of Jianxing (228), Zhuge Liang sent troops to three counties (Tianshui County, Nan 'an County and Anding County) in Longyou, and gained first and then lost. Suspected soldiers are in the inclined valley, leading elite troops to attack Qishan. Zhang He broke Ma Su in Jieting, and Zhuge Liang returned to Hanzhong from Xixian County 100.