Why didn't Zhuge Liang adopt Wei Yan's fantastic ideas about the meridian valley?

After the establishment of Shu Han Dynasty, Prime Minister Zhuge Liang wrote to his late master many times, and made a northern expedition to Cao Wei. General Wei Yan presented the famous "Wonder of Woods Valley". But after weighing the pros and cons, Zhuge Liang did not adopt Wei Yan's suggestion. Wei Yan was depressed for a long time and repeatedly complained that Zhuge Liang was too cautious and timid.

But is Zhuge Liang really timid, as Wei Yan said? We might as well look at what kind of road the meridian valley is first, and then talk about the meridian valley.

Hanzhong and Guanzhong areas are separated by Qinling Mountains, and six highways cross the Qinling Mountains. They are: Chencang Road, Xiexie Road, Luo Luo Lu Road, Woods Road, Ku Valley Road and Wuguan Road. The Qinling Mountains are high in mountains and deep in valleys, and most of these six passages are rugged and difficult to walk. The meridian passage (i.e. meridian valley) is the most dangerous passage. Where the meridian passes, the terrain is dangerous, the roads are rugged and the weather is unpredictable. Therefore, there is a saying that "there are six roads in Qinling Mountains, and the meridian is king".

It's not just the rough roads. Wei Yan said that he would sneak into the Meridian Road with 5,000 soldiers and 10 days' rations, which is obviously a fantasy. The meridian passage is more than 300 kilometers long and it is difficult to walk. In the case of fierce fighting, it is almost impossible for soldiers to walk out of the meridian valley in 10 days.

To say the least, even if Wei Yan can cross Ziwuling safely and raid Chang 'an. That's just going deep alone. And marching from Ziwuling, Wei Yan will definitely not carry a lot of war horses and siege equipment. It's daydreaming to capture Chang 'an with only 5,000 infantry. Moreover, when we get to the gate of Chang 'an, I'm afraid there is not much food left for 10. As long as Wei Jun doesn't stick to it, the Shu army will break up on its own without food and grass, and it is impossible to form a camp with Zhuge Liang from the oblique valley.

Moreover, the total strength of the Shu army is far from that of Cao Weijun. Even in Guanzhong and Wei Jun, Wei Jun still occupies the danger of the city, and the rear of the Shu army is the rugged Qinling Sixth Road, so the guarantee of logistics materials is very problematic. This will undoubtedly become the battle of the Shu army's national subjugation. What will be wiped out will only be the Shu army without terrain support and logistics support.

Wei Yan's so-called whimsy is actually an armchair strategist without a strategic mind, and a dogmatism of scheming for the sake of scheming.

It is this that Zhuge Liang saw that he would not hesitate to reject Wei Yan's plan. In fact, many people follow Wei Yan's example and try to cross the meridian passage. When Cao Zhen and Sima Yi attacked Shu, they also tried to March from the Meridian Valley. Huan Wen of the Eastern Jin Dynasty also wanted to sneak into the Meridian Valley. Without exception, they all ended in failure.

Whether inferred from the history of later generations or combined with the actual situation of Shu at that time, the so-called "valley" was a downright bad idea. It not only dispersed the extremely limited forces of Shu, but also could not contain Wei at all. It is reasonable for Zhuge Liang not to adopt Wei Yan Zhi's plan.