Why can a country be defended at a dangerous pass in ancient wars? Ask God for help

Geographically speaking, the passes captured by the ancients were mainly the easiest places to cross a mountain group, so except for these passes, you can only march from the mountainous areas. A typical one is the relationship between Xi'an and Tongguan. If you look at the map of China, you will find that Xi'an is surrounded by mountains in a "C" shape, and the exit of this "C" is Tongguan City, which is even more unique. What's more, if you want to cross this "C" intersection, you have to pass through a huge natural barrier - the Yellow River. That's why Zhang Liang suggested to Liu Bang from Anhui that the capital should be set up here. At the beginning, the Japanese army was heavily deployed by Hu Zongnan and took advantage of natural dangers to block the east bank of the Yellow River, which prevented most of Shaanxi from being invaded by Japan during the Anti-Japanese War. However, there are also cases in history of marching from mountainous areas and suddenly attacking opponents to win. These are called "surprise soldiers". The following is my summary of the reasons why most armies prefer to advance from the plains instead of launching "surprise troops" from the mountains. 1. Traveling in mountainous areas is more difficult than in plains. I think this is the main reason. When I was not out of school, I would watch mountain climbing on TV, and sometimes I would think of how high and fast I could climb if I climbed a mountain. However, after I graduated and started working in the field, I discovered that climbing mountains was much more difficult than I thought. My colleagues and I can only walk up to 5 kilometers a day in the mountains when we are under heavy workload. Generally, after running such a long mountain road, we are too tired to walk, not to mention that we are all experienced mountain climbers for a long time. By the way, there are basically no roads in the mountains, only the narrow paths that people walked in the past. In this case, large transportation vehicles such as carriages cannot go, and food must be carried by the soldiers themselves. In ancient times, the Han people ate millet. Rice, unlike the meat-eating Mongols, meat foods retain high calories, so the Mongols can carry more energy individually to sustain long-distance raids. The Han army must have dedicated food roads. The fastest way to transport food is through plain areas. Even if it is opened a road in mountainous areas, it is not cost-effective. The use of rivers to transport military food in plain areas is also a very common and mature and stable logistics supply. Way. 2. Mountainous areas are less populated than plains. I heard from fellow villagers that the people living in the mountains are descendants of immigrants who escaped war or famine. There is little arable land in mountainous areas, and it is difficult to supply living resources. Often there is only one administrative village in a large mountainous area. So if you capture a town in the plains, you can get new food supplies and laborers, and repair your equipment. 3. It is easy to get lost in mountainous areas. This is what I often felt when I first climbed mountains. We had maps and compasses (and later GPS) but we often deviated far away from the planned route. We often only found out that we were on the wrong track when we reached the mountain road. Probably because people have little vision in the mountains and there are no obvious reference objects (there are many similar terrains in mountainous areas, which can easily confuse your memory of the route). If you are not familiar with the terrain before, then it is best not to play "Donkey Travel". You see, the news often broadcasts the disappearance of "Donkey Travelers", right? Based on the above, if you want to march into a certain place, you usually go from the plains. If you have to, for example, if you encounter places like Chengdu, Xi'an or Taiyuan, you can only settle for the next best thing, but you should also choose some areas that are easier to cross. In mountainous areas, military strategists on both sides will realize this and will set up passes in these places. This is why in the past battles always had to capture the pass.

I hope it will be helpful to you and hope you will adopt it