As we all know, in the history of mankind, war has almost never stopped, and peace is always a small time. The fundamental reason is that there is a strong contradiction between the limited productive forces and the growing population. Since the founding of the Zhou Dynasty, the vassal states began to conquer each other, but defeating each other's troops is not the ultimate goal of the war, but a necessary process.
Therefore, for both sides, the best way to fight is to take the enemy's important cities by stratagem, and finally only need to negotiate cession. After all, losing a city with strategic significance basically means that the enemy has lost its ability to resist.
In this way, the number of cities occupied represents the strength gap between the two sides. Therefore, as long as they can occupy the city through diplomacy or conspiracy, the generals will not use force. Military conquest will not only cost people money, but also lead to the emptiness of one's own territory and be used by others.
However, force has always been indispensable. After all, there is always a time to talk. However, this is the next strategy, because it is more difficult to attack the city than to defend it. Strategists pay attention to "surprise, surprise". If you are besieged, it is hard to say. It takes a lot of time and energy to grind people. You should also be alert to the enemy's reinforcements. For example, when the Mongolian army besieged the fishing city, it had been besieged for 30 years.
On the other hand, ancient cities generally extended in all directions, with gates in all directions, including a main entrance. Relatively speaking, the main entrance is larger than other city gates, and there are many organs and loopholes, which are all built with reference to the city gates in the border area. They are heavily guarded all the year round. In case of emergency, they will strictly check people entering and leaving the city gate, or even close the door altogether.
In a war, if you want to attack a city, you must first occupy the enemy's gate. Unfortunately, the ancient city gates are generally built according to the terrain, usually on the main roads or dangerous passages. The effect of "one person does not open the door" can be achieved in wartime.
So here's the question. Because the practice of blind combat will cause great losses to our army, and long-term siege will also lead to low morale and lax morale. Then, why don't these generals directly bypass this hard bone and lead their troops deep behind enemy lines to capture the city with weak defense? On this issue, no one has ever thought about it in history, but in the end, no one dared to try again.
In other words, it is also because of the terrain. Because these cities and gates are located on the main roads or important passages, they often completely block the marching route. If you want to walk around the city, it means that the marching route will obviously become longer, which may be dozens or even hundreds of miles.
Moreover, the long March around the supply line will inevitably increase the pressure on manpower and material resources, and also test our logistics and transportation capabilities. Moreover, the grain convoy is in danger of being cut off by the enemy at any time. Third, marching around the field may lead troops to March on unfamiliar terrain, which is full of unknown factors. If they are unfortunately ambushed, they don't even know the direction of retreat. Therefore, for strategists, "going deep alone" is a taboo.
In contrast, although the siege has a great loss of troops, it can effectively avoid the above risks, or it can be looted after breaking the city and then sit in the new city. It's much easier and more cost-effective than walking around. Therefore, when the army cannot besiege the city for a long time, there are usually only two options, either to send more troops to continue fighting or to withdraw all troops.
In any case, it will never choose to bypass. From this point of view, although modern people are better than the ancients in science and technology, the ancients may not be worse than modern people in using terrain advantages in war. After all, this is the ability to defend the country. If you don't master these skills, you may be in danger of destroying the city and killing people.