The moat, as the name suggests, is used to protect the city. In ancient times, there were no such powerful cannons, and the general city walls were ridiculously thick. Judging from the wall as thick as Daliangmen in Kaifeng, it felt really real. It makes you feel desperate just looking at it. In addition, the deep and wide moat makes it impossible to attack. Therefore, Sun Tzu's Art of War also said that the general will attack the strategy, then attack the enemy, then attack the army, then attack the city, and then attack the city. The city is the most difficult and least important thing to do.
First of all, the city walls are very high. The Daliangmen city wall is 26.3 meters high. And like some big cities, such as Nanjing and Beijing, the walls must be taller and trenchier. How to attack a city? One is the long-range trebuchet. Of course, it is often very difficult to hit the city gate just in time and destroy it, because the city wall is very thick, and many trebuchets do not necessarily just hit the city wall or the soldiers on the city wall, there are many whooshing. All of them were smashed into the city, destroying most of the houses and injuring many innocent people. Therefore, unless the soldiers and civilians are all anti-people in a few years, or lunatics who don't care about the civilians at all will use trebuchets endlessly.
Otherwise, it is to break the city gate, just like what is often shown on TV. Under the cover of a group of people holding shields, another group of people carry a long pillar to hit the city gate. However, some big cities in ancient times There is a suspension bridge. When the suspension bridge is raised, there is a moat in front of it. There is no way to get close to it, and it is impossible to swim across it with such a heavy thing. I am afraid it will sink if water enters, and the water in the big city will be dug very deep.
There is also a cloud ladder. Get a very high ladder and climb up the city wall. Climb up and kill the defenders. Open the city gate and put on your own flag. Basically, you will declare that the city has been won, because it is the most difficult. It means to attack the city. It would be difficult to get across even if there is a water ladder. You can't carry the ladder and swim over. Even if the ladder is very high and can span both sides of the moat, who has the lightness skills to run on the ladder, and it is still above it? For archers, it is inconvenient to swim through the water. Wearing a heavy armor is already inconvenient. If you swim over, isn't it a target? And even if you attack the corner, there will be hot oil and rocks hitting you.
So, for some big cities, storming by force is often not the first choice, because to storm a city often requires three times the number of enemies before you can try it, and it may not be successful. If you win, you will kill a thousand enemies, and you will lose yourself. Eight hundred, so under the defense system of high walls and deep ditches, most of them were besieged cities. The siege would stop food and grass inside, and the people inside would eat people until they surrendered.