[Award Winner] Fortifications I: How to build a fortress

[Hoel]

We'll add a moat to our fortress. There's two kinds. The dry moat, more or less a big ditch that adds problems for seige towers and ladders. We can also make a wet moat, that's a channel filled with water, this is can be a wholly man made afair, with stagnant rain water but it's not very good, a dry season can make it a dry moat fast. If we have access to a river or stream we can use it to fill the moat.
I if the enemy breaches the first wall they're in the fortress and we have lost. If we add another layer to the fortress, they will have to breach both walls to get in.
First, lets make another wall. It will use the terrain to force the enemy to attack uphill where possible (never below a slope, always on the top) and make use of natural water for a ready made moat. The courtyard of this layer of wall will probably house some of you essential services so make some room, but not too much. If the enemy breaches the wall instead of going over and taking them from you, you will still have defenders on the wall to combat them and you will want to keep the enemy in reach of as many of your defences as possible. If you have room.
Now add the gatehouse and the towers as before, minimizing open stretches of wall. To give the attackers a harder time, make the way from gate to gate as long as possible. Put the gate opposite to the gate to the main fortress, or seal them in with a wall so that they have to go around an almost complete circle.
Finally, we can make one more addition to this layer. If they think it's difficult to breach one gate, why not add two. Put a small courtyard right behind or in front of your main gate and add another gatehouse.
This process can be repeated for a third layer.