Quote Originally Posted by TeutonicKnight
Fortress and citadel seiges are absolute meatgrinders, esp before gunpowder. I've lost seiges where I had a 2 to 1 advantage because of all the towers. If I have to go through more than one gate, it's a starvation situation. :)
I call it an "artillery situation."

Seriously some good catapults, trebs, or gunpowder artillery make short work of the walls, and can easily be used to clear multiple levels after eliminating towers from the breached area of the first level. Also note that you can target gates with artillery, and they probably have less HP than chunks of wall, so you'd get through faster.

A pair of artillery units can do wonders for an otherwise tough assault...