Quote Originally Posted by rory_20_uk
It seems the AI likes to attack castles / towns as soon as it has one ladder, one siege tower and a ram. The tower dies, the ram takes the gates and the ladders get one attacking unit routed from the walls. Sometimes ballistas and catapults mobilise up to the walls.
This is very true. If large AI armies used about 3x to 4x more ladders/towers, they would be far harder to defend against.