I was defending a siege in a well developed castle. After my troops destoryed siege towers (both of them) and battering ram, the attacking AI just stood at the gate standing there just to be killed by my archers. The problem is, that when attacker has siege tower, there is no ladder spawning on that flank. This time, the towers were on both flanks, so there were no ladders, and the AI could not acces the castle. The battle took over 2 hours (after 15 minutes I jumped off the walls just to fast forward the battle). Check the battle time and causalities of both sides. They did aboslutely nothing to the defenders. The problem is 2 things - one that there is no spawning of ladders, so attackers can not reach the castle if both siege towers and battering ram is destroyed; and the second problem is of AI - if it can not possibly attack the castle, they should just retreat from battle.