Funny thing is that some people experience certain game features far more often than the others; personally, I never took notice of rebel assassins, and stated so in a thread few days ago, but ever since I have caught about two dozens of them in various provinces. Odd, indeed.

As for the AI assaulting castles, it has happened to me few times by now, last time it happened was last night, I had only some 30 troopers in a surrounded castle, I believe it was on a fairly low level of a fort or something, and they attacked with some 700 men. I auto resolved, since I didn't want to bother with that.

My personal favor was AI attacking a citadel of mine; two battered units of plain spearmen, each some 15 soldiers, and few other tattered remnants. The AI went after the gate, yet unfortunately - for him, or it… whatever - the AI came from a far side and was forced to walk along my walls while my fire towers reigned death upon their ranks. And since the AI had virtually no siege engines (most unfortunate), I managed to kill some 600-700 of enemy soldiers without one single casualty. It was hypnotizing; one unit would march toward my gates, would waver and rout, return, suffer some more casualties and then it would rout for good, other single enemy unit would step in and so on and on…