Siege Cavalry question

If an enemy army is made up of Cavalry and Infantry, with the AI always charge it's cavalry regardless of how far behind the infantry is?

Tolhouse(sp?) was being sieged this morning from a full stack of Spanish origin. It was a citadel at the time they attacked, where you have the three distinct wall/gate sections. I only had about 1/3rd of a stack in defense, and when the game started they were all over the place. So, I pulled everyone all the way back to the central square where there are only two gates and they are somewhat close to each other.

The spanish charged their cavalry all the way into the back of my citadel, and crashed upon my Noble Swordsmen/Dismounted Fuedal Knights. It was another 4-5 minutes before the rest of their troops arrived and their cavalry was pretty much gone after the first minute. Is that just another example of bad AI, or where those nutters just a rarity?

I've had a few like that when in a fortress or citadel. You see 1 or 2 unit moving way ahead of the others and getting themselves slaughtered.

Probably the AI decided immediately that it should rush the square since there would be no resistance anywhere else... and it doesn't know enough to keep faster troops even with slower ones. Consequently, the AI units pull apart from each other and arrive at different times, presumably because it just ordered 1 attack command to all units from whenever your walls got breached. If you had units at other places in the city to give resistance, it would probably be less likely that this would happen. The AI would devise more interesting plans (okay, maybe only slightly, but still) to take on the nearby threats, and afterwards probably end up at the square in a much more cohesive fashion.

The one time that I remember rather well, I was in a fortress with a somewhat minimal army. The enemy spy had opened the gate and launched a surprise attack. The first thing I did was pull all my soldiers to the inner wall. So that would agree with your theory there Foz.