Here's a combat question - or maybe it's more of a scenario, or something I just don't understand. I've seen it happen many times - here's an example.
I'm in the last stages of assaulting an AI city. I've bombarded the defenses down, suicided a bunch of Cannons/Artillery. Before the battle started, the AI had 30 defenders, I had about that many attackers (plus siege). 27 defenders are dead now.
There are 3 defenders left: A Cavalry, damaged but still at 9/15 STR, and 2 badly damaged Riflemen (down to 2.4 STR each).
I have 3 attackers left: One is a healthy Infantry, and the other 2 are Crossbows (yeah, I should have upgraded them... just ignore that part).
If I attack with a crossbow, the Cavalry will kill it. But if I attack with the Infantry, trying to take out the top defender, one of the Riflemen will defend... and then my Crossbow(s) will lose to the Cavalry.
Why, in this situation, does the top defender not defend against my Infantry? Does the AI know that no matter what defender it uses, the Infantry will kill it, and therefore it saves its best defender to fight my weaker attackers in the subsequent rounds?
If the AI's combat logic is programmed this way, why doesn't the worst defender defend all the time? In most situations like the one I described, my top attackers - the Tanks, CR3 Infantry, etc - are getting 95% odds in the early rounds of the assault. Why wouldn't the AI save its top defenders against my weaker attackers, if they don't have anything that could stand up to my top attackers?