Name that band!

Anyways.

In my most recent small map normal/normal game I added extra factions to fill up the map better.

I'd say the majority of the AIs killed themselves with horrifically poor management of their sovs.  It's rather depressing since I didn't get much chance to off any of them myself. I killed one.  The more aggressive AI probably took out a couple, but I'm pretty sure most killed themselves.

Most of it is attacking against really bad odds or against troops they can't possibly defeat.

It all pretty much coincides with decent party/squad appearance.  The AI is really bad at evaluating party strength - theirs or others.

I usually make a unit I call a maceman - it's a party (4) with all leather armor, medkit, and mace.  So they're reasonably strong and have defense (I don't do glass cannons and auto almost all my fights).

I was romping all over the last AI's lands and I'd leave one of those to hold captured cities I didn't raze.  The AI would send catapults, weak squads, NPCs with a few weak squads, at my macemen over and over and all they did was die, die, and die some more.  If the AI would group up the 3-4 units to make one decent assault, they might stand a chance (unlikely, but it could happen) - but trickling in with friendly units around, one at a time, is just dumb.