I had an large army of Franks trespass in my territory so obviously I thought they clearly want war, so I declared war on them. Anyway, the next turn a full stack Frankish army besieged one of my towns which had very little men in it. So I thought I lost that territory then, but to my suprise they asked for a peace treaty while besieging it, I accepted then they went away. And it turns out the Franks were trespassing as they were after an army next to my territory so they just came through.

Gotta say I'm impressed with this AI but they could have just asked for military access lol.