My greatest battle wasnt a particularly surprising one. I was playing as spain, and milan kept pissing me off so i sent a half stack of knights into them (fairly expensive but it turned out to pay for itself). So after winning a few minor battles, milan throws a full stack at me but it turns out it was just a bunch of archers with a few heavy units backing them up.

No surprise what happened to them, they got massacred since well, archers cant really handle knights when the heavy infantry they did have where scattered. It wasnt some epic strugge or anything but seeing countless enemy soldiers get thrown around like that was fun.