Defeats? I've had a few. Actually, I've had a shedload, but anyway...

Best recent one I had was a Serbian High bridge defence. I was a bit green with the Serbs & didn't really know their unit roster that well, & it was against an equal in numbers mounted Cuman army consisting of large numbers of HAs & Steppe Cavalry & one unit of Cuman Heavies (a prideful, brave beyond belief Prince, no less). Four star princey on the pagan side & one-star provincial governor on mine (leader of a unit of HAs chosen for his acumen, not his fighting ability).

I set up my Voynuk swordsmen in front of three ranks of Shielded Bowmen; on the flanks I had four units of Pavise arbs (two each side). I had one unit of Vlastela heavies sitting back with my general out of bowshot range.

Everything went swimmingly with Cumans being decimated en masse from controlled missile fire, until the prince charges across the bridge bringing his last two whole units of HAs with him. I open up with everything I've got on the princey, thinking, "This'll do it".

Nada. The HA get in the way of my missiles, I get about a third of the CHCs, he smashes straight through the swordsmen (think: Exocet missile through butter) & into the shielded bowmen who scatter in terror. The HAs murderlise my Pavs & half a unit of Steppeys have rallied & followed their bossman over to destroy anyone brave (foolish?) enough to rally.

So, here I think: "Vlastela heavy cavalry, they look like knights, they move like knights, they certainly cost enough, I'll slam them into princey's rear while he's chasing down my archers".

Nota bene: They might look like knights but they fight like Hobilars. The CHC are distracted from killing my infantry for all of, ooh, four seconds before he sends them fleeing for their lives.

End result: Cumans 1 Serbs 0.