I had a weird one a few nights ago in my Danish/Early/Hard campaign. I had invaded Scotland, and pushed the English off the British Isles (left with only Normandy, IIRC). I had not yet taken Wessex, they had rebelled when I killed the English King in Wales the turn before. So Wessex had 2 units of Royal Knights, just ripe for the slaughter, and I moved in with my 6* general with some Vikings/Clansmen/Feudal Sergeants, maybe 4-500 troops total.

Of course, the French decided to join the party from Flanders. We weren't at war (no alliance though), so I wasn't really sure what was going to happen. They also outnumbered me, and I didn't really want them to get the province that way. I got a bridge map, with the French on my side and to the left, and the rebels on the other side of the bridge. I set most of my troops facing the French, with a Viking and FS unit facing the bridge in case the rebels got frisky. The rebels stayed where they were, and the French moved forward, sort of angling towards the bridge. But then they tooted their horns and charged in. They had a few units of hobilars, some militia and spears, and two RKs. After some fighting and dying, they started to rout. The best part was that they routed across the bridge, right into the rebels on the other side, who proceeded to slaughter them to a man. This also drew the rebels across the bridge to my side, where I was able to crush them more efficiently. Couldn't have asked for a better result. Not only did I take Wessex, but the French wasted a stack and took the blame for starting the war that I wanted anyway. They didn't even get the chance to attack my ships that turn, and I was able to prepare for it on the next.