Most memorable battle so far:

I had taken the Citadel of Steffan form the Danes, and they were moving up an army from the south to retake it. One of my other armies met them near the river that flows SW of Steffan, while two units of knights inside Steffan rode out to reinforce me.

On the battle map, the river seperated my Spanish troops and the Danes, with only a small, shallow bed for a crossing. The Danes, predictably, lined up on the other side of the river, and, with their large regiments of crossbowmen, waited for my army to cross. It was Utah Beach. I tested this by sending across a unit of Alumghavars, and they were shot dead before getting close (you cannot maneuver them inside the riverbed).

What about those knights from Steffan? They appeared on the other side of the map from me, hidden in the trees far behind the Danes. The knights crept up, and crept close, until their presence was detected as they approached the enemy rear! Though I lost the opportunity to sodomize them, the Danes still split their forces to meet the new threat.

Which was of course all the opening I needed to dash my army across the river and mop them up.

I've got another one where three Egyptian armies pinched my crusader stack outside Jerusalem. But, it seems everbody has fought that battle so why bother?