Yes, it is based on my current campaign. I had the Emperor and his sons trapped in Serbia. In a very hard fought battle a killed most of his army, and managed to capture the rest as it routed off the field. Only he escaped. So the next year I assaulted the castle. I had a units of Mongrel infantry attack the gate, then charge him. They routed (most likely because they were down to 4 out of 60 men) and he chased them out to my arbalesters.