Get some people for your army in chapter two on the way to the monastary. Enter the monastery and talk to a worried abbot. Remove the two monks he foists on you, heal if you need to, and then leave. Wait a short while beside the road and keep your eye on the approaching mercenary band (black and white herald). Wait until they have entered and exited the monastery (happens very fast) and then attack them. If you win, go back to the monastery and the now angry abbot. Tell him you defeated the gang but didn't find any loot.