The aforementioned scenario states: “Fight with Bohemond for rewards”
As far as I can tell, nothing really happens no matter how long you attack something with your hero unit (at least on hard difficulty). Before reporting this as a bug, does someone know what is supposed to happen here?
The 6th hint suggests that “more Normans will join him” the more that he fights, but there only seems a single instance of receiving additional reinforcements in the scenario.