After I got the information I wanted, I had the male prisoners join the goblins and play a game to improve their commanding power.
It was an actual warfare strategy game where the players with the title of captain had to keep their pawns, that were equally distributed amongst them, under their thumb and crush the pawns of the opponent by giving orders to their own.
The pawns were equipped with wooden swords and shields, a bow, an axe, a spear or with just a shield by itself. The point was to give commands that suited the equipment of the grunts.