After fleeing before Shiz’s army, Coriantumr’s army are finally driven to a location where they must make a stand, and they fought with a vengeance that caused enough destruction among Shiz’s armies that it was Shiz’s turn to retreat. As they retreat, they apparently kill any of the people they meet who will not join their army. That is a level of destruction against non-combatants that confirms that we are to see them as the worse of the two armies, though neither was considered righteous.