In the Battle of Marchford the fifteenth legion came into conflict with a demon that was harbored in a temple and later released by the Heiress, Akua Sahelian.
The remainder of the Silver Spears along with villagers and animals who were corrupted by the demon's influence stormed Marchford.
The fifteenth legion used goblinfire and urban warfare to direct the battle and defeat the devils. The corrupted Silver Spears attacked with the demon and only a whole group of Named could stop them.
While the battle itself was a victory, the true danger of demons is their influence as all corrupted soldiers had to be killed after the battle.