The War of Chains
The War of Chains was not a battle of literal chains.
Around P.A. 250 In the first century since the Awakening, conflict with the Hobgoblins had risen to open warfare yet again. Only this time, each side had magic.
Hobgoblin mystics had learned how to bind spirits and reanimate corpses, forcing the dead of both sides to continue fighting for their new masters. They also succeeded in turning prisoners of both sides into hideous monstrosities bred for combat.
The Illyricans, faced with an army of skilled hobgoblins and hordes of dead, resorted to using a form of mind magic in tandem with unearthed relics. The Battleminds, as they were called, allowed Human and Dwarven to inhabit the minds of peasants, fighting with years of practice and skill without risking their own lives. Most of these peasants submitted to the process willingly, but as the war churned onwards, many more were forced into servitude and combat.
The war itself began and ended in a single year, but its atrocities were remembered for hundreds more. The Empire has since banned raising the dead as well as influencing the minds of others.