The Chaos Crusades

The Chaos Crusades were a war against an incursion of Chaos into the world through unknown means that occurred about a hundred years after the fall of The Old Empire.  The Great Church rallied its forces to stop it and were able to drive the forces of Chaos back through the breach, securing the safety of Europa.

Due to the incursion, the Ardor of Law at the time decided that surely the Chaos was brought to our world through the use of arcane magic, leading to the banning of the Forbidden Arts and formation of the Inquisitors.