War of the Seventeen (Lorica)

The War of the Seventeen
The sects of the Concord, standing united, waged a war against the priests of Luminarism, using their own primitive form of magic against the much more advanced magic of the priests, who though they nominally persecuted everyone who used magic, used plenty of it themselves. This hypocrisy became ever more evident to the soldiers in the war as the Order of Concord, pooling their numbers, was able to force the mage-priests into a series of pitted battles where they were forced to use their magic where all could see them. As a result, even as the mage-priests won practically all their battles, each battle resulted in more and more people throughout Ethaya becoming disillusioned with Luminarism, soldiers telling any civilian who'd care to listen, about the magic spells unleashed by the priests of anti-magic. So so though the mage-priests won their battles, they lost the war, and religion in Ethaya became replaced with a moderate, magic-accepting denomination of Luminarism, which still exists in its weakened form in Ethaya to this day.

While this war is called the War of the Seventeen, it started with seventeen sects united in a Concord against the priests and ended with twenty-nine sects; three sects had been utterly destroyed by the mage-priests and their devout, but another fifteen had joined, having seen the usefulness of being united against a common foe.