Just after the turn of the first millennium, open conflict broke out within the Order of Hermes, a prolonged series of conflicts, battles, and assassinations that have come to be known as the Schism War.
Due to the corruption of House Tytalus by diabolists, some within the Order wanted to restrict the interaction among the houses. In their paranoia they felt that this would prevent corruption in one house from leading to the downfall of others. Intrigue, competition, and skirmishes escalated tensions and added to an atmosphere of distrust that began to dominate the Order. Differences of opinion led to frequent wizard's wars and raids against covenant resources.
The confusion thus bred led to an open conflagration as old feuds were sparked anew and recent disagreement grow into open hatred. Some houses became insular and retreated into hiding, while others became increasingly violent to deter potential attackers or to resolve personal grudges. The quaesitorius lost effective control as the magi all but stopped obeying their orders. Sides shifted continually and chaos threatened to consume the Order.
Amidst this anarchy, House Tremere declared war on House Díedne, descendants of the ancient Druids, which had always remained distant from the other Houses and was generally distrusted. Tremere’s primus, Cercistum, called on House Flambeau to help rid the Order of these Druids and their exotic traditions. Always ready for a fight, House Flambeau joined in the battle with relish.
The Quaesitores, seeing a chance to regain power, backed House Tremere and declared House Díedne renounced. Most of the other Houses retreated for safety, but many individual magi with grudges to settle joined in the assault. The ensuing conflict utterly destroyed House Diedne; its last living member was seen in A.D. 1012, though the leaders of the house were not killed and were never found.
With the Schism War over, the Quaesitores insisted on settling all remaining disputes peacefully. Once the smoke had cleared and the devastation that had been brought on by the Schism War became apparent, most magi were eager to stop fighting.
It is whispered in some circles that the entire Schism War and the rumored diabolism of House Diedne had all been a fabrication of Prima Cercistum and House Tremere. Although the casualties suffered by house Tremere were extreme, their service and sacrifice during the conflict had earned them the respect and trust of many within the Order.