From Project: Redcap
A key event in the Order's early history, where the attempt of Tremere, the last remaining Founder, to dominate the Order by declaring himself overlord of the Order in a Grand Tribunal in 850 was halted by the intervention of a mysterious group of Magi in 848.
While Tremere did negotiate peace terms with his Sundering enemies with the intervention of the Primus of House Guernicus, his memories of the event were removed with is consent as part of the agreement, and therefore the architects of the event remain unknown.
The Sundering is described in ArM4 232 and specified to happen in the ninth century, before the corruption of House Tytalus in the tenth century and the Schism War of early eleventh century. It is claimed that its authors are unidentified.