The upheaval of 2154 in which the recovery of the Kir'Shara, holding Surak's original teachings, toppled the Vulcan High Command and reshaped Vulcan society.
The Vulcan Reformation was a political and spiritual transformation of Vulcan society in 2154. For years the Vulcan High Command had grown militaristic and secretive under Administrator V'Las, who persecuted the Syrrannites, a group devoted to a purer reading of the philosopher Surak.
In the episodes The Forge, Awakening and Kir'Shara, a bombing of the United Earth embassy on Vulcan is blamed on the Syrrannites. Jonathan Archer and T'Pol travel into the desert known as the Forge, where Archer receives the katra of the Syrrannite leader Syrran, which carries Surak's memories. Guided by it, Archer, T'Pol and T'Pau find the Kir'Shara, an artefact containing Surak's original writings. Meanwhile V'Las provokes a confrontation with the Andorians, and Enterprise places itself between the two fleets.
When the Kir'Shara is revealed, V'Las is exposed as an agent working with the Romulans, and the High Command is dissolved. The reform brought Vulcan closer to the philosophy seen in later centuries, eased tension with Earth and helped pave the way toward the Federation.