The Planar Wars is an event held to have occurred between 4600 and 4700 of the Lezarian calendar. The real extent of it is unknown, due to various temporal discrepancies that took place during the time period, so it is arbitrarily held to have taken place between those years.
The war began when hostilities erupted between Whitefire, Darkhammer, Tempest, and Conclave. The Watchers were also involved, whether they wanted to be or not, but attempted to remain neutral observers. It is unknown what precisely started the war, but tensions between the factions had been high for centuries.
However, the Planar Wars would have merely been another conflict if it had not been for the creation of the Wheel of Chaos. Harmony, with the assistance of thirteen Soul Mages, forged the Wheel out of soul matter. When it spun, it began to unravel the fabric of reality. The Veil between the Material Plane and the Ethereal Plane weakened and collapsed, drawing a large section of the universe into an increasingly chaotic, unstable mass.
The Planar Wars finally came to an end when Sharina Kell, who, due to nonlinear rebirths had been forced to live through the events twice, managed to contact Suzcecoz, Keolah, and Hawthorne. The three of them used the Zarnith to break the Wheel of Chaos, and slowly began to restore order to the universe.