First Keyblade War

The Keyblade War (キーブレード戦争) was a mysterious conflict in which many Keyblade wielders fought prior to the events of Kingdom Hearts Birth by Sleep. The conflict aroused when Keyblade wielders of Light and Darkness clashed with each other to create the X-Blade. The failed attempts resulted in the scarred remnants that eventually became known as the Keyblade Graveyard. Master Eraqus and Master Xehanort do discuss the events of the Keyblade War, having heard legends of it. It is during this encounter between the two Keyblade masters that Xehanort's goal to unlock the mysteries of what took place at the Keyblade War's end through creating the X-Blade become clear. In order for this to be done, however, Xehanort would need to join two hearts, one of pure light (Ventus) and the other of pure darkness. The one of pure darkness, whom he named Vanitas, would later become his apprentice and seek to open Kingdom Hearts through the X-Blade, thus allowing Keyblade wielders from other worlds to reassemble in the Keyblade Graveyard, starting a second Keyblade War.