The Celestial-Rakata War was a conflict that occurred millennia before the birth of the Old Republic whose inception and outcome have been lost in time.
Dr. Insmot Bowen, a specialist in pre-Republic history at the Obroan Institute for Archaeology, gave a debriefing in 1 BBY to General Arhul Kurumenga of the Imperial Department of Military Research, Admiral Conan Antonio Motti of the Imperial Navy, and Master of Imperial Projects Bevel Lemelisk relating to various discoveries that would provide hints, albeit minimal, regarding aspects of the Celestials, including their conflict with and eventual defeat at the hands of the Rakata.
Behind the scenesEdit
This war was supposed to have been mentioned in The Essential Guide to Warfare but was cut by Jason Fry. It was eventually unveiled in the Star Wars Blog article Star Wars: The Essential Guide to Warfare: Author's Cut — The Celestials.