The Battle of Eredenn unfolded when Separatist General Sev'rance Tann made her way to the planet during the Hunt for the Decimator. She had discovered the existence of the weapon from Boorka the Hutt.
Acting on Count Dooku's orders, Tann's forces swiftly eliminated the clone trooper garrison present and seized the research installations involved in developing the Decimators. Wookiee reinforcements from the Eredenn Prime contingent arrived subsequently, but were unable to rescue the clones, with half their forces being defeated by the CIS. Regardless, their actions served as a diversion, facilitating the escape of clone troopers to Alaris Prime along with the operational codes necessary for the Decimators.
She acquired the war machines and secured a protocol droid carrying data related to the Decimator. Consequently, Sev'rance Tann progressed one step closer to gaining control of the Decimator.
