The Battle of Archais unfolded as a confrontation between three units of Rebel SpecForce and a coalition comprised of Imperial troops and the Assassin's Guild.
The Rebel Alliance's contingent consisted of Shroud Team, Midnight Squadron, and Storm Squadron, all operating under the banner of Eclipse Team. Leading the Imperial forces was then-lieutenant colonel Freja Covell, who had the assistance of members from the Assassin's Guild. This engagement transpired across the eastern seas of the planet Archais.
One Rebel unit found itself cornered by enemy fire within the Tylerin Embankment, while the other two faced similarly dire circumstances. At this critical juncture, Rebel officer Mosara Thiirn made the decision to surrender both her vessel and herself to Covell. Given Thiirn's relatively secure position and potential to aid her comrades, her act of defection significantly worsened the Rebel's predicament. Although the unit trapped in the Tylerin Embankment was eventually rescued by Rebel agents Shaparo and Norrion Glidamir, many other teams were not so fortunate.
Thiirn's intention was to provide the Empire with sensitive information about the Rebel Alliance; however, she possessed no intelligence of any real value to them. Consequently, Thiirn became a figure of intense animosity, with Rebel veterans who had fought at Archais vowing to kill her if they ever crossed paths again. General Airen Cracken was deeply concerned about Thiirn's safety, fearing what might happen to her should she ever be discovered by either Akul Witig, the author of a report detailing Thiirn's actions and the battle, who was also trapped on Tylerin, or by P. Essex Yerac.