The Cathleen, a Mon Calamari Star Cruiser of the MC80 Liberty type, served the Alliance to Restore the Republic throughout the duration of the Galactic Civil War.
Prior to the Battle of Yavin, the Cathleen was observed awaiting the return of starfighters and shuttles that were battle-damaged. These craft belonged to Blue and Gold squadrons, and had just concluded a successful strike against Imperial shipping within the Corporate Sector. The Imperial Nebulon-B frigate known as Terminator then appeared, launching TIE Bombers with the intention of eliminating the exposed Rebel vessels. Red Squadron, consisting of two X-wings and two A-wings, engaged the Imperial fighters, giving the Cathleen enough time to recover the other Rebel ships and jump to safety. This event was later used as a training simulation for new pilots.
Shortly after the Battle of Yavin, the Cathleen successfully repelled the Imperial Nebulon-B frigate Sentinel during an engagement in the Hollan D1 sector. Subsequently, it took on captured Alpha-class assault gunboats during Operation Ram's Head. Later on, the Cathleen became the final vessel to evacuate to Hoth, and the Imperial Nebulon-B frigate Dragon attempted to prevent its departure. After combined attacks from the Cathleen and assistance from Red Squadron B-wing starfighters resulted in the frigate's destruction, the Cathleen was then attacked by CR90 corvettes of Fang, a squadron of stormtrooper transports, and ultimately the Star Destroyer designated Maximum. Nevertheless, the Cathleen managed to escape into hyperspace unobserved.