The conflict known as the Assault on Thyferra took place during the Galactic Civil War. It represented the initial attempt to locate and eliminate Moff Kalast, an Imperial defector.
Imperial troops made planetfall on Thyferra, the world Imperial intelligence had identified as Kalast's refuge. The advance team secured ground to the south of a small Rebel facility, situated within territory controlled by the Rebels for bacta production. A field commander then dispatched a stormtroopers squad to disable Rebel sensors and communication systems. Subsequently, Darth Vader arrived and linked up with the Imperial contingent. The Imperial Army advanced into the hills to the north, only to be caught in an ambush by Rebel forces. Clearly, the Rebels still had functioning sensors, which alerted the base personnel to the Imperial incursion.
The isolated sensor station was destroyed by the strike team. The Imperial force then proceeded eastward and demolished the base's power generator. There, they received reinforcements in the form of TIE Maulers and additional Stormtroopers, gaining the capability to conduct bombing runs utilizing TIE/sa bombers. The army then entered the base, eliminating all personnel and defenses. However, Kalast managed to escape due to the field commander's failings, leading to the officer's execution by Vader. Stormtroopers informed Vader that they had discovered pirate symbols on Rebel weapons during their search for survivors. Consequently, Vader ordered the monitoring of surrounding systems, which eventually led him to Ilum in his pursuit of the pirates aiding the Rebels.
This battle served as the introductory mission for the Imperial campaign in the 2006 video game Star Wars: Empire at War.