The Siege of Relay Station 558 was a brutal engagement during the Galactic Civil War between the forces of the Alliance to Restore the Republic and the Galactic Empire in mid-3 ABY, launched as part of the Empire's Life Day Offensive. Relay Station 558 was a Royce class relay station near the Chin'toka system, which was a former Imperial subspace communication array, until being captured by the Rebel Alliance after the Battle of Chin'toka. The objective of the empire was to recapture the station and use it to garner massive intelligence on the Rebellion's movements.
On the station, less than 200 rebel soldiers were left to guard the station while engineers disabled the communications array's security grids and gather the intelligence required. Because the Rebel hold on the Chin'toka system was so fractured, reinforcing the planet and merely re-supplying it was a massive problem; Imperial attack ships frequently ambushed Federation ships on supply runs.
The Empire surrounded the station, with two Imperial I class Star Destroyers, and frequently boarded the station with contingents of stormtroopers, although were pushed back by well-entrenched rebels each time. However, the Rebel soldiers stationed there were supposed to be relieved after ninety days, however they were left on the station for five months. Among the casualties of the defenders were the contingent's commanding officer, Captain Loomis, leaving command of the troops in the hands of inexperienced Commander Hado Parker. By the time the cloaked starship Defiant arrived on a supply run, 104 of the defending soldiers were killed; most of the others suffering from combat stress and post traumatic stress syndrome. A small contingent of Defiant personnel decided to reinforce the station, bolstering the defenses enough to keep on fighting.
The defenders resolved to make a final stand; mines brought by the supply run would be placed in the usual boarding area, where they would catch the Imperials in a bottleneck. During the final attack, the stormtroopers were caught in the ambush by the mines, but they still had advantage in numbers and stormed the Rebel defenses. Despite being outnumbered, the Rebel forces managed to repel the Imperials, and the station remained in Rebel hands. Following the battle, the Rebellion landed a relief force, including an engineering crew to take care of the communications array.