O'paal was the Empire's military hub along the Tarkin Corridor, with Orbital Station Guardian its most prominent feature. Guardian, which was an Imperial military academy, naval port, Imperial Army barracks and headquarters for Naval High Command, was chosen as the first target in the New Republic's counterattack utilizing Rebellion-era tactics. The Empire had removed a large portion of O'paal's defense fleet away from O'paal, with the Empire preparing for the final push at Coruscant and Cochran, thus leaving Guardian with a token defense force.