Minister of War signified the civilian commander-in-chief across the planets of the Five Worlds.
When the Second Galactic Civil War began, Thrackan Sal-Solo, the Head of State for Corellia, took control by removing the existing Minister and announcing himself as the acting Minister of War. It's possible the role was eliminated entirely; following Sal-Solo's demise, Wedge Antilles achieved the title of Supreme Commander of the Corellian forces while Rorf Willems became the Minister of Defense.