In the dark mirror universe, the Imperial Starfleet was the main military arm of the Terran Empire during the 22nd and 28th centuries. Like its primary universe counterpart, the Imperial Starfleet was controlled by a group of admirals, but was overseen by a grand admiral who served as Commander-in-Chief of the Imperial Starfleet. The commander in chief was in turn answerable to the Emperor of the Terran Empire.