The Defender Fleet was an Alliance fleet of close to two hundred warships of mixed classes, based out of Unity Alternate. The fleet was nearly entirely automated, with only admiral Bloch and a small group of officers acting as supervisors. Because of this high level of automation, the ships of the Defender Fleet lacked the numerous facilities needed for Human crew members and instead mounted more weapons, engines and shields compared to their Alliance Fleet counterparts.
The Defender Fleet was created following the end of the Alliance-Syndicate War, and built from the hulls of ships partially completed at the end of the war, as well as new construction at secret docks at Unity Alternate. Largely automated, the fleet was ultimately controlled by an artificial intelligence initially programmed to counter the tactics used by Admiral John Geary.