A sector fleet was a type of naval fleet formation that was used by the Galactic Republic, and later the Galactic Empire and the nascent Alliance to Restore the Republic during the Imperial Era.
The Galactic Republic Navy used local sector fleets during the Clone Wars. A sector fleet was active in the Abrion sector, while another sector fleet was active in the Ferra sector.
The Lothal sector fleet in orbit above Lothal.
A sector fleet in the Imperial Navy of the Galactic Empire was a type of naval fleet formation that, together with other Imperial Military and intelligence assets, formed a Sector Group. Sector fleets were allocated to the 1,024 sectors of the galaxy, and could be local naval forces, or could also be a major numbered fleet of the Imperial Navy. The Lothal sector fleet was one such fleet that served as a small anti-smuggling task force under the command of Admiral Kassius Konstantine, and blockaded the sector while it hunted insurgents. Its efforts were later considered inadequate by Governor Arihnda Pryce, who requested that the Imperial Seventh Fleet reinforce the Empire in the sector. The Lothal sector fleet consisted of six Imperial I-class Star Destroyers including the flagship Relentless, and two Arquitens-class command cruisers.
The Anoat sector fleet was another local sector fleet that operated in the Anoat sector under the command of Governor Ubrik Adelhard. It consisted of a number of Imperial II-class Star Destroyers including the flagship Dread Omen. It later served as the naval forces of the Imperial remnant of Governor Adelhard when the Empire splintered. Local sector fleets could operate outside of their assigned sectors while on certain missions. Additionally, the Imperial Navy maintained at least one major numbered sector fleet, the 14th Sector Fleet.
The Phoenix Cell, an Alliance sector fleet
"The Alliance," the name given by Rebel leader Mon Mothma to the nascent Alliance to Restore the Republic, utilized local rebel cells with naval forces as sector fleets. One such sector fleet was Phoenix Cell, which operated in the Lothal sector and was led by Commander Jun Sato. The Phoenix Cell, at the time it was considered a sector fleet, consisted of the flagship Pelta-class frigate Phoenix Home, five CR90 corvettes, and Phoenix Squadron. It participated on the action at Mustafar in 4 BBY to assist in rescuing the Spectres rebel cell from the Empire.
- Star Wars: The Rebel Files