Sector Fleet The term Sector Fleet was a naval term that enjoyed near - universal currency as a generic term for naval forces at the sector level . History . Origins . Before the Clone Wars , naval task forces known as " fleets " were found in many , if not most , of the thousand or so sectors that comprised the Old Republic . During the years of turmoil that saw the fall of the Republic and the instigation of the New Order , the rapid military buildup was coupled with the ( at least temporary ) creation of far larger territorial sectors . During the Clone Wars , the Grand Army of the Republic was divided into twenty Sector Armies , each with a theater of operations far larger than one traditional sector : the 4th Sector Army , for instance , was the primary GAR command for the entire Outer Rim . Shortly after the Declaration of a New Order , the first Moffs were assigned to govern sectors which were likewise , in at least some instances , significantly larger than those of the Old Republic . What is less clear , however , is exactly how this reorganization impacted on the naval organization of what might be called " Sector Fleets " . Imperial Order of Battle . Despite being an established term , " Sector Fleet " was notably absent from the standard Order of Battle of the Galactic Empire ' s Imperial Navy , which used the term Sector Group to denote the entire naval deployment in a sector . The term Fleet was used to indicate important naval formations that were typically deployed within and throughout a sector , but which were not equated with the Sector Group . In the Empire ' s early years , the size of the Imperial Navy continued to expand rapidly , and the number of Moffs increased dramatically . Eventually , each Moff controlled a sector comparable in size to - and often simply identical with - one of the historic sectors of the Old Republic , within which the total Imperial Navy deployment was known as a Sector Group . The Sector Group level of organization came about somewhat by accident : the Moffs of the Empire ' s sectors , installed under the Sector Governance Decree in the final days of the Republic , complained that the Imperial Navy ' s force requirements in quelling Separatist holdouts routinely robbed their sectors of resources without sufficient consideration for local security needs . Under the Sector Governance Decree , the Moffs held the power of the old Governor - General s to raise forces and began raising their own local militia s . Alarmed by the prospect of local military forces not loyal to Imperial Center , the Admiralty stepped in and created Sector Groups , local forces directly controlled by the Moffs but carefully scrutinised by Coruscant . These Sector Groups were drawn largely from the old Planetary Security Forces , nationalized in the final days of the Republic . A standard Sector Group was composed of 2 , 400 ships , of which 24 were " Imperial " - class star destroyers and an additional 1 , 600 were smaller warships . These Sector Groups were much larger than the fleets assigned to sectors under the Old Republic , though many officers continued to use the term " fleet " for any formation of squadron - size or upwards . When the first Oversectors were created under the Tarkin Doctrine , it was specifically said that multiple Sector Groups were to be assigned to each of them . The Imperial Order of Battle , meanwhile , restricted the term Fleet to a class of large formations with responsibilities spread across an entire sector , but subordinate to the Sector Group command hierarchy . Reflecting this subordination , these Fleets were commanded by Fleet Admirals , answerable to the High Admiral in command of the Sector Group - who was often the Moff himself . There was no hard and fast system of organization for the types and numbers of Fleets under a Sector Group ' s command . However , the Group ' s combat elements were split between " Superiority " and " Escort " : a superiority fleet was a space - combat force spearheaded by six Star Destroyers and nominally accompanied by a battle squadron of eighteen smaller ships ; escort fleets , meanwhile , were composed of force escort s and were designated for combat against pirates and raiders , which in practice meant that they were the Empire ' s first line of defense , protecting civilian freighters , attacking corsairs ' hideouts , and guarding remote outposts . The ships dominant in escort fleets included old Trade Federation frigates and CR90 corvettes , which in time were replaced by EF76 Nebulon - B escort frigates and escort carrier s . Additional fleets outside the combat element included the assault fleet , capable of deploying four entire surface Armies ; the support fleet , used to fulfil the immense logistical requirements of the Sector Group , the deepdock fleet , which provided repair capability ; and the bombard fleet , a rare formation nominally composed of eighteen Torpedo Spheres , used to break down planetary shields in offensive operations ( despite its nominal composition , such fleets were never actually at full strength during the Galactic Civil War as the Empire never constructed more than six Torpedo Spheres ) . One thing that is unclear is whether any fleets existed that were not part of the Sector Group hierarchy . It is known that a number of the Empire ' s most powerful battle fleets were assigned to specific sectors : for instance , Azure Hammer Command , the primary fleet guarding the Core , was the Sector Fleet for " Sector One " , the Imperial Center Oversector , while Admiral Zsinj ' s fleet in Quelii sector , tasked with pursuing the war against the Drackmarian s , was said to be the most powerful single fleet in the Empire . It is hard to find any categorical examples of Imperial forces that operated outside the Sector hierarchy . It is known that ten percent of the Navy ' s ships were said to be kept in reserve in the Core ready to deploy against threats anywhere in the Galaxy ; but such deployments could easily be accomplished by assigning them from one Sector Group to another . Later Developments . After the Battle of Endor , the collapse of Imperial authority and the New Republic ' s disinclination to maintain a federally - controlled military presence in most sectors saw many sectors acquire autonomous " Sector Fleets " answerable to local leaders ; at the same time , the term Sector Fleet began to be used with more regularity in the Empire , largely eclipsing old terms like Sector Group and Superiority Fleet . In " Cracken ' s Threat Dossier " , it was stated that each of the New Republic Defense Force ' s five fleets were the size of an augmented Sector Group . By around 19 ABY , it is known that Imperial officers regularly used the term " Sector Fleet " to describe forces built around the Star Destroyers operating in a sector - of which there were now typically around a dozen under each Moff ; although answerable directly to the Moff of the relevant sector , the Supreme Commander could call on these ships to reinforce the Imperial Starfleet proper , as was done during the Yuuzhan Vong War . On present evidence , however , many aspects of the this new Imperial usage of the term " Sector Fleet " remain unclear . It is not known what precise relationship a " Sector Fleet " bore to the old Superiority Fleets and Sector Groups , nor is it clear whether the background to the emergence of the term was an organized process of reorganization and redesignation throughout the remaining sectors of Imperial space , or an " ad hoc " response to the chaos into which Imperial forces had been thrown over the decades since Endor . Also , it should be noted that there seem to have been a further hundred or so Star Destroyers available to the Supreme Commander additional to the ships of the eight Sector Fleets , but no evidence is available to indicate how these ships were organized .