Sector Group A Sector Group was a formation of the Imperial Navy , and to some extent the Imperial Army , defined as the total naval strength available to a sector . Command of a Sector Group was delegated to a High Admiral . Usually , " high admiral " was a title granted to the sector Moff ; however , in cases where sector naval forces were constantly engaged in high - intensity operations , the high admiral was a separate position to the Moff to allow the latter to concentrate on running the sector without devoting a disproportionate amount of time on naval matters . History . 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 scrutinized by Coruscant . In addition , the Sector Group was also created as a means to ensure both the Imperial Army and Imperial Navy could work together on a common goal , due to the jurisdictions under the Old Republic making it impossible for the Republic Army and Navy , respectively , working together . Organization . The early Sector Groups were drawn largely from the old Planetary Security Forces , nationalized in the final days of the Galactic Republic . Sector Group HQ included a squadron under the personal command of the Moff , and some Moffs with political connections or proven tactical ability sometimes had more squadrons available to them . On average , 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 . The Group ' s combat elements were split between " Superiority " and " Escort " : a superiority fleet was a space - combat force spearheaded by six Star Destroyers , each 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 . Officially , the Sector Group is the largest unit in the Imperial Navy . However , there does exist even larger naval forces to be assembled than Sector Groups known as regional groups or Oversector groups , although these are not considered part of the standard Order of Battle . Additional Sector Group resources outside the combat element included the assault fleet , capable of deploying four entire surface Armies ; the support fleet , used to fulfill 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 . In 10 ABY , New Republic historian Arhul Hextrophon recognized that , owing to Sector Group resources like Super Star Destroyers and Torpedo Spheres , it had been almost impossible for the Rebel Alliance to properly estimate the power of the average Sector Group during the Galactic Civil War . He made this observation in a guest lecture at the Brionelle Memorial Military Academy on Chandrila shortly after the Battle of Calamari .