A Sector Group represented a specific organization within both the Imperial Navy and, to a degree, the Imperial Army. It encompassed the total naval assets allocated to a particular sector. The responsibility of commanding a Sector Group was entrusted to a High Admiral. Typically, the designation of "high admiral" was bestowed upon the sector's Moff. However, in situations where the sector's naval forces were consistently engaged in intense operational activities, the role of high admiral was separated from that of the Moff. This allowed the Moff to prioritize the administration of the sector without being excessively burdened by naval affairs.
The establishment of the Sector Group organizational structure emerged somewhat unexpectedly. The Moffs governing the Empire's sectors, appointed under the Sector Governance Decree during the Republic's final period, voiced concerns that the Imperial Navy's demands for resources to suppress Separatist holdouts frequently depleted their sectors' resources without adequately considering local security needs. Empowered by the Sector Governance Decree, the Moffs, inheriting the authority of the former Governor-Generals, began to establish their own local militias. The Admiralty, concerned about the potential for local military forces lacking allegiance to Imperial Center, intervened by creating Sector Groups. These local forces were under the Moffs' direct command but were subject to close oversight from Coruscant. Furthermore, the Sector Group was conceived as a means to foster collaboration between the Imperial Army and Imperial Navy towards a shared objective. This was intended to overcome the jurisdictional obstacles that had previously hindered cooperation between the Republic Army and Navy during the Old Republic era.
The initial Sector Groups were primarily formed from the remnants of the former Planetary Security Forces, which were nationalized in the waning days of the Galactic Republic. Sector Group Headquarters included a squadron directly commanded by the Moff. Some Moffs, possessing either political influence or demonstrated tactical expertise, sometimes had access to additional squadrons.
On average, a typical Sector Group consisted of 2,400 vessels, including 24 Imperial-class star destroyers and an additional 1,600 smaller warships. The Group's combat capabilities were divided into "Superiority" and "Escort" elements. A superiority fleet was a space-based combat force led by six Star Destroyers, each ideally supported by a battle squadron of eighteen smaller ships. Escort fleets, on the other hand, comprised force escorts and were tasked with combating pirates and raiders. In practice, this meant that they served as the Empire's primary defense, safeguarding civilian freighters, raiding corsair hideouts, and protecting remote outposts. Officially, the Sector Group is recognized as the Imperial Navy's largest standard unit. Nevertheless, larger naval formations, known as regional groups or Oversector groups, could be assembled, although they were not considered part of the standard Order of Battle. The naval strength protecting Kuat was at least equivalent to that of a Sector Group.
Beyond its combat elements, a Sector Group also possessed an assault fleet capable of deploying four entire surface Armies. The support fleet was responsible for fulfilling the Sector Group's extensive logistical demands. The deepdock fleet provided repair capabilities. Finally, the bombard fleet, a relatively uncommon formation typically consisting of eighteen Torpedo Spheres, was employed to disable planetary shields during offensive operations.
In 10 ABY, New Republic historian Arhul Hextrophon noted that the presence of Sector Group assets such as Super Star Destroyers and Torpedo Spheres made it exceedingly difficult for the Rebel Alliance to accurately assess the strength of a typical Sector Group during the Galactic Civil War. He shared this insight during a guest lecture at the Brionelle Memorial Military Academy on Chandrila shortly after the Battle of Calamari.
- The Star Wars Sourcebook (as Territorial Fleet)
- Imperial Sourcebook
- Death Star Technical Companion
- Galaxy Guide 9: Fragments from the Rim
- Han Solo and the Corporate Sector Sourcebook
- Death Star Technical Companion, Second Edition
- Star Wars Miniatures Battles Companion
- Imperial Sourcebook, Second Edition
- Platt's Starport Guide
- Flashpoint! Brak Sector
- Pirates & Privateers
- Cracken's Threat Dossier
- Star Wars Trilogy Sourcebook, Special Edition (as Regional Fleet and Territorial Fleet)
- The Far Orbit Project
- The Official Star Wars Fact File 11 (STA 3-4: Imperial Star Destroyer)
- Star Wars: Imperial Handbook: A Commander's Guide