The Imperial Space Force functioned as the substantial space warfare division of the Galactic Empire, and it also served as its leading military component. Initially under the command of the Jedi-Bendu, the personal guardians of the Emperor, control was later seized following the Great Jedi Rebellion by the Knights of the Sith, who supplanted them and systematically eradicated the competing group. Largely composed of Stardestroyers, the armada received support from the numerous ranks of Stormtroopers and the Space Fortress.
The Imperial Space Force, established and overseen by the Jedi-Bendu, a group of bodyguards who had faithfully protected the Emperors for a period spanning at least 100,000 years, had expanded the Galactic Empire's influence from the celestial equator to the Great Rift. However, the Great Jedi Rebellion resulted in a conflict between the Jedi-Bendu and the Emperor, leading to their banishment and pursuit, which in turn facilitated the rise of Cos Dashit to the position of sovereign and the Knights of the Sith taking over as his protectors.
Denouncing the Aquilaean system's status as the only remaining state not under the Galactic Empire's dominion and considering the attempted negotiations with the Aquilaeans futile, the Emperor declared the commencement of his impending campaign against them, which Governor Crispin Hoedaack and General Darth Vader – the true figures of power behind the scenes – would lead, utilizing the Imperial Star Force and the Space Fortress battle station. The ambush and assassination of King Kayos during General Luke Skywalker's audacious attack intimidated the Aquilaean Senators and Queen Breha into advocating for a peaceful resolution and the removal of the old Jedi-Bendu. After the self-destruction of the Hidden Fortress, General Vader tasked Prince Valorum, a Knight of the Sith, with locating and eliminating General Skywalker and his disorganized rebel company, with Stormtroopers and hover tanks also actively searching for the escapees. Eventually, Annikin Starkiller and Princess Leia were apprehended by Imperial forces and taken to the Space Fortress, awaiting execution under General Vader's orders, only to escape with assistance from the disillusioned Prince Valorum. Shortly thereafter, General Skywalker and his assembled Wookiee squadron launched an assault on and crippled the battle station, inflicting a significant setback on the Imperial Space Force and securing the rebels' first major triumph against the Galactic Empire.
The Imperial Space Force is referred to as the Imperial Navy or Imperial Fleet within the released films and the Expanded Universe. Originating from the initial concepts, the formation of the galaxy's primary military organization, the Grand Army of the Republic, by the Jedi, followed by its seizure by the Sith and subsequent conversion into the oppressive Imperial Forces, is depicted in Episode II and Episode III.