The Eighth Imperial Fleet was once a renegade element of the Galactic Empire, but now forms a large part of the military forces of Malphuus's Imperial Union.
The fleet was a proud part of the New Order under the command of Vice Admiral Steele. It started its life patrolling parts of the Outer Rim before being moved to the Core in the Year 44, in response to increasing rebel activity, specifically in the Bormea and Darpa Sectors. During this time it was infamously responsible for the Eldor Massacre.
Elements of the fleet were present at the Battle of Endor, but when the Death Star was destroyed, Steele ordered his forces to withdraw. During the confusion in the month that followed, he assembled his fleet at Iridonia and set out into the Unknown Regions, claiming to be following orders to pacify the region given to him by Emperor Palpatine before his death.
In truth, there were no such orders. Steele had long held ambitions of power, and revealed to only his most trusted officers that he intended to carve his own Empire. Promoting himself to High Admiral, Steele began conquering worlds in the Unknown Regions.
He soon encountered the most coreward of the Goa'uld System Lords, a minor power named Sobek. The fleet battled Sobek for over six years, the Imperials boasting superior firepower and tactics, yet suffering from a severe lack of resources.
Risking running out of supplies completely, Steele went to Sobek with a peace proposal, taking with him his trump card - schematics for the Super-class Star Destroyer, a weapon which could turn the balance of power amongst the Goa'uld in Sobek's favour. Construction began immediately over Faiyum, and the Fleet was able to take advantage of Sobek's considerable industrial strength to begin replenishing itself.
The alliance was believed smashed after the destruction of the Star Destroyer, but the fleet was found working with Sobek's forces once again. It is now known that Sobek did not perish with the Star Destroyer, but escaped and took Steele as a host. In this guise, he led both his own forces, and those of the Eighth Imperial Fleet.
Armed with their Deity-class Star Destroyers, the fleet tried to invade the Imperial Remnant, but was prevented from doing so by New Republic intervention.
After the capture of Sobek, the clone Malphuus took control of both forces and integrated them into his Imperial Union.