The Imperious-class was designed to make use of several especially large thrusters and sported a 'tailfin' similar to those of the Star Destroyers of the Galactic Republic. The class' command bridge was very similar in design to those of most Kuat Drive Yards warships, while spaced in pairs on its sloped superstructure were several towers of unknown purpose.. Compared to the Pellaeon-class, the Imperious-class was larger and more powerful, as well as more efficient in the regulation of its power. It had better shielding to the point that it could take on the full firepower of the Outer Rim Third Fleet before begin to falter, armor, and weapons (which included gravity mines) allowing it to outgun any ship within the Imperial Fleet of Darth Krayt's Galactic Empire. In addition, the Imperious-class could be operated by a smaller crew. Generally, it was to the Pellaeon-class what the Imperial II-class Star Destroyer was to the preceding Imperial I-class.
The Imperious-class started life as the answer to Darth Krayt's demand for a new class of warship that could overpower any other warship type used by the enemies of the Empire. Proposed by Moff Rulf Yage, head of the Imperial Navy, the project was turned over to the engineers and designers of the Mon Calamari Shipyards, who were tasked with creating a new warship that was an overall improvement of the successful Pellaeon-class Star Destroyer. As such, the Imperious-class was ironically a Mon Calamari design, despite being built for the Empire.
Soon enough, a prototype was constructed at the Mon Calamari Shipyards, but in 137 ABY, before it could embark on its maiden voyage, it was used as bait for Galactic Alliance Admiral Gar Stazi and his remnant forces. Imperial Admiral Dru Valan of the Outer Rim Third Fleet attempted to trap Stazi and his fleet, but Stazi's fleet was able to escape with the Imperious.
Masters Sigel Dare and Treis Sinde of the Empire-in-exile Imperial Knights had planted explosives on the ship, meant to activate once the weapons-systems came online, long before the ship was hijacked by the Alliance. When Admiral Stazi became aware of the danger, the explosives were removed, and the two governments began discussing an alliance again. The ship was rechristened the Alliance by Stazi to symbolize the one thing the Sith feared the most.
Despite the loss of the prototype, the damage to the shipyards that built it, as well as their subsequent shutdown following the Sith's extermination of the Mon Calamari, Krayt ordered the construction of more Imperious-class vessels before his demise.
At least one other Imperious-class vessel was fielded. The Darklight was sent to subjugate Falleen in 138 ABY. The ship was lost when it was infiltrated and sabotaged by Cade Skywalker and Wolf Sazen.