The Allegiance-class battlecruiser was similar in appearance to both the Victory, Procursator and Imperial-class Star Destroyers, but was larger than all of them, reaching a length of 2,200 meters. Unlike the Victory and the Imperial, the Allegiance-class lacked ventral hangar bays. Like fellow hangarless models such as the Procursator and Tector-class, the model could seemingly only rely on its own exterior ordnance, as the Allegiance appeared to be unable to carry any starfighters or ground vehicles internally.
The terraced dorsal superstructure that surrounded the Allegiance's bridge tower was far smoother than those on the Imperial-class, allowing for better armor coverage and less exposure of the inter-plate surfaces.
Offensive and defensive systemsEdit
The Allegiance-class was armed with turreted gun batteries in a similar layout to the dorsal turret guns on the Imperial I-class Star Destroyer, albeit with an increased number of guns, six instead of four, due to its larger frame. The ship also had several cannons situated on the mid-axis of the vessel, similar to the batteries located on the mid-axis of the Imperial-class models, as well as 3 similar batteries on each side of the ship.
The Allegiance-class battlecruiser had a visible armored reactor bulge on the ventral side of the superstructure, similar to the Imperial and the Victory-class. Due to scale, it was more massive than on these contemporary Star Destroyers.
The command tower was T-shaped, like the modular towers produced for many Kuat Drive Yards designs. It was put in full view of enemy vessels, which made it an easy target for mass-bombardment by an enemy. The Allegiance's tower included a visible section that stood out from the rest of the tower, similar to the bridge sections on the Imperial II-class Star Destroyer and the Executor-class Star Dreadnought. The tower was capped by geodesic domes, like on other contemporary Imperial warships.
The Allegiance-class was in service with the Imperial Navy by 3 ABY. During a rendezvous with the elite unit Death Squadron, prior to the Battle of Hoth, several Allegiance battlecruisers formed part of a fleet that was observed by Captain Firmus Piett and Death Squadron's commander, Admiral Kendal Ozzel.
In service, the Allegiance was known as a "Heavy Star Destroyer" and was noted as being typical of the kind of ship that fit the "Star Cruiser" designation of warship. Due to its size, power and combat focus, the class was afforded the designation of "battlecruiser" by the Republic Navy War College at Anaxes, using their warship classification system. "Star Cruiser", on the other hand, was recognized only by some military historians as a designation for smaller models of battlecruisers. The distinction was used by some to separate ships like the Allegiance from larger battlecruiser models like the Praetor Mark II.
At some point during the time of the Galactic Empire, at least three ships of this class were serviced at the massive Naval Station Validusia in the Validusia system. The system was located in the Expansion Region and its Imperial facilities could maintain several heavy Imperial warships at once, including both Star Destroyers, battlecruisers like the Allegiance and large dreadnoughts and fleet replenishment ships.
The Dark EmpireEdit
Allegiance-class battlecruisers were pressed into numerous duties during the time of Emperor Palpatine's return, including escort duty for even larger command ships and providing protection and support for Palpatine's defense forces at Byss, as part of the Byss Security Zone. They were used throughout the Beshqek system to patrol and monitor traffic to and from the secluded throne-world and worked in conjunction with Gauntlet Scanner Stations, destroying any ships the stations identified as hostile. During this phase of its career, serving in the navy of the Dark Empire, the Allegiance-class was sometimes referred to as "Imperial-class" and a "Super Star Destroyer" by New Republic forces.
At the Battle of Calamari in 10 ABY, the battlecruiser Allegiance served as a command and communications ship for the invasion fleet at Dac and transmitted images back to the command center at Byss. A New Republic task force picked up the transmissions while in hyperspace transit to the system and homed in on their origin. As the fleet jumped out of hyperspace, General Lando Calrissian ordered all ships to fire from his flagship, the Emancipator. The fleet bombarded the Imperial battlecruiser and its Procursator-class escorts and destroyed both the Allegiance and the Star Destroyers. Following the strike, Calrissian's fleet passed by the wreckage of the Allegiance and began landing their airspeeder reinforcements.
Following the Republic victory at Dac, two Allegiance battlecruisers escorted Palpatine's flagship, the dreadnought Eclipse, as it traveled to the Cyax system to confront the New Republic leaders. Ships of the class later participated in the Battle of the Emperor's Citadel, the failed attempt by a Republic strike team to infiltrate Byss and topple Palpatine.
End of serviceEdit
By the time following the Second Galactic Civil War, any ships of the Allegiance-class had presumably all been destroyed or retired, as both the Galactic Federation of Free Alliances and the Fel Empire put their naval focus on smaller, lighter designs and no major powers in the galaxy used Super Star Destroyers anymore due to their expensive upkeep.