This dreadnought was 12 kilometers long, but did not represent the final version of the planned SSD design. It had one main power core located within. Upon completion, it would have been heavily armed.
Code-named the Sarlacc Project, the vessel was designed by engineers on Coruscant and built in orbit of Byss. It was meant to ultimately serve as the flagship of the Imperial Navy, but would never see completion, as it was attacked and destroyed by a strike force of early rebels, pirates and smugglers amassed by the Alderaanian noble Lady Alya Aldrete.
After having disabled the shipyard's defenses, the pilots flew through its unfinished interior, blew up the power core and escaped. Many worlds learned of the rebels' triumph and this event would be one of many to inspire the formation of the Alliance to Restore the Republic.
As it was the largest vessel built by the Empire at the time, it took some time before its successor, the Executor, was begun, due to the resource-extensive construction. Its destruction allowed burgeoning Rebel groups to face off against only lesser ships, and allowed them time to build up fleets of their own.