The Viscount's design was worked out after the Black Fleet Crisis when the New Republic military realized the need for more powerful dreadnoughts. By the time it was finished in 25 ABY, so many Super Star Destroyers had been captured by the New Republic, that the government considered halting construction on more ships.[2]
The Viscount herself was meant to be a prototype for the design and was built as a battlecruiser at 3 km in length. The subsequent full-scale vessels were 17 km-long dreadnoughts known as the Bounty and the Krakana.[1]
Originally stationed at Coruscant, the warship was eventually deployed to Mon Calamari, following the reorganization of the New Republic into the Galactic Alliance.
There is some dispute about the length of the Viscount. While the more recent The Essential Guide to Warfare has the length at 3 kilometers, to better fit with the quote in Vector Prime about being nearly twice the size of the Mediator, the model from Star Wars Miniatures: Starship Battles and the entry in Starships of the Galaxy, Saga Edition show the Viscount as a 17 kilometer long ship designed to be equal to various Star Dreadnoughts. While other ships do have a difference between versions, such as the Praetor I-class Star Battlecruiser being 4,000 meters vs the Praetor II-class at 4,800 meters, or the various sizes of Bulwark-class battlecruisers, a 3,000 meter ship does not fit well into the class named for it at 17,000 meters, even as a prototype model.