The Silencer was attached to the front of the Dreadnaught so that it could be fired up quickly.
The Doombringer fought for the Sith Empire in the Cold War under the command of Moff Valion Pyron and was chosen to be the first Imperial Dreadnaught to test the Silencer, a powerful superlaser built by the Empire which was able to wipe out an entire fleet. The Sith Lord Kallig visited the Doombringer to see the superlaser's power itself, hoping that the demonstration could help gather allies in the Empire. After the Silencer destroyed an entire Republic Fleet, Kallig ordered that all the Dreadnaughts under command of their allies to be equipped with one Silencer Superlaser.
The Doombringer shares characteristics with the Conqueror, an Imperial-class Star Destroyer during the Galactic Civil War who was equipped with a superlaser similar to that of the Death Star.