The Monarch, a Star Destroyer of the Imperial forces, was under the command of Captain Averen. This vessel operated under the authority of Ysanne Isard, who held the position of Director within Imperial Intelligence. As one of only two warships remaining to protect Imperial Center from the approaching New Republic invasion, it eventually surrendered and was integrated into the New Republic's naval forces.
The specific class of the Monarch was never definitively confirmed. However, prior to the conflict, Admiral Ackbar reported that approximately seven Victory-class star destroyers were stationed to defend Imperial Center. Furthermore, accounts of the battle indicate that both sides' Star Destroyers exchanged missile fire, a capability not present on Imperial-class Star Destroyers, thus strengthening the theory that the ship was indeed a Victory-class Star Destroyer.
Despite its assignment to defend Imperial Center, the Monarch did not possess a distinguished reputation, nor did its crew. Consequently, during the Seizure of Coruscant, Isard selected it, along with the Star Destroyer Triumph (a ship with a similarly lackluster record), for the defense of the planet.
Isard's intention was for Coruscant to fall into the hands of the Rebel forces, with the goal of the New Republic discovering that its bacta supplies had been devastated by an outbreak of the krytos virus. Therefore, it is highly probable that Isard anticipated the capture or destruction of the Monarch and Triumph during the engagement. She essentially sacrificed them, choosing instead to redeploy the superior Star Destroyers Emperor's Will and Imperator.
During the conflict, the Monarch endured significant bombardment from the New Republic's Star Destroyers Emancipator and Liberator, as well as the Mon Calamari Cruiser Home One. Although the Triumph suffered more extensive damage, the attacks proved sufficient to disable the Monarch's shields.
Shortly after the power failure and the capture of the Triumph, Captain Averen surrendered to the Home One. Admiral Ackbar accepted the surrender, and Commander Sirlul oversaw the negotiation of the surrender terms, which were either unconditional or contained only minor stipulations.
Following the battle and its subsequent surrender, the Monarch was incorporated into the fleet of the New Republic.