In 2155, the Imperator was under the command of Captain A.G. Robinson, and was one of seven ships that attempted to defend Earth from an attack by Empress Hoshi Sato aboard the USS Defiant. The Imperator was crippled in the battle, and the crew subsequently pledged their loyalty to Empress Sato. The ship was later part of the fleet sent to find Empress Sato after she was kidnapped by rebel forces. (ENT - Mirror Universe novel: Age of the Empress)