Krell's battle cruiser was a Klingon D5-class battle cruiser in service during the 2150s. In 2154, the battle cruiser, under the command of Admiral Krell, was dispatched to destroy Qu'Vat Colony to eradicate the Klingon augment virus forged there. The ship was intercepted by Earth Starfleet starships Enterprise and Columbia in orbit of Qu'Vat, provoking a battle that also involved two Birds-of-Prey. The battle concluded when a sample of the virus was transported aboard Krell's cruiser, infecting the ship's crew until an antidote could be delivered. (ENT: "Divergence")