The Klingon battle cruiser formed the backbone of the Klingon Defense Force for decades. The D7-type vessel was in service in the 2260s, a design shared with the Romulan Star Empire during the brief alliance between the two powers.
Some 228 meters in overall length, the vessel was equipped with warp drive and phase-disruptor armament. The D7-type vessel was later replaced with the K't'inga-class battle cruiser.
Prior to the Klingon-Federation peace conference on Khitomer, Chancellor Gorkon took the battle cruiser, Kronos One, to rendezvous with Enterprise.