Marklin Command Cruisers were operated by the Federation during the Four Years War against the Klingon Empire. The Federation Starfleet had been unprepared for all-out war with the Klingons and required a dedicated command cruiser for coordinating fleet actions against the Klingons.
At the end of the war most Marklin Command Cruisers were kept in operations near major Federation outposts and starbases.
The U.S.S. Xenophon, Captain Garth's ship at the Battle of Axanar was a member of this class.