The USS Valdemar was an Ambassador class heavy cruiser that served in the Sixth Fleet during the Dominion War. She served as the entire fleet's flagship for Fleet Admiral Robert Skinner and was commanded by Fleet Captain Cherok ch'D'Arv.
The starship was named for Valdemar Pouslen, inventor of the first tape recorder.
In 2372 she was at Andoria for a change of command ceremony, where Captain Cherok ch'D'Arv became her new commander. Crew members from the Lionheart, Midway and San Marino attended the ceremony. ("Andorian Christmas")
Prior to the assault on the Torros III Shipyard, the vessel rendezvoused with the armada from the Typhon Sector in order for Fleet Admiral Robert Skinner and his staff to come aboard in the Osreo System. The USS Centaur and USS Majestic transported command officers from the Second Fleet to the heavy cruiser for a meeting prior to the raid. ("Declaration")
During Operation Return the ship's starboard nacelle and navigational deflector were badly damaged during a strafing run by a pair of Cardassian fighter craft.
After the retaking of Deep Space Nine and the Bajoran System from Dominion forces, a meeting of all wing, tactical wing and Fleet Captains was held aboard the Valdemar while in orbit of Prophet's Landing. After the meeting, the ship headed for Starbase 375 for repairs.After the Dominion War, the Valdemar was replaced as the Sixth Fleet's flagship by the USS Merryweather and the heavy cruiser went into drydock at the San Fransisco Fleet Yards for a refit. A new bridge module, quantum torpedoes, metaphasic shields, enlarged shuttlebay and a class 8/0 warp engine were among its upgrades.