(covers information from several alternate timelines)
The following is a list of unnamed Negh'Var warships.
By commander
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By year
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Attack on the USS Pasteur
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Two attack cruisers
In an alternate future, two cruisers attacked the USS Pasteur while in the Devron system. The crew of the Pasteur was saved by the USS Enterprise-D, after destroying one of the Klingon vessels. (TNG: "All Good Things...")
Attack on SC-4
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In an alternate 2404, two warships were used at Korath's disposal. They were used to attack Vice admiral Janeway's shuttle, SC-4, but did no damage to the shuttle's ablative armor, and the shuttle escaped.
Later, two of these warships decloaked and began firing on on Janeway's shuttle. She tried to deploy the ablative armor, but it had been knocked off-line. She urgently hailed the USS Rhode Island, informing Captain Kim of her situation. The Rhode Island returned and warded off the warships long enough for Janeway to use the chrono deflector she stole from Korath to generate a temporal rift. After emerging in the past, Admiral Janeway convinced the USS Voyager to prevent Korath's warships from reaching 2378 by sealing the rift with an anti-tachyon pulse. (VOY: "Endgame")