USS Defiant (NCC-1764)

The USS Defiant (registry: NCC-1764) was a Constitution class Federation starship that was pivotal in the rise of the First Terran Empire of the mirror universe.

History
Built as part of a fleet of Constitution class starships launched by the Federation in the 23rd Century, the Defiant was lost sometime in 2268 after it fell prey to a false-distress call transmitted from Tholian space. The Defiant was caught in an interphasic rift created by the Tholians, during which the crew went insane from "sensory distortions" and killed themselves. The USS Enterprise was sent three weeks later to rescue the Defiant, but it barely escaped with its own crew intact and the Defiant was declared "lost."

Mirror Universe
When the Defiant disappeared, it reappeared in the 22nd Century of the mirror universe. It was then captured by the Tholians who used slave-labor to strip the ship down and take what information they could in order to use it against the Terran Empire. Their plans were foiled when Jonathan Archer led the ISS Enterprise (NX-01) to Tholian space to take the Defiant as their own. Though the Tholians destroyed the ISS Enterprise (NX-01), they were destroyed by the Defiant, which was liberated by Archer and the survivors of Enterprise.

Some time later, the Defiant engaged the non-Terran rebels in battle, obliterating them in open combat. Later, it destroyed the ISS Avenger to eradicate the Empire of all traitorous thoughts. But Archer died of poisoning shortly thereafter, while the Defiant was en route to Earth. When it arrived, Hoshi Sato, communications officer of the ISS Enterprise (NX-01), declared herself empress and used the Defiant as leverage to finalize her claim.

Shortly thereafter, she led the Terran fleet to Romulus, where the Defiant obliterated the planet and most of its inhabitants who didn't kill themselves.

The whereabouts of the Defiant after that are unknown.