(covers information from several alternate timelines)
|Owner:||United Federation of Planets|
|USS Defiant trapped in spatial interphase (2268)|
The USS Defiant (NCC-1764) was a Federation Template:ShipClass heavy cruiser that was in service with Starfleet in the mid-23rd century, and one of at least three Federation starships to carry the name.
Final mission and loss
In 2268, the Defiant responded to a distress call in the unexplored Tholian sector claimed by the Tholian Assembly. Shortly after entering the region, the Defiant's crew began experiencing sensory distortion, and insanity quickly spread throughout the ship. The ship's chief medical officer was unable to determine what was happening, and eventually the insanity induced by the phenomenon led the crew to kill each other.
Three weeks later, Starfleet ordered the USS Enterprise to mount a search and rescue mission to locate the Defiant. On stardate 5693.2, the Enterprise located the Defiant, only to find it lost between universes in a space warp. The Enterprise's instruments recorded that space itself was literally breaking up, the result of a previously unknown phenomenon known as a spatial interphase. An Enterprise boarding party beamed aboard the Defiant and discovered signs of mutiny and insanity – the captain's neck was broken and his crew were dead.
At that time, the Defiant was visible in the "prime universe" while in the interphase, then, as a result of a later phaser exchange between the Enterprise and the Tholians, a hole created through the spatial interphase pushing the Defiant to parts unknown, and trapping Captain James T. Kirk between universes. Captain Kirk was eventually saved when the Enterprise, encased in a Tholian web, entered the interphase and, upon utilizing full power, was thrown clear of the region while Kirk was locked in the transporter beam. (TOS: "The Tholian Web")
(coexisting on another dimensional plane)
|Defiant in a Tholian drydock|
The Tholians of the "mirror universe" during the 22nd century, by detonating a tri-cobalt warhead within the gravity well of a dead star, created an interphasic rift and sent the distress call which lured the Defiant from the other side to that universe. Soon after, the Tholians took the Defiant to a drydock built into an asteroid-moon in orbit around a gas giant in the Vintaak system and began a salvage operation. This operation was reported to Commander Jonathan Archer of the ISS Enterprise NX-01 through his contacts shortly thereafter. Archer and the ISS Enterprise were eventually ordered by Admiral Black to investigate. (ENT: "In a Mirror, Darkly")
Arriving in the system, Enterprise was destroyed by a Tholian web shortly after beaming an away team over consisting of Archer, Commander T'Pol, Commander Tucker, and Sergeant Travis Mayweather. They were able to escape by restoring the partially deconstructed Defiant's shields and weapons, and destroyed the drydock.
At first, the Defiant could only reach impulse speeds because a Tholian slavemaster, a Gorn named Slar, had stolen a plasma regulator, one of the key components of the warp engines. After Archer trapped and killed the Gorn, Tucker was able to restore warp drive.
The USS Defiant then rendezvoused with the remnants of a Terran assault fleet still engaged with rebel forces. Two Andorian battle cruisers, one Vulcan Template:ShipType cruiser, and one Tellarite cruiser were disabling the ISS Avenger NX-09. The Defiant easily destroyed all the rebel ships except one Andorian cruiser, which Archer intentionally allowed to escape.
After seeing how Archer had treated the rebel Vulcans, and learning of the existence of the United Federation of Planets in the other universe, T'Pol and Crewman Soval tried to sabotage the Defiant with Doctor Phlox's help. When Phlox disabled main power, the Defiant was left defenseless, and Avenger, commandeered by Soval and other non-Terrans, began firing at her. The Defiant received heavy damage until Tucker was able to stop Phlox and restore main power. Archer then ordered the destruction of Avenger. The Defiant's phasers and photon torpedoes caused heavy damage to Avenger, with the second barrage of photon torpedoes breaching Avenger's warp reactor, destroying the ship with all hands.
The Defiant arrived at Earth, now under the command of the self-proclaimed Empress Hoshi Sato. She ordered Admiral Gardner to surrender and stand by for instructions, or she would open fire on Earth. (ENT: "In a Mirror, Darkly, Part II")
|Starships named Defiant|
|USS Defiant (NCC-1764) • USS Defiant (2370) • USS Defiant (2375)|
|Mirror universe: ISS Defiant|
|USS Ahwahnee • USS Constellation • USS Defiant • USS Eagle • USS Emden • USS Endeavour • USS Enterprise • USS Enterprise-A • USS Excalibur • USS Exeter • USS Hood • USS Intrepid • USS Korolev • USS Lexington • USS Potemkin • NCC-1700 • NCC-1707 • Unnamed|
|Mirror universe: ISS Enterprise|
|Alternate timeline: USS Enterprise|
The USS Defiant was originally named the "USS Scimitar," in an early draft of the script for "The Tholian Web". (Star Trek Compendium, et al.)
The registry number NCC-1764 was originally conceived by Greg Jein in an article in T-Negative from 1973. It was subsequently used by Bjo Trimble in her Star Trek Concordance, FASA, and eventually ended up in Michael and Denise Okuda's Star Trek Encyclopedia, before finally being seen on-screen in "In a Mirror, Darkly" and later in the remastered version of "The Tholian Web".
In the final draft script for "In a Mirror, Darkly", a note reads, "We’ll suggest the Defiant is a slightly newer vessel than Kirk’s ship; the exterior shows slightly more detail... intricate hull plating patterns can be visible in reflected light, etc."
The studio model of the Defiant in the original series was a reuse of the original Enterprise. The CGI model of the Defiant used in Star Trek: Enterprise was wholly built by Koji Kuramura. Nacelles, lighting and certain textures were "tweaked" by Rob Bonchune. The work was done at Eden FX, with reference help from Doug Drexler. 
According to Bonchune, the location of the aft torpedo launcher on the CGI model of the Defiant was "the little round port right between the impulses engines. We tried to make it logical with what existed so we didn't have to make a new hole on the ship. Everyone agreed, except that apparently if you frame by frame it, they actually come from the hangar bay phaser mounts. Someone in the chain ether decided against it or didn't know. Even one of the writers was surprised it hadn't been done as discussed." 
Star Trek: Enterprise teleplay writer Mike Sussman noted in his "In a Mirror, Darkly, Part II" audio commentary that the aft phasers and torpedoes that the Defiant possessed indicated a variation from its Constitution-class sister ship, the USS Enterprise, as that ship apparently lacks or at least does not make on-screen usage of those weapons. It should be noted, however, that in the original series episodes "Arena", "Friday's Child", and "The Doomsday Machine", verbal reference to the Enterprise's aft phasers can be heard in a stock voice loop. Additionally, reference to starboard banks is made in "Balance of Terror", as well as the port weapons mentioned in "Mirror, Mirror".
The Defiant's mission patch was an insignia similar to the pennant on the sides of TOS starships and seen as a set decoration on starbases of that era. A stylized version of this shape makes up the 2150s Earth Starfleet insignia. Three Defiant insignia badges; one command, one science and one engineering were sold in the 40 Years of Star Trek: The Collection auction for US$550 (US$660 with premium). 
During the events of the Glass Empires, the Defiant acted as the flagship for the Terran Empire. It would also serve as the prototype for many other Constitution-Class vessels, as well as newer, more advanced designs.
In the Star Trek: SCE novellas Interphase, Book One and Interphase, Book Two, the crew of the USS da Vinci rescue the damaged starship Defiant from interphase and the Tholians in the year 2376; the novellas were written before "In A Mirror, Darkly" was produced.
In the DC Comics Special #2 (published late 1994), the story "Raise the Defiant" tells of the USS Enterprise working to recover the Defiant from the Tholian rift during the 2280s to recover a classified phase-inverter capable of detecting cloaked vessels.
On the Star Trek DVD, the special features reveal that the USS Defiant of the alternate reality caused by Nero's arrival in the 23rd century, while maintaining the same registry, is a Template:ShipType starship.