Star Trek has had four starships named USS Defiant, especially the vessel in Star Trek: Deep Space Ninebut they don't share the same legacy. While the most famous Star Trek ship is the USS Enterprise, shows like Star Trek: Voyager and Star Trek: Discovery had their own eponymous starships which each boasts historic voyages. However, the starships named USS Defiant all had very eclectic histories that altered the fate of the Prime and Mirror Universes.

Star Trek: The Original Series was the first to introduce the USS Defiant, which was nearly identical to the Constitution-class Enterprise commanded by Captain James T. Kirk (William Shatner). The 23rd century Defiant is infamous for being lost in space, but it actually both time-traveled to the 22nd century and crossed over to the Mirror Universe. Meanwhile, most Trekkers are more familiar with the 24th century USS Defiant in Star Trek: Deep Space Nine, which was commanded by Captain Benjamin Sisko (Avery Brooks). There are actually three versions of DS9's Defiant, however, including a doppelganger built in the Mirror Universe to fight the Klingon/Cardassian Alliance.

Related: Star Trek: The Defiant's Original Name (& Why DS9 Changed It)

The DS9 season 6 episode "Valiant" also introduced the USS Valiant, an identical Defiant-class ship crewed by Starfleet's Red Squad cadets that was destroyed in a battle with the Dominion. Valiant was the original name intended for DS9's starship before it was changed to Defiant thanks to an edict by the studio, but this was a fortuitous switch. The name Defiant far better conveys the scrappy nature of Star Trek: Deep Space Nine, which was a black sheep Star Trek show in its time that has come to be regarded as an influential forebearer of Peak TV and is now seen as one of the best Star Trek series of all.

It took 3 seasons for the space station-set DS9 to get its own starship, but the Defiant has since become one of Star Trek's most famous and beloved ships, even though it, confusingly, has no shared history with the 23rd-century starship of the same name seen in TOS and in Star Trek: Enterprise.

USS Defiant - 23rd Century

USS Defiant NCC-1764

The Constitution-class USS Defiant (NCC-1764) made its first appearance in TOS season 3's "The Tholian Web" and it was trapped in a phenomenon called a spatial interphase. The insanity caused by the phenomenon caused the crew to kill each other and the Captain's neck was found broken when the crew of the Enterprise beamed aboard. The Defiant then vanished and it wasn't until Star Trek: Enterprise that the fate of the Defiant was revealed almost 40 years later.

As seen in Star Trek: Enterprise season 4's "In A Mirror Darkly" two-parter, the Defiant not only jumped into the Mirror Universe but it time-traveled to the 22nd century as well. The Tholians took possession of the Defiant but the 23rd-century starship was liberated by Commander Jonathan Archer (Scott Bakula), who planned to use its advanced technology to conquer the Terran Empire and declare himself Emperor. But Archer was betrayed by Hoshi Sato (Linda Park), who took command of the Defiant and declared herself Empress. It's not known what eventually happened to the Defiant, whether it was used as part of the Terran Starfleet or if it was stripped down for its parts and technology.

Related: Star Trek: Discovery Revealed The Mirror Universe's 32nd Century

Nevertheless, the presence of the Defiant changed the direction of the Mirror Universe as it gave the succeeding line of Terran Emperors, including Star Trek: Discovery's Philippa Georgiou (Michelle Yeoh) knowledge of the parallel reality, including the existence of the Federation, although this information was kept secret from most Terrans to keep them from being "contaminated" by the Federation's values. The Defiant's power and technology also gave the Terrans a leg up on the rest of the Alpha Quadrant and contributed to the Terrans' dominance until their empire eventually collapsed.

USS Defiant - 24th Century

Star Trek DS9 Defiant

In Star Trek: Deep Space Nine's 24th-century era, the name "Defiant" was resurrected for the Defiant-class starships, which was designed with the express purpose of defeating the Borg in battle. In fact, Benjamin Sisko, a survivor of Star Trek: The Next Generation's Battle of Wolf 359 against the Borg, was one of the designers of the Defiant, but the prototype warship was overpowered, over-gunned, and its design flaws threatened the ship to fly apart. In his third year of commanding DS9, Sisko requested the Defiant (NX-74205) be assigned to him to meet the threat of the Dominion. Captain Sisko commanded the Defiant until it was destroyed in the Dominion War's Battle of Chin'toka during DS9 season 7.

DS9's Defiant was a unique and beloved starship in Star Trek canon. The small and spartan vessel wasn't designed for families and it boasted features like pulsed phaser cannons, quantum torpedoes, ablative armor, and a Romulan cloaking device, making the Defiant a rare Starfleet ship authorized to use a practical invisibility screen. The "tough little ship" also appeared in the feature film Star Trek: First Contact, where it survived a battle with a Borg Cube and was left "adrift but salvageable". While Paramount and Star Trek producer Rick Berman initially resisted DS9 getting its own starship, the Defiant proved to be a necessary addition to the series that vastly opened up DS9's storytelling possibilities. It's now hard to imagine Star Trek: Deep Space Nine without the Defiant, which has taken its place among Star Trek's greatest starships.

ISS Defiant - Mirror Universe

Mirror Defiant DS9

The Mirror Universe's ISS Defiant (NX-74205) was built from the design specs of the Prime Universe's USS Defiant which were stolen from Deep Space Nine by "Smiley" O'Brien (Colm Meaney). In the DS9 season 4 episode "Shattered Mirror", the Terran Resistance built their Defiant to defend Terok Nor from the Klingon/Cardassian invasion fleet looking to retake the station. However, the Terrans ran into the same problems in regards to the Defiant's design flaws, the Prime Universe's Captain Sisko was tricked into traveling into the Mirror Universe to fix the starship before the Battle of Terok Nor.

Related: Star Trek: The Mirror Universe's History Explained

Captain Sisko had the ISS Defiant's inertial dampeners overhauled to enhance the ship's structural integrity and the repairs were completed in time for the battle. With Sisko in command, the Defiant managed to do enough damage to the Alliance's flagship that the Regent, Worf (Michael Dorn), was forced to retreat. The ISS Defiant later reappeared in DS9 season 7's "The Emperor's New Cloak", where it defeated Worf's ship again thanks to sabotage, and the Terrans were able to take the Regent prisoner.

USS Sao Paulo Renamed Defiant

USS Sao Paulo Bridge Sisko

In the final episodes of Star Trek: Deep Space Nine, Captain Sisko received a brand new Defiant-class starship, the USS Sao Paulo (NCC-75633). However, Admiral Ross (Barry Jenner) had a surprise for Sisko: special dispensation to rename the Sao Paulo the USS Defiant. The new Defiant boasted upgrades like redesigned shield generators, a more powerful warp drive, and a slightly different bridge interior. Captain Sisko commanded the second Defiant into the Federation's victory in the Dominion War.

In the documentary What We Left Behind, the apocryphal first episode of Star Trek: Deep Space Nine season 8 revealed that the Defiant was under the command of Captain Nog (Aron Eisenberg) 20 years later, before it was destroyed in what would ignite a new, season-long mystery.

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