The Defiant-class was one of many new Starfleet classes developed in response to the Borg threat following Starfleet's tragic losses in the Battle of Wolf 359. The starship was developed at the Antares Fleet Yards and was the first vessel Starfleet ever developed purely as a warship. However, the expected Borg invasion never materialised and the prototype USS Defiant spent much of its time in space dock due to design flaws. Rising hostilities with the Dominion threw the USS Defiant into active service and it was assigned to Deep Space 9 in 2371. Numerous adjustments and upgrades were made to the starship, including being fitted with a Romulan Cloaking device, to defend the station from Dominion attack and conduct undercover operations in the Gamma Quadrant.
The success of the USS Defiant gave new life to the class. Additional vessels were ordered, implementing the changes made to the class's namesake. As other Defiant-class starships left the shipyards they were placed in service defending Federation space and in combat in the Dominion War.
In the Cryptic universe, four variants of the Defiant-class were developed: the Gallant, Vigilant, São Paolo, and Valiant.
Launched in response to the fallout from the Khitomer Accords in 2399, the Gallant variant was a unique take on the standard Defiant. The unique nose of the Defiant-class was removed and weapon pods were placed on struts protruding from underneath the starship.
Just as powerful and nimble as the standard Defiant-class, the Vigilant subclass was larger and featured an updated nacelle design. The starship was also equipped with an adaptable, multipurpose space to counterbalance the straight warship design of the Defiant.
The 'São Paolo' variant was a 25th century take on the famed Defiant-class. It had exposed, forward-swept warp nacelles and a more faceted main deflector. It was also constructed using the white hull coloring favored by Starfleet engineers for refit vessels in the early 25th century.
The vessel was also developed with Quad Phaser Cannons. This fearsome energy weapon was a specialized cannon that drew power from the ship's engines to deal massive damage to an enemy.
Carrying more armor and a larger torpedo payload, the Valiant-class we designed to combat the threats encountered by Starfleet in the 25th century. The vessel had a stubbier nose and longer engine struts than the Defiant-class.
- USS Belfast (NCC-75633-C)
- USS Bogota
- USS Defiant (prototype, NX-74205)
- USS Galaga (NCC-25681)
- USS Gallant (Gallant-class prototype, NX-93881)
- USS Indefatigable (NCC-81522)
- USS Indefatigable (São Paolo-class, NCC-92035)
- USS Mongoose (NCC-92945)
- USS Nike (São Paolo-class, NCC-93888)
- USS São Paulo (NCC-75633, renamed Defiant)
- USS São Paolo (São Paolo-class prototype, NCC-75633-A)
- USS Valiant (NCC-74210)
- USS Vigilant (Vigilant-class prototype, NCC-94794)
- Defiant class article at Memory Alpha, the canon Star Trek wiki.
- Defiant class article at Memory Beta, the non-canon Star Trek wiki.
- Defiant class article at Star Trek Expanded Universe.
- Tactical Escort article at The Star Trek Online Wiki.