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Ship image.
Affiliation: Federation; Starfleet
Type: escort; destroyer
Service period: 2370-25th century
Length: 170.68 meters
Width: 134.11 meters
Height: 30.1 meters
Mass: 355,000 metric tons
Decks: 3; 5 deck areas
Crew: 40–47; 150 (evac; limit)
Maximum speed: warp 9.982 for 12 hours
Cruising speed: warp 6
Armaments: 4 pulse phaser cannons;
2 phaser arrays;
2 torpedo launchers
Defences: deflector shield; ablative armor
Auxiliary craft: 2 type 10 shuttlecraft;
4 shuttlepods

The Defiant-class was a type of Federation starship in use by Starfleet from the 24th century into the 25th century. Although officially designated as an escort, the Defiant ships were the first type of starship Starfleet ever created as a dedicated-purpose warship, and they are sometimes referred to as destroyers.

The USS Defiant was the first of what was to be a new Federation battle fleet. Starfleet abandoned the project when the Borg threat became less urgent; also, design flaws turned up, nearly destroying the Defiant during its initial shakedown cruise.

The Defiant prototype was pulled out of storage in 2371 when the Dominion threat emerged. After several upgrades by Deep Space 9 Operations Chief Miles O'Brien, the ship was deemed worthy of use and more ships of the class were constructed.


The Defiant was conceived as Starfleet's first warship in response to the many new threats faced by the Federation in the mid-24th century. The vessels were purposed as a compact design, packing a great deal of weaponry into a very small, maneuverable ship. As such, many of these vessels were fielded in battle during the Dominion War. The class has a compact warp core that produces enough energy to power a vessel four times larger than the class.


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 class was the first that Starfleet ever developed purely as a warship—but for years following the Borg's early incursions, the expected invasion never materialized—the prototype USS Defiant spent much of its time in space dock in the Utopia Planitia Fleet Yards. Rising hostilities with the Dominion spurred the Defiant into full service, assigned to Deep Space 9 in 2371 and fitted with a Romulan cloaking device to defend the station from Dominion attack and conduct undercover operations in the Gamma Quadrant.

Star Trek Roleplaying Game Player's Guide contradicts this by stating the the warship design was started in 2366, after the "initial contact" with the Borg.

By the time the situation escalated into full-scale war, several Defiant-class starships had been put into service and performed admirably. The original USS Defiant was destroyed by a Breen energy dampening weapon in 2375.

Following the Dominion War Starfleet developed a ship based on the lessons of the Defiant-class, the first and so far only vessel of this type, the USS Incursion is fitted with a holographic masking system and is operated by Starfleet Intelligence.


Defiant-class vessels crewed 50 officers and crew, with room for a maximum of 150 in evacuation situations. The Defiant vessels weighed 355,000 metric tons, measured 170.68 meters in length, 134.11 meters in width and 30.1 meters in height. The Defiant had a warp core power plant rated at over 1,500 cochrane units in output, feeding two warp nacelles. The warp drive was rated for a maximum output of warp factor 9.982 for 12 hours. The ships of the Defiant-class were also fitted with two impulse engine fusion reactor plants and thrust emitters.

The USS Defiant firing quantum torpedoes

The vessels have ablative armor to absorb enemy weapons fire and were fitted with four front-facing pulse phaser cannons, and conventional phaser arrays placed along the hull. Defiant ships also are equipped with two front-facing torpedo launchers and one aft launcher, capable of firing either photon torpedoes or quantum torpedoes. In an extreme situation the Defiant-class's nose section, which contained the vessel's stock of torpedoes, could be separated as a last resort to act as a large projectile.

The Defiant-class was one of the few classes of Starfleet starships capable of planetary landing and lift-off. The compact type-10 shuttlecraft was designed alongside the Defiant-class and two can be held in its shuttle bay. In the later 24th century, the Defiant-class was slated to continue production at the ASDB Integration Facility at Antares Fleet Yards shipyards, on Antares IV.

Like other Federation and starfleet ship designs, the Defiant-class was fitted with intercooler systems to cool the warp and impulse engines and the power transfer grid. The plasma intercooler was fitted with safeties which could be taken offline at the discretion of the ship's chief engineer. Both Miles O'Brien and Nog had performed this action, in order to coax better performance from the engines, aboard the USS Defiant and the USS Valiant, respectively.

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