U.S.S. Defiant NX-74205

Defiant class (DS9 537)

The lead vessel of the Defiant class, the Federation Starship Defiant was officially classified as an escort, but began development in 2366 as a small, highly-powered, heavily-armed starship intended to defend the Federation against the Borg. The 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 and after design flaws turned up during the Defiant's shakedown cruise.

After its construction, the Defiant went on a trial run to the Romulan Neutral Zone, where it was tested under the command of Commander Benjamin Sisko. During this test run, the Defiant discovered a derelict D'Deridex class warbird in Federation space. Upon further investigation, the Defiant encountered a group of warbirds under the command of Valerius of the Tal Shiar, who had laid a trap for a rogue Vulcan criminal named T'Uerell. When Commander Sisko challenged the Romulan officer, Valerius's attack forced the Defiant to flee into a nebula, where it left an emergency distress beacon. When the U.S.S. Enterprise NCC-1701-D came to assist the Defiant, they discovered that the smaller vessel had fallen into Romulan hands, and the Romulans were beginning to study it at a secret base. A Starfleet task force managed to destroy the base and allow the Defiant to escape.

On Stardate 48213.1, the Defiant was assigned to Deep Space 9—again under the command of Commander Sisko, who also commanded the station—to help counter the threat posed by the Dominion; the ship was equipped with a cloaking device on loan from the Romulan Star Empire. The ship had minimal crew accommodations, a small sickbay, and no provisions for families.

Following the Defiant's return to the Alpha Quadrant, Chief Miles O'Brien and Commander Sisko worked on the design flaws in the ship's systems, which led to the ship being sent to the Utopia Planitia Fleet Yards on Mars where the repairs were carried out over several weeks.

Soon thereafter, the Defiant was away from Deep Space 9 during the Cardassian incursions into Bajoran space during a crisis on Cardassia Prime when Goran Tokar was to announce his heir.

On Stardate 48467.3, Maquis member Thomas Riker hijacked the Defiant from Deep Space 9 to investigate a suspected Cardassian military buildup in the Orias system.

On Stardate 48481.2, the Defiant was caught in a temporal eddy and spared from catastrophic changes to the timeline during an accidental transport of several personnel to early 21st-century Earth, and the Defiant was able to make use of the temporal instability to rescue the missing crewmembers after they had repaired the damage to the timeline.

In 2371, in order to find Calculanthra, an Orion who had sold defective replicators that had made their way to Bajor, Sisko took the Defiant to Mephil Trantos. After Quark beat Calculanthra in a game of dabo, the Orion pursued the Defiant in the raider Laslapadil. The Defiant destroyed two of the raiders and disabled two more.

The Defiant was then assigned to investigate the threat of the Magellanic Hive after it destroyed and absorbed the Bajoran colony on Darane IV as part of a Grand Design, which involved dividing the hive into two units: one bound for Bajor, the other for Cardassia Prime. Although the Cardassian Third Fleet was able to destroy the hive headed to Cardassia at the cost of their own lives, Bajor was defended by the Defiant and several small fighters. Realizing they had no chance of defeating the hive, Commander Sisko attempted to negotiate with the leaders of the hive. Fortunately for the Bajorans, a civil war broke out aboard the hive regarding the original interpretation of their Grand Design, and the hive instead made Darane III their new home. Soon thereafter, the Defiant engaged and attacked the Rugg'l when the Cardassian ship attacked Deep Space 9.

About a month later, the Defiant traveled to the Gamma Quadrant to observe a subspace inversion of the Bajoran wormhole. During the mission, an accident in the engine room pulled Commander Sisko into subspace, spawning the D476 Timeline, but several decades later, an elderly Jake Sisko managed to prevent the accident. In the new timeline, the accident was averted, leaving Sisko, who still remembered the original timeline, disoriented but unharmed.

The Defiant battled the U.S.S. Lakota NCC-42768 when transporting Lieutenant Arriaga, a key witness in the case against Admiral Leyton's attempted coup, to Earth. While returning to Deep Space 9 several days later, Sisko diverted the Defiant to Trill after the Trill Symbiosis Commission urgently requested to meet with Jadzia Dax. About a month later, Sisko, Worf and Dax took the Defiant to Starbase 201 for a briefing on a mission to the Gamma Quadrant that Worf, Odo and Kira would be undertaking.

About a week prior to Stardate 50308.7, the Defiant was inadvertently transported back in time to Stardate 4523.3. Thanks to its cloaking device, it remained undetected by the U.S.S. Enterprise NCC-1701, which was at Deep Space K-7. The Defiant prevented a Klingon agent from the 24th century from assassinating Captain James T. Kirk of the Enterprise, and the ship returned to its own time.

Two months later, the Defiant was on a routine mission to test a new navigation grid when it received a distress call from the U.S.S. Amhurst. The Amhurst exploded and the Defiant pursued a Gorn ship believed to have been responsible into Restricted Sector One-Four-Bravo: Metron space. Sisko and Bashir were taken from the bridge of the Defiant to meet with a Gorn named S'Slee and the Metrons on the same planet James T. Kirk had been brought to more than a century before. Agreeing to preserve the Metrons' knowledge before they died out, Sisko took the Defiant to Venexar, where the ship launched an information pod that carried this knowledge to the planet's surface.

On Stardate 50976.2, the Defiant was aided by both Klingon and Romulan forces in fending off a Dominion force sent as part of a plot to kill off all the telepathic species in the Alpha Quadrant. About a week later, the Defiant encountered a settlement on the planet Gaia IV. While attempting to leave the planet, a future version of the ship was sent two centuries into the past, and the stranded crew was forced to live out their lives on the planet. The Defiant's crew elected to recreate the accident that led to their future counterparts being stranded on the planet rather than allow their eight thousand descendants be erased from history, but the alternate Odo reprogrammed the Defiant's computers to avoid the accident so that Kira would not die as she had in the original timeline.

When the Borg launched an invasion of the Federation on Stardate 50893.5, Admiral Jeremiah Hayes ordered the Defiant to join the fleet and specifically ordered Captain Sisko to remain on Deep Space 9, passing command to Worf. Starfleet Command feared that Sisko's previous experience with the Borg could have compromised the captain's ability to effectively command in combat against the Borg. The Defiant was one of the first ships to arrive in the Typhon Sector to combat the Borg cube, which was on course for Earth. Under Worf's command, the Defiant fought a running battle with the Borg, scoring a number of impressive hits on the cube's surface. Captain Morgan Korsmo saw the damage the cube was inflicting on the Defiant from the bridge of the U.S.S. Excalibur NCC-26517. Korsmo wanted to help the Defiant, but saw that it was holding its own. The Defiant, which had continued fighting all the way to Earth, was seriously damaged by the Borg. Its shields had failed by this time and its weapons had been depleted. Worf was in the process of ordering the Defiant to ram the cube when the U.S.S. Enterprise NCC-1701-E arrived, which blocked an energy beam fired at the Defiant by the cube. The Defiant's life support system began to fail, and its crew was beamed aboard the Enterprise. The Defiant survived the destruction of the cube and Captain Jean-Luc Picard took great pleasure in telling Worf the Defiant was "adrift, but salvageable." The Enterprise followed a Borg sphere through a temporal rift, preventing the Borg from altering history. Upon their return, the Defiant was taken to Earth Station McKinley, where several small repair operations were begun. Later, Worf resumed command of the Defiant and returned to Deep Space 9, where Chief O'Brien completed the repairs.

Three months later, Dax commanded the Defiant on several missions, including an attack on a sensor array in the Argolis Cluster on Stardate 51145.3 and "playing possum" to attract Dominion ships and catch them unaware.

About a year later, shortly after completing a mission to Bolarus IX, Admiral Ross ordered the Defiant to Starbase 133 in preparation of the liberation of Betazed. During the battle, the Defiant and the Enterprise destroyed several Dominion ships. The Defiant later transported Deanna Troi, Elias Vaughn, Beverly Crusher, Data and Hent Tevren aboard from the Jarkana Mountains on Darona.

The Defiant was destroyed by Breen forces during the Battle of Chin'toka in 2375, just weeks before the end of the Dominion War.