Federation starship, Starfleet registry number NX-74205. Prototype for the proposed Defiant class, the second starship the bear the name. The Defiant was officially classified as an escort, but began development in 2366 as a small, highly-powerd, 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 desing flaws turned up during Defiant's shakedown cruise. In 2371, the Defiant was assigned to Deep Space 9 to help counter the threat posed by the Jem'Hadar, and was equipped with a clocking device on loan form the Romulans. Later that year, Maquis member Thomas Riker hijacked the Starship Defiant from Deep Space 9 to investegate a suspected Cardassian military buildup in the Orias system.
The ship had minimal crew accomodations, a small sickbay, and no provisions for families. The Defiant carried at least two shuttlecraft. In 2372, the Starship Defiant was flown to the Gamma Quadrant to observe a subspace inversion of the Bajoran wormhole. During the mission, an engine-room accident almost pulled Benjamin Sikso into subspace. Shortly afterward, the Defiant battled the Federation starship Lakota when the Defiant transported Lieutenant Arriga, a key withness in the case against Admiral Leyton in Leyton's attempted coup, to Earth.
In 2373, the Defiant, under the command of Lieutenant Commander Worf, was part of the Starfleet armada that intercepted a Borg cube at Earth on stardate 50893. The Defiant was seriously damaged and the surviving crew memebers were beamed aboard the U.S.S. Enterprise-E.