Dominion War

The Dominion War is an extended plot concept developed in several story arcs of Star Trek: Deep Space Nine, an American science-fiction television series produced by Paramount Pictures. In the fictional Star Trek universe, the Dominion War is a conflict between the forces of the Dominion, the Cardassian Union, and, eventually, the Breen Confederacy against the Alpha Quadrant alliance of the United Federation of Planets, the Klingon Empire and, later, the Romulan Star Empire. The war takes place in the final two seasons of the series, but has been gradually built up to over the course of the five preceding seasons.

The principal setting of the series is the Starfleet-controlled space station Deep Space Nine, located adjacent to the mouth of a stable wormhole near the planet Bajor. The Bajoran wormhole provides instantaneous travel to the Gamma Quadrant, a region on the other side of the galaxy. During the second season of Deep Space Nine, the Dominion, a powerful empire in the Gamma Quadrant, is introduced; and over the course of the second and third seasons, more information about the Dominion is revealed. Conflict escalates through the fourth and fifth seasons, as the Dominion infiltrates Alpha Quadrant powers and eventually forms an alliance with Cardassia; open warfare begins at the end of the fifth season, when the Dominion briefly occupies Deep Space Nine, and continues until the Dominion is finally defeated in the series finale.

The Dominion War arcs present themes that challenge the values of the characters in a manner not attempted in earlier series of Star Trek. Developing the plot of the Dominion War also altered how the series was scripted, shifting the emphasis from an episodic to a serialized narrative format.