Date: 2373–2375

The Federation’s discovery of the Bajoran Wormhole, which allowed regular travel to the Gamma Quadrant. Contact with the Dominion soon followed, and the situation escalated as Changelings began infiltrating the Alpha Quadrant, impersonating key political and military figures. These covert actions destabilized interstellar relations and laid the groundwork for open conflict. During this period, the Cardassian Union formally aligned itself with the Dominion, while the Dominion secured nonaggression pacts with Bajor and the Romulan Star Empire. As tensions escalated into war, the Federation mined the Alpha Quadrant entrance to the Bajoran Wormhole to block Dominion reinforcements. In response, Dominion and Cardassian forces attacked and captured Station Deep Space Nine. Starfleet later destroyed Dominion shipyards at Torros III, and Captain Benjamin Sisko led a joint Federation–Klingon fleet to retake Deep Space Nine. Despite these successes, the Dominion gained ground, occupying worlds such as Betazed and Benzar and inflicting heavy losses across the Alpha Quadrant. The war expanded further when the Romulan Star Empire joined the Federation Alliance following the assassination of Senator Vreenak, solidifying a major turning point in the conflict. The Federation Alliance captured the strategically vital Chin’toka system in Cardassian space and seized a Dominion subspace communications array on AR-558. However, the balance shifted again when the Breen Confederacy entered the war on the Dominion’s side and launched a devastating surprise attack on Earth. Using Breen energy-damping weapons, Dominion–Breen forces recaptured the Chin’toka system. Internal resistance within the Dominion alliance began to fracture its control when Damar organized a Cardassian resistance movement. This resistance sabotaged Dominion operations, including the destruction of a cloning facility on Rondac III. In the final phase of the war, the Federation Alliance launched a full-scale assault on Cardassia Prime, with Cardassian forces turning against the Dominion. Amid catastrophic civilian losses, Odo cured the Female Changeling of the morphogenic virus and persuaded her to order a ceasefire, bringing the war to an end. The war formally concluded with the signing of the Treaty of Bajor aboard DS9. The Female Changeling voluntarily surrendered to face trial for war crimes, the Cardassian Union collapsed in the aftermath of the fighting, and Dominion forces withdrew permanently to the Gamma Quadrant. Borders and territorial control largely returned to their pre-war status, while Odo returned to the Great Link to heal his people, leaving lasting political and moral scars across the Alpha Quadrant.