Deep Space Nine is a space station located near a stable wormhole between the Alpha and Gamma quadrants of the Milky Way Galaxy. The final episode of the series with the same name, “What You Leave Behind” sees the end of the Dominion War as the alliance of Starfleet, the Klingons, Romulans, and rebel Cardassians launch a final attack against the Dominion on Cardassia Prime.

Deep Space Nine began while The Next Generation (1987) was still on the air. It distinguished itself from both of its predecessors by localizing its stories to the happenings of a remote space station as opposed to onboard an exploratory vessel. It also boasted markedly different storytelling styles, with tonally darker content and a more prominent focus on serialization than those before it. Paramount Domestic Television | CBS

The Battle of Cardassia was the final battle of the Dominion War, fought in late 2375. The Federation Alliance, the forces of the United Federation of Planets, the Klingon Empire, and the Romulan Star Empire, launched an invasion of the Dominion-held Cardassian Union, with the goal of capturing the Dominion’s capital on Cardassia Prime.

“This war, captain. It has to end.”
“And it will. Soon. One way or the other.”

– Odo and Benjamin Sisko, 2375 (“What You Leave Behind”)

The battle would ultimately lead to the Dominion’s unconditional surrender of all forces in the Alpha Quadrant.