The battle at the end of 2373 in which Dominion and Cardassian forces under Gul Dukat took Deep Space 9 from Starfleet, the opening engagement of the Dominion War.
The Second Battle of Deep Space 9 is shown in Call to Arms, the last episode of the fifth season of Deep Space Nine. With Dominion convoys reaching Cardassia every week, Benjamin Sisko has the Defiant lay a field of cloaked, self-replicating mines across the mouth of the wormhole. Weyoun demands that they be removed and Sisko refuses.
So that Bajor will be spared, Sisko urges its government to sign a non-aggression pact with the Dominion. The enemy fleet arrives before the minefield is switched on, and the station's shields and weapons hold long enough for the work to be finished. Starfleet then abandons the station, leaving its computers wrecked.
Kira Nerys, Odo and Quark stay behind as Dukat and Weyoun take possession, and Jake Sisko remains as a reporter. A Federation and Klingon force uses the diversion to destroy the Dominion shipyards at Torros III.