In the Star Trek: Deep Space Nine episode "Call to Arms," one of the largest battles at DS9 is fought. Starfleet Command had ordered Captain Benjamin Sisko to mine the entrance to the wormhole with self-replicating mines. Seeking a diplomatic solution, the Dominion sent its negotiator, Weyoun, to the station. He asked that the minefield be deactivated, but Captain Sisko refused. The Dominion abandoned its diplomatic approach; they sent an army from Cardassia, led by Gul Dukat and Weyoun, to attack Deep Space Nine.
In the ensuing battle, the Federation was forced to evacuate Deep Space Nine, but not before destroying or taking much of the valuable technology. The Dominion established a presence on newly renamed Terok Nor, and would remain there for several months.
Gul Dukat picks up a message from Sisko: his baseball. It was Sisko's way of saying that he'd be back.