The Second Battle of Deep Space 9 was the opening battle of the Dominion War. The battle began when Dominion forces attacked the station in an attempt to prevent Starfleet from mining the entrance to the Bajoran wormhole with self-replicating mines, which would prevent further Dominion forces from entering the Alpha Quadrant. Starfleet was ultimately successful in setting the minefield, though the station was lost to the Dominon. The station would be retaken by a combined Federation-Klingon offensive the next year.