The First Battle of Deep Space 9 opened the Federation-Klingon War of 2372-2373. In early 2372, shortly after an overwhelming invasion of the Cardassian Union by the Klingon Defense Force, a task force led by Chancellor Gowron and General Martok launched an attack on the Federation space station of Deep Space 9, in an attempt to force Captain Benjamin Sisko to relinquish the members of the Cardassian government under his protection.
The Klingon fleet consisted of over 50 warships including at least 34 Birds-of-Prey, 6 Vor'cha-class attack cruisers, and 11 K't'inga-class battle cruisers. The IKS Negh'Var served as the flagship. Starfleet had used the year leading up to the battle to prepare the station for a massive attack by the Dominion, and these preparations included the installation of new torpedo launchers and phaser emitters, as well as a stockpile of five thousand photon torpedoes.
The Klingons under-estimated the station's defenses, and were unable to take the station before the arrival of Starfleet reinforcements. Faced with the prospect of massive losses and an escalating war on two fronts, Gowron ordered his forces to withdraw.