DS9 Season 4 Episode 14 Return to Grace

Plot

Major Kira is shocked to find out that Dukat will be captaining the freighter transporting her to a conference regarding the Klingon threat. Dukat was recently demoted when it became publicly known that he has a half-Bajoran daughter, and he now works in a dreary job flying an unremarkable trading ship.
When they arrive they find the conference site obliterated, and a Klingon Bird of Prey warship leaving the area, not even bothering to attack what it considers a lowly freighter. Kira suggests that they adapt the planet's weapons for use by the freighter, effectively turning it into a Q-ship, and then they head after the Bird of Prey. They soon find it, and after tricking the Bird of Prey into thinking they are carrying valuable cargo, use their new weaponry to cripple the Klingon vessel. After commandeering the Bird of Prey and transporting the Klingons to the freighter, Dukat mercilessly destroys the freighter. Dukat notifies his superiors of his capture of the Klingon ship, hoping to regain some respect and spur the Cardassians into fighting the Klingons; they offer him his old job back, but order him to take no further offensive actions against the Klingons.
Disgusted, Dukat vows to fight the whole Klingon Empire himself if he has to. He offers Kira a place on his crew, saying her experience as a resistance fighter would be valuable. She declines, taking Ziyal back to Deep Space Nine with her until Dukat's personal war is over.