4-01: The Way of the Warrior, Part I
When a Gowron-lead fleet of Klingon attack ships arrives at DS9, Sisko calls in a familiar Klingon expert for reinforcement.
4-03: The Visitor
When a freak accident traps Sisko in a time paradox, only re-appearing every few years, Jake spends the remainder of his life trying to save him.
4-13: Return To Grace
Kira assists Gul Dukat, now in command of a freighter, to stop a Klingon Bird-of-Prey that destroyed an outpost with a joint Bajoran and Cardassian delegation.