Benjamin Sisko served in and survived the Battle of Wolf 359 before being assigned command of the former Cardassian mining platform. Before he was assigned to command the station Deep Space Nine, he was responsible for designing the Defiant-class starships.
Sisko's leadership was instrumental in keeping the Bajorans friendly to the Federation. He lead DS9 through several key combat engagements against the Klingons, Cardassians, and Dominion forces. His deployment of cloaked self-replicating mines prevented Dominion forces from receiving reinforcements through the Bajoran Wormhole. Retaking DS9, he led the Federation to victory over Cardassia and The Dominion.
As part of his taking command of Deep Space Nine, he and Jadzia Dax discovered the Bajoran Wormhole. They entered the wormhole and confirmed it's opening in the Gamma Quadrant before attempting to return back to DS9. On the way back, the runabout was stopped inside the wormhole by the aliens that lived within, known to the Bajorans as The Prophets. After returning Jadzia Dax to the station, they spent an extended period talking with him, calling him nothing more then "the Sisko". After this period, he left the wormhole towing a Cardassian warship commanded by Gul Dukat, which had entered the wormhole while Sisko was talking with the Prophets. Sisko had faced his own thoughts and fears from his wife's death at Wolf 359 during this time, earning the Prophets' respect. During his discussions with them, they allowed use of the wormhole, even though it hurt them when ships passed through it. Because he had talked with the Prophets, the Bajorans began referring to Commander Sisko as "the Emissary" from that point onward.
As part of this connection with the Prophets, Sisko has contact with them on multiple occasions. One notable instance led to the destruction of a Dominion fleet on it's way to reinforcing their forces in the Alpha Quadrant.