The Starfleet 2nd Fleet was a military unit, a fleet group of the Federation Starfleet during the Dominion War. In 2374's Operation Return, the 2nd Fleet was teamed with the 5th Fleet in a victorious effort to retake Deep Space 9. As he assembled his fleets in preparation, Sisko caught the notice of Dominion strategists when he withdrew the 2nd Fleet back through the Kotanka system. The 2nd Fleet later made three separate failed attempts to liberate Betazed. (DS9 episodes: "Call to Arms", "A Time to Stand", "Favor the Bold", "Sacrifice of Angels", "The Sound of Her Voice"; novelizations: "Call to Arms..." and "...Sacrifice of Angels"; RPG reference book: The Dominion War Sourcebook: The Fires of Armageddon)