The Federation Alliance, also known simply as The Alliance, was the accord between the United Federation of Planets, the Klingon Empire, and the Romulan Star Empire formed during the Dominion War. It was one of two belligerents in the war, the other being the Dominion-Breen Alliance.
The first offensive undertaken by all the members of the Alliance was the First Battle of Chin'toka. The Cardassian Liberation Front bolstered the Alliance to win the Battle of Cardassia and, ultimately, the war. The Federation Alliance gained a decisive victory at the end of the war and forced the Dominion to sign a treaty vowing never to enter the Alpha Quadrant with intents for conflict or subterfuge again.