A Defiant-class warship crewed by Red Squad cadets that was trapped behind Dominion lines and destroyed in 2374.
The USS Valiant was a Defiant-class warship assigned to a training cruise for Red Squad, an elite group of Starfleet Academy cadets, during the Dominion War. When the ship's commissioned officers were killed in a Dominion attack, the cadets were left to run the ship themselves.
Cut off behind enemy lines for months, the cadets kept fighting under their acting captain, Tim Watters, who held them to a rigid sense of duty. In Valiant they rescued Jake Sisko and Nog, himself a former Red Squad member, from a Dominion ship and then decided to destroy a powerful new Dominion battleship.
The attack failed, and the Valiant was destroyed with nearly all hands. Jake, Nog and cadet Karen Farris escaped in an escape pod and were rescued, carrying word of the ship's fate back to Starfleet.