The destruction in 2374 of the USS Valiant, a Defiant-class ship run by Red Squad cadets behind enemy lines, during an ill-judged attack on a Dominion battleship.
The loss of the USS Valiant is the subject of the Deep Space Nine episode Valiant. Jake Sisko and Nog are rescued from a Jem'Hadar attack by the Valiant, which left on a training cruise before the war with a crew of elite cadets from Red Squad. The officers were killed when fighting began, and the dying captain gave command to Cadet Tim Watters.
Watters has kept the ship in enemy space for eight months to finish its mission, and he stays awake with stimulants. He makes Nog chief engineer. After locating a huge new Dominion battleship, he decides to destroy it instead of reporting it, and only Jake argues against him.
The plan to attack a weak point in the battleship's structure fails, and the Valiant is torn apart. Jake, Nog and Cadet Dorian Collins are the only ones to reach an escape pod, and the Defiant picks them up.