Valiant

Jake and Nog are rescued from a Dominion attack by the USS Valiant, crewed entirely by Red Squad cadets after a Dominion ambush killed its officers. Acting captain Tim Watters has kept the ship going on its original mission of gathering intelligence on a new Dominion battleship. Nog repairs the engines and becomes chief engineer, while Jake remains an outsider.
Once the scan is complete, Watters decides to attack the battleship, believing it has a weak point. Jake argues that his father would never risk such an attack and is thrown in the brig, but the cadets follow Watters eagerly. The strike fails, the battleship returns fire, and Watters and most of the crew are killed. Nog and the cadet Collins free Jake and escape in a pod before the Valiant explodes, and the Defiant picks them up. The sixth-season episode warns against hero worship and blind obedience in wartime.