In 2374, the Valiant, a Defiant-class Federation starship, was under the command of Captain Ramirez. The ship was on a training mission to circumnavigate the Federation with a crew of cadets from Starfleet Academy's elite Red Squad.
The crew was trapped in Dominion space when the war broke out, and all of the regular officers were killed. Before he died, Ramirez ordered 22-year-old cadet, Tim Watters, to assume command. For eight months, Watters attempted to complete the Valiant's mission and gather data on a new Dominion battleship.
When the Valiant saved Jake Sisko and Nog from a Jem'Hadar ship, Nog joined the crew as chief engineer. While undertaking an impossible mission to destroy the deadly Dominion battleship, the Valiant was destroyed. Only Jake, Nog and one other crew member survived.