The Defiance was an MC40a light cruiser used by the Alliance Fleet from the early days of the Rebellion in 3 BBY through the signing of the Galactic Concordance in 5 ABY, before being decommissioned following the formation of the New Republic. The Defiance was particularly notable for being the headquarters of the relatively famous Sapphire Squadron, and like the squadron it housed, the ship participated in some of the most significant battles of the Galactic Civil War. The vessel was captained by Commander Roy Vaykin throughout its service life.