The Vengeance-class destroyer was a class of guided missile destroyers that served in the UNSC Navy from 2544 onwards. The Vengeance-class was designed to replace or supplement several classes of destroyers already in UNSC service, most of which were both worn out from exhaustive service and outdated in design. The class incorporated many lessons hard learned by the UNSC during the Human-Covenant War, in which Covenant warships thoroughly outmatched Humanity's finest vessels at every encounter. Innovative design features included three full sized fusion reactors, extensive automation to reduce crew requirements, redesigned magnetic accelerator cannons and a significantly expanded armament. The Vengeance-class's design also incorporated some of the more cost-effective 'stealth' measures inc