The Pioneer-class destroyer was a class of guided missile destroyers that served in the UNSC Navy between 2525 and 2565. The class was introduced just months before the start of the Human-Covenant War, with only a handful of vessels in service, meaning that early lessons learnt in combat with the Covenant were quickly implemented in subsequent ships. The class gradually replaced several legacy destroyer classes in UNSC service, and by 2550 was the second most numerous UNSC warship behind the Remembrance-class frigate . Over 1800 examples of the class were constructed before the Battle of Earth in October- November 2552, of which just over 400 remained in service. The class went on to serve throughout the Remnant War, although from 2553 construction instead shifted to the Vengeance-class de