The UNSC Everest was the flagship of both UNSC Battle Group X-Ray, and later of Battle Group India. It was commanded by Vice Admiral Preston Cole from 2525 until its apparent destruction in 2543. During that time, the Everest saw significant combat, being the lead warship during the Second Battle of Harvest, the Battle of the Great Bear, and largest and its final and largest battle, the Battle of Psi Serpentis. The Everest was lost, along with Preston Cole and its entire crew, when the gas giant Viperidae was briefly ignited during the Battle of Psi Serpentis, engulfing both the Everest and an entire Covenant fleet of over three-hundred Covenant ships. It is suspected that the Everest actually made a last-second slipspace jump and survived the battle, though it has never been found.