UNSC Euphrates
From Halopedia, the Halo wiki
Summary
The UNSC frigate Euphrates was preparing to launch a reconnisance mission in 2552 when the Covenant attacked the planet Reach. The vessel was ordered to drop its mission and return to defend the planet, where it was probably destroyed.
The Euphrates was carrying an ONI prowler on board for its mission. Lieutenant Haverson suggested that the Ascendant Justice, under control of UNSC personnel, return to Reach and pick up that prowler and use it to repair the Ascendant Justice's damaged reactor, just before the "First Strike" mission.
