From Halopedia, the Halo wiki
Glacial Perch, also referred to as the Perch, was a mountain range on X50, the moon of Draetheus V. The mountain range had a sharp rock face and was west of Research Facility Alpha at Mirror Flats.
During the Battle of Draetheus V, Merg Vol's Covenant took control of Glacial Perch, believing it held strategic importance. Meanwhile, Covenant forces were relying on Type-25 Spirit dropships to attack the nearby Research Facility Alpha. To counter the attacks, Spartan Edward Davis and several UNSC Marines defeated the Covenant forces at Glacial Perch. Davis established several air defenses on the Perch, including two M9 Wolverines.
Later in the battle, Orbital Drop Shock Troopers from the 3rd Helljumper Platoon were deployed by the ship UNSC Eminent Domain onto X50. While the landing zone was less then a mile from Research Facility Alpha, during the landing the ODSTs were scattered across the mountain range. The ODSTs were quickly surrounded by Covenant forces and took heavy losses. Spartan Davis later set out to clear a landing zone for the second wave of ODSTs. After he wiped out the Covenant forces at the landing zone at the Perch, Davis regrouped with the ODSTs and wiped out the rest of the Covenant forces at the mountain range.
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