Mission 3: Reinforcement of the Perch

"The UNSC's Research Facility Alpha was constructed at the base of an ancient Forerunner structure recently discovered by the UNSC. When it became clear the Covenant were heading for the Forerunner structure, UNSC Command feared Alpha facility would be crushed. The Covenant were relying heavily on drop ship insertion and Spartan Davis realized they would be vulnerable to focused anti-aircraft fire, so he began establishing air defenses west of Alpha facility at a location designated Glacial Perch. Unfortunately, the Covenant had identified the need to secure this area, and when Davis arrived, Glacial Perch was swarming with Grunts and Elites."

- Mission summary