From Halopedia, the Halo wiki
During the Battle of Draetheus V, the 3rd Platoon was deployed by the UNSC Eminent Domain onto Draetheus V's moon X50. It was the first to land on the moon, while the landing zone was less then a mile from Research Facility Alpha, during the landing they were scattered across the Glacial Perch mountain range. They were quickly surrounded by Covenant infantry and took heavy losses. Spartan Davis managed to rescue a few of the Helljumpers while clearing a landing zone for a second platoon.
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