From Halopedia, the Halo wiki
UNSC Navy, UNSC Marine Corps
Helps the player learn the basic controls of Halo 3.
This unidentified Corpsman is a member of the UNSC Navy's Hospital Corps. His squad found Spartan John-117 when the latter landed in a jungle near Mount Kilimanjaro in Tanzania during the Battle of Earth. The Corpsman helped the Spartan regain some of his movement before moving toward Crow's Nest.