From Halopedia, the Halo wiki
UNSC Marine Corps
Papadakis is a private in the UNSC Marine Corps. He fought in the Battle of the Etran Harborage as part of the Marine contingent aboard the UNSC Spirit of Fire during the Human-Covenant War in 2531. After using the vessel's Slipspace drive as an improvised bomb to destroy the Shield World, most of the Spirit of Fire's crew, including Papadakis, entered cryostasis.