The soldiers of the UNSC, otherwise known as the UNSC Defense Force, are the military body of Earth and her Colonies. Orders are given from the United Earth Government to the UNSC High Command (HIGHCOM), which is controlled by the UNSC Security Council. The UNSCDF is comprised of the Army, the Navy, the Marine Corps, and the Air Force. Later on, around 2553, the UNSCDF formed a fifth branch of the military known as Spartans, a military branch based specifically around the genetically altered super humans.
Of all of these Military branches, the Navy is now the most powerful, as the Navy contains the Office of Naval Intelligence (ONI), UNSC Naval Fleet Command, the UNSC Logistics Operations Command, and the UNSC Naval Special Warfare Command.
Within the Air Force are a number of major commands tasked with similar administrative and operational roles. Of these commands are the Air Combat Command and Air Mobility Command.
The UNSC Marines are a large force of well-trained soldiers’ well in-compliment to the Navy as marines are deployed on most Navy-run Warships. Of the Marines, the most popular are the Orbital Drop Shock Troopers, or the ODST.
The UNSC Army is the branch of the UNSCDF that is the primary response to land-based battles. The UNSC Army controls every land-based military operations as they typically serve as the garrison force of Colony Worlds. The UNSC Army works in conjunction with the UNSC Navy forces to move and fight across the galaxy.