Fireteam Aegis (sometimes stylized as AEGIS Team) was a fireteam-sized unit of Spartan commandoes which served as part of the SPARTAN-IV Program, under the direction of the Office of Naval Intelligence. Composed of one SPARTAN-IV, four SPARTAN-IIIs, and one SPARTAN-II, Aegis was formed in order to combine the experience and skill sets of different Spartan generations into a single unit superior to other S-IV units; while most other Spartan units answered only to the leadership of the Spartan branch and lacked formal ranks, Aegis was one of the few to remain attached to the ONI and its members retained Naval ranks as a result. Because of these differences, Aegis was classified as a top-tier asset and assigned to operations deemed too difficult or sensitive for less-qualified personnel. Its