UNSC Naval Intelligence Directorate for Special Intelligence

Section Three was an autonomous command of the UNSC Office of Naval Intelligence responsible for special operations and black projects.

It would earn infamy during the War for hosting special access programs such as SPARTAN-II and SPARTAN-III, and was primarily responsible for earning ONI its legendary mythology as well as cultivating the no mercy, no ethics myth that surrounded ONI. This was perpetuated by the nature of Section Three's operations and also its subdivisions, which included the Department of Biological Warfare and other morally dubious organizations.

By 2531, Section Three would be led by Vice Admiral Margaret O. Parangosky, and Rear Admiral Rich would serve as Section Three's special operations chief while Captain Gibson would be Section Three's black operations director. After the War's end in 2553, Parangosky was promoted to the Director of the Office of Naval Intelligence, and her protegé, Rich, would assume control over Section Three. By 2561, Gibson would be promoted to rank of Rear Admiral and would become the coveted Chief of Section Three.