I don't have the time for this, so I just got this from the halo wiki: The SPARTAN-III program was both the successor and supplement to the SPARTAN-II program. Created and engineered by Colonel James Ackerson of the Office of Naval Intelligence, the SPARTAN-III soldiers were to be the next generation of supersoldiers. Composed primarily of vengeful orphans from fallen colonies, they would be cheaper to arm, train, and produce; being chosen from a wider pool of candidates, they would also be more numerous than their SPARTAN-II predecessors. They would rely on superior battle tactics, and teamwork rather than advanced technology and equipment to achieve their combat effectiveness. Now for Noble 6: SPARTAN-B312 was taken out of Beta Company immediately after training, according to a communiqué from Kurt Ambrose to Franklin Mendez that was sent in May 2545, two months before Operation: TORPEDO. Later career “Six has made entire militia groups disappear.” — Dr. Catherine Halsey Over the course of B312's career, the SPARTAN gained a high reputation as an efficient lone-wolf assassin, having single-handedly broken organizations and made entire militia groups disappear. B312 was also a test pilot in a top-secret UNSC project, the Sabre Program, which resulted in the development of the YSS-1000 "Sabre"-class starfighter. B312 used these skills to great effect in a counter-insurgency operation on Mamore on May 10, 2552. At one point, B312's superior allegedly used the SPARTAN as "his own private grim reaper", and because of this, he was reluctant to have the Spartan assigned to Noble Team. On July 24, 2552, SPARTAN-B312 was assigned to Noble Team as a replacement for its previous sixth member, Thom-293. Six, having recently arrived on Reach, joined the team just in time to participate in an operation to investigate a communications blackout at the Visegrád Relay, a mission which led to the first confrontation with Covenant forces on Reach.