The Spartans are a UNSC affiliated group of supersoldiers, created by the Office of Naval Intelligence's Section Three. Which specializes in wetwork, covert, and black ops. Spartans are devised into three groups; Spartan-I's, also known as Project: Orion were the UNSC's first foray into funding supersoldiers. Although deemed a success, the project was too costly and was shut down. Spartan-II's were obviously Section Three's truly successful endeavor into supersoldiers, and the Spartan-II's are the stuff of legend. The Master Chief is a Spartan-II.
Finally we come to the Spartan-III's, these Spartans were separate from Dr. Halsey's work in that they were created by Colonel James Ackerson. Although Ackerson detested Halsey's Spartans as they succeeded everywhere he failed, he came up with the Spartan-III program as a cheaper and more survivable program as the Spartan-II's augmentation process was extremely deadly to the unfortunate candidates.
Ackerson's plan, however, stated that the Spartan-III's existed only as expendable assets. They were to engage the Covenant in battles that had 100% estimated death toll, in which all involved would be killed.
Why, then, do they exist? They serve to hold off Covenant advances until a war-winning solution can be found.
In short, Ackerson's Spartan-III's were only there to trade lives for time.
All in all, those are the Spartans.
Great answer manTj2592 19:26, June 7, 2011 (UTC)