With the partial success of the Spartan II Program, another sector of ONI had theirs eyes set on starting a new Spartan program. They wanted something exponentially cheaper and safer. Engineered by Colonel James Ackerson of the Office of Naval intelligence, the Spartan IIIs were to be the next generation of super soldiers. Similar to the original selection process of the Spartan II program, orphans were selected from the various Human-Covenant based orphanages. Using these vengeful orphans from fallen Colonies, they were to be cheaper to arm, train, and augment. The children were chosen from a larger pool of candidates as to collect more children than in the Spartan II program.
At the point of the Spartan III program becoming a success, ONI went public with the Spartan II program, but to forever keep the Spartan III program a secret to boost morale.
There were teams of Spartan IIIs comprised of incredible soldiers. These special teams were known as Noble Team and the Headhunters. Those of Noble Team were given specialized variants of Spartan II used Mjolnir armor. Headhunters were used as ONI-specialized soldiers equipped with experimental technology eventually used in the ODST and Spartan IV programs.