In 2491, the Office of Naval Intelligence re-instituted the Orion Project, an attempt to create engineered super-soldiers to boost combat effectiveness. Though the initial class in 2321 ended in complete failure including the death of all five candidates, the second class was far more successful, beginning with 65 candidates and later expanding to 165 and eventually 300 total members at its peak. During their time in the project, the candidates received numerous physical augmentations, and were sent on various missions throughout the pre-war insurrection, including Operation: CHARLEMAGNE and Operation: TREBUCHET.
Though effective, the project was eventually cancelled in 2506 due primarily to the side-effects displayed by the candidates, including physical and signs of mental illness. The remaining candidates were all reassigned to other special operations units, though many were forced into early retirement from the service due to the severity of their condition. A few, most notably candidate Avery Johnson, continued service for far longer than even an unaugmented soldier, serving for well over forty years until his death in 2552 at the age of around 70.
The mixed results of the Orion Project would lead Doctor Catherine Halsey to determine that the best way to eliminate the negative effects on the candidates was to only use children for training and augmentations, a tactic she utilized in the Spartan-II program. This thinking proved to be correct, resulting in Spartan-II supersoldiers who were able to fight far longer and without loss in combat effectiveness for far longer than just about every Orion Project member.