The brain-child of Col. James Ackerson, based on intelligence stolen from Dr. Catherine Halsey's personal files on the Spartan II project. Kept secret from even Dr. Halsey herself, Spartan III's were trained on the planet Onyx under the tutelage of a Spartan II. Designed for high-risk, suicide missions, Spartan III's were cheaper to produce, quicker to to train, and ultimately considered expendable for the sake of their mission. Before the destruction of the planet, four generations of Spartan III's were trained and implemented in high-risk missions.
 Alpha Company
Starting their training between the ages of four and six, Alpha Company was made up entirely of orphans from the human-covenant war. The 300 Spartan III's in Alpha company were sent on missions six years into training and augmentations, and eventually suffered 100% casualties during operation PROMETHEUS, in which Alpha Company destroyed a Covenant shipyard.
 Beta Company
Having been given more drastic augmentations than Alpha Company, in order to adapt to the high-risk missions they would be sent on, the Spartan III's from Beta Company were activated when they were only twelve years old. Of the 300 Spartan III's in Beta Company, Only two survived Operation TORPEDO, in which Beta Company destroyed a Covenant refinery and refueling station in the fringes of human-controlled space. The two survivors, Tom-B292 and Lucy-B091, who lost her ability to speak as a result of the aforementioned mission, became trainers of the next class of Spartan III's.
 Gamma Company
Due to increased research into bio-augmentation and genetic manipulation, all 330 candidates for Gamma Company survived to become Spartan III's. Shortly after the augmentation and activation process was finished, the Onyx Sentinels were activated, and the teams that were on the planet were forced to fight against them as Dr. Halsey, Tom, Lucy and a few other Spartans escaped into the Onyx Shield World.
 Delta Company
Having never gotten past the candidacy phase, the fate of the Delta Company candidates is unknown.
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