Spartan-IIs: Chosen to fit within a specific gene pool that showed exceptional skill in both mental and physical ability, chosen and kidnapped at age 6 to work with Dr. Catherine Halsey on the planet Reach where they trained to become soldiers and received augmentations at age 14 that gave them the approximate ability of an 18 year old Olympic athelete. 33 survided these augmentations with no side effects out of 75. They received their armor later. Spartan-IIIs: Chosen from a larger group to be more economical, they were trained on the planet Onyx and also received augmentations. They were not equal in ability to the Spartan-IIs and did not have shielded armor, but they did have camouflage cloaking plates on their armor.