The responsibilities and purposes of a Legion seem to vary. They are capable of performing tasks ranging from bridge-crew on starships to ground combat.
The violent nature of the Elite society likely demands that Legions should be capable of engaging in varied forms of combat.
A Warrior Crèche is likely a type of Legion where newer warriors hone their combat skills before being assigned to a regular legion. Warrior crèches seem to be specifically used for ground combat, and are carried aboard Covenant Fleets should any ground actions be needed.
- The term Legion was originally used to describe an infantry unit in Ancient Rome; the general size of these units fluctuated during the military history of the Roman Empire between approximately 4500 and 5200 soldiers.