The Obsidian Corps was created as the armed wing of the "Ethfas Protective Squadron", and gradually developed into a multi-ethnic and multi-national military force of Greater Cerberussy. The Obsidian Corps serves alongside the Imperial Army but was never formally a part of it. Initially membership was only open to people of Cerberussian or Yat origin. In 2321, the Maharaja authorized the formation of units composed largely or solely of foreign volunteers and conscripts. Foreign OC units were made up from recruits in Ightilia, Independent Cities of Iteyos-Tekinos, Varina, Yatland and all ethnic minorities in Greater Cerberussy, although groups considered by Ethfases to be "sub-human" such as Whites remained excluded.