Osiris was an Orion-class warship in the Colonial Fleet during the First Cylon War. It was part of a secret Colonial fleet hidden deep within Cylon territory. The fleet consisted of colonial ships which were reportedly destroyed in various engagements during the first ten years of the First Cylon War. Individual crew members of the secret fleet were required to witness their own death certificates; even their families were unaware they were still alive. The actual destruction of the ship occurred over the ice planet Djerba, a former colonial winter resort destination. The Osiris was participating in a classified mission believed to be key in bringing about the end of the war. Outnumbered 10 to 1, the Osiris was unable to trigger its nuclear weapons due to damage sustained to its outer launch doors during the opening salvo with the basestar. The Commander of the Osiris ordered the ship crash into the Basestar, upon impact the commander manually triggered the nuclear weapons destroying the Osiris and the Basestar.