The Immigrant Fleet is an organization that wishes to control the Zohar. In Episode II, the Immigrant Fleet is led by a man called Sergius XVII, who is also the leader of Ormus. It serves as the public persona of the highly secretive Ormus.
Highly religious and powerful, the Immigrant Fleet claims to have been the guardian of the Zohar "since time immemorial." The Immigrant Fleet was involved in the Miltian Conflict and the space-time anomaly that sealed off Old Miltia. The Immigrant Fleet's military arm, U-TIC, gained access to the Y-Data that Joachim Mizrahi left behind, employing both political maneuvers and outright brute force. Though they succeeded in unlocking the way to Old Miltia, the Immigrant Fleet suffered a major defeat when the Zohar and the Omega System were activated, which destroyed the Immigrant Fleet forces as well as the Federation and Miltian taskforces sent to stop them. The Patriarch himself was later eliminated by the Testaments after being abandoned by his Ormus subordinates. On another interesting note, the Database in Episode III identifies the Gnosis under the related name, the Pilgrimage Fleet.