Great Crusade - Expeditionary Fleets: During the Great Crusade, the vast forces of the Emperor were organised into a number of different formations which became known as the Expeditionary Fleets. At first there was but one fleet, the Principia Imperialis -- commanded by the Emperor Himself -- but as the Crusade spread across the galaxy more and more were launched. Trusted and powerful generals were appointed to lead these new fleets.Later, after the discovery of several of the Primarchs in the early stages of the Crusade, the Imperial fleets were divided into three main thrusts across the galaxy, one commanded by Horus, the other by Ferrus Manus, and the last by the Emperor Himself.In order that they could be effectively supported and their movements across the galaxy tracked with some degree of accuracy, each of the Expeditionary Fleets was designated a number by the War Council. As the Great Crusade drew to a close in the early 31st Millennium, some 203 standard years after it began, there were 4,287 primary Expedition Fleets engaged upon the business of enforcing Imperial Compliance and extending the Imperial aegis across the galaxy as well as 60,000+ secondary deployment groups involved in regulating Compliance or Imperial occupations. A further 372 Expedition Fleets were regrouping or refitting in the Sol System or other Imperial hub star systems or resupplying as they awaited new orders.The composition of each of the fleets was not fixed. The various fleet groups, Imperial Army regiments, auxiliary troop formations and even Space Marine Legions that made up a fleet could come and go over time, as prevailing strategy dictated. But the designation numbers remained and, while most never held any particular significance, some became famously associated with specific Primarchs or other prestigious leaders of the Imperium.The numerical designation of an Expeditionary Fleet was also applied to worlds conquered by its forces -- for example the Imperial world initially known as 63-19 was the nineteenth world discovered by the Warmaster Horus' 63rd Expedition. It was therefore possible for the Imperium's administrators to plot the movements of a specific fleet by the worlds it encountered, in chronological order.While all of the original Expeditionary Fleets had been assembled in Terran space by the Mechanicum, by the height of the Great Crusade they had been dispersed throughout the Milky Way Galaxy to reunite all the human-settled colony worlds under the Emperor's rule to bring to fruition His dream of a united human race dominating the stars. The Expeditionary Fleets were given a broad remit to bring human-settled worlds into the Imperium by diplomacy if possible but by force if necessary, and to cleanse any xenos species from the galaxy who represented a threat to humanity.As almost all intelligent alien species encountered by Mankind had proved hostile, outright genocide was the usual expected remedy. The fleets were also tasked with the secondary mission of exploring the galactic wilderness following the terrible anarchy of the Age of Strife so that new frontiers could be opened for human settlement and resource extraction in formerly virgin regions of the galaxy.While the Emperor hoped that most human civilisations would willingly accept reunification under the Imperial aegis because of all the benefits interstellar unity offered, He knew that many human worlds would forcefully reject Imperial Compliance. As such, each Expeditionary Fleet was a potent military armada usually under the overall command of a high-ranking officer of the Imperial Army who bore the rank of Lord Commander and the expedition's fleet elements were commanded by an officer with the rank of Master of the Fleet. Additionally, each of the Emperor's Primarchs was given command of an unusually large Expeditionary Fleet, to which was attached the main body of their Space Marine Legion as well as substantial starship and Imperial Army assets.These Expeditionary Fleets, which were quite rare since the majority of the Great Crusade's fleets possessed no Astartes contingent at all, usually undertook the major thrusts into completely new areas of the galaxy. Smaller fleets with less combat capacity would then follow in a major fleet's wake, branching off to ensure Imperial Compliance on worlds that presented less human or xenos resistance than those faced by the fleets carrying Astartes complements.However, the Primarchs of several of the Legions were known at times to split off smaller units of Space Marines from their main fleets to accompany Expeditionary Fleets that were otherwise lacking in Space Marine support. In such situations, the ranking Space Marine officer served as the fleet's Lord Commander since Astartes always assumed command over normal troops in any military situation where they were present during the Great Crusade. What follows here is a list of the few Expeditionary Fleets of the Great Crusade that have been recovered from ancient Imperial records.