Archived: Expeditionary Fleets

An Expedition or Expeditionary Fleet was the standard Imperial exploratory spacefaring force during the Great Crusade.

Overview
Originating from Terra, the Imperial Expeditionary Fleets dispersed all over the galaxy, carrying out the Emperor's vision of uniting known space under the banner of Humanity. Expedition Fleets had a wide remit. Their primary mission was to find lost human colony worlds and bring them into the bosom of the Imperium. Secondary missions involved the exploration of space, the cataloging of everything found, the claiming of resources in the name of the Emperor and the elimination of any alien threats

The unification of human worlds did not always proceed without incident, as not all lost worlds showed immediate interest in making themselves subservient to the Imperium. In these cases, compliance with Imperial directives was enacted with the use of military force. These situations, as well as the ever-present alien threat, resulted in Expedition Fleets having a strong armed contingent, and were usually under the command of a military officer of the Imperial Army, a Lord Commander. In addition to a Lord Commander, each Expedition had a Master of the Fleet who was in charge of the Imperial Navy ships in the Expedition. Each of the Primarchs was able to, and often did, command an Expeditionary Fleet, attaching to it the majority of their Legion. Most Fleets had no Astartes presence at all, although some Primarchs split their Legions into small detachments that they parcelled out to various expeditionary forces.

Known Expeditionary Fleets
In the 203rd year of the Great Crusade, War Council logs indicated that there were:
 * 4,287 expedition fleets engaged in active exploration
 * 372 expedition fleets engaged in refit and repair
 * 60,000 (approx.) detached compliance groups involved in occupation and colonization.