The Expeditionary Fleets
“In hoc signo vinces – In this sign you shall conquer.” – The Emperor of Mankind presenting the Imperial Eagle to the III Legion Astartes.
An Expedition or Expeditionary Fleet is the standard Imperial exploratory spacefaring force of the Great Crusade.
Originating from Terra, the Imperial Expeditionary Fleets has dispersed all over the galaxy, carrying out the Emperor’s vision of uniting known space under the banner of Humanity. Expedition Fleets has a wide remit. Their primary mission is to find lost human colony worlds and bring them into the bosom of the Imperium. Secondary missions involves 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 does sadly not always proceed without incident, as not all lost worlds shows immediate interest in making themselves subservient to the Imperium. In these cases, compliance with Imperial directives are enacted with the use of military force. These situations, as well as the ever-present alien threat, has resulted in Expedition Fleets having a strong armed contingent, and they are usually under the command of a military officer of the Imperial Army, a Lord Commander. In addition to a Lord Commander, each Expedition has a Master of the Fleet who is in charge of the Imperial Navy ships in the Expedition. Each of the Primarchs is able to, and often does, command an Expeditionary Fleet, attaching to it the majority of their Legion. Most Fleets has no Astartes presence at all, although some Primarchs split their Legions into small detachments that they have parcelled out to various expeditionary forces.