What the feth? Where the fethin' warp are we?

- Sergeant Hieronymous Strab, T+19 minutes

In the fourty-first millennium, there is only war. Most of these wars, while important to the individuals concerned, have little or no effect on the galaxy as a whole. One specific war, however, was of great concern to the Imperial historians.

This war was one so far in the past as to be almost forgotten, and it was only through a series of apocryphal books, allegedly the accounts of veterans of the human side of the war, that any knowledge was at all retained. The five combatants concerned were all humans (one alien alleged to part of the group was dismissed as a primitive version of a 'deus ex machina', a way to explain certain events that were presumably only documented after the effect), and had unlocked primitive psychic powers, such that they were able to take the forms of other beings. They, using these abilities, were able to save the human race from an alien infestation known as the "Yeerks". However, one discrepancy had emerged. The xenos concerned had apparently had a large empire, such that they were unable to be truly beaten by the humans, only prevented from capturing Holy Terra. Strangely, when records of the truly ancient xenos known as Eldar were examined by Inquisitors of the Ordo Xenos, there was no mention of such a race ever having existed.

Some historians theorised that the accounts concerned were in fact a fictional series, as noted by the apparent single author, the same for all the accounts, despite the different characters who narrated the books. This was countered by the other popular theory which held that the 'author' was merely taking the credit for the resistance group, known as the "Animorphs" for their morphing capability, while the books were all written by the narrators in question. One far more disturbing question regarded the beings known as the Ellimist and the Crayak. These apparently god-like beings had much in common with the Chaos gods Khorne and Tzeentch. Worse still was that the humans appeared to be supporting the Tzeentch-like being.

This would have been merely a piece of trivia, almost as important as the Tanith 1st victory on Monthax, had it not been for the warp storm of 9339487.M41. While this was not a momentous warp storm for the greater universe, it did unfortunately result in the disappearance and presumed destruction of the 365th regiment of Bellis XIV, which resulted in the Imperial forces on Cadia being harder pressed during the 13th Black Crusade.

For nearly all of the eight thousand fighting men of that regiment, it was indeed the end; a failing Gellar field had allowed daemons and other warp entities to board the vessel. Only two squads survived the encounter, being able to hold out in their troop ship's armoury until the warp engine, having detected the failure of the Gellar field, finally cut out. However, while they were alive, they had not reached safety yet. The troop ship emerged from the warp virtually destroyed; all that survived was the armoury section. While it was not designed to enter the atmosphere, the surviving armour plating around this remaining section was happily large enough such that they would not burn up in the atmosphere of any planet they might enter. They still had inertia, and propelled by their momentum, the broken section of ship managed to survive passage through a battle between two battleships and a horde of fighters, and was in fact seen by one of these fighters. As this fighter was watching, another shot it in the rear section and sent it spiraling into the atmosphere, and now following this new arrival.

This is where our story begins. It is the third millennium, and there is only war.