Liber Astartes

The Space Marine Legions of the 31st Millenium field a diverse and formidable range of genetically-enhanced warriors and advanced war machines, superior to any other military force in the galaxy. As an Age of Darkness falls across the stars and the fires of rebellion rage out of control, the armies that were used to forge the Imperium turn upon each other in an apocalyptic civil war - the Horus Heresy.