Unlike the current Adeptus Astartes, who serve the Imperium of the late 41st Millennium as a planetary assault and rapid strike force, the Space Marine Legions were the primary frontline military forces of the ancient Imperium of Man. This initial Founding happened before the start of the Great Crusade that reunited the scattered worlds of Humanity beneath the banner of the Imperium of Man, while the Unification Wars were still raging on Terra.Īt the start of the crusade, as the Legions were placed at the forefront of the Imperial expeditionary fleets that left Terra, the Astartes were renamed Space Marines and their formations the Space Marine Legions.
The Space Marine Legions, or the Legiones Astartes in High Gothic, were the original unit formations of the Space Marines created during the First Founding by the Emperor of Mankind on Terra in the late 30 th Millennium.