Dark Imperium trilogy

Dark times have come to the galaxy. Cadia has fallen, destroyed by the onslaught of Chaos. The Great Rift has torn open the warp, spilling forth demons and horrors from its depths. But all hope is not lost… A long-absent hero has returned, bringing with him the wrath of the reborn Ultramarines. Roboute Guilliman has risen to lead the Imperium out of the darkness on a crusade unlike any seen since the fabled days of the Emperor.