Nassir Amit - Age of Darkness: If the Great Crusade was Mankind's finest hour, then the Horus Heresy was surely its blackest. Brother fought brother, with quarter neither offered nor given. Heroes were slain, worlds burned and the Emperor's dreams of peace were shattered forever. In the midst of this darkness, the Blood Angels never wavered, but held true at the Emperor's side.Sanguinius now stepped into the void left by Horus' desertion, assuming command of the Emperor's loyal forces. In doing so, he thrust the Blood Angels into the brutal forefront of the fighting. The rivalry of the Blood Angels with the World Eaters now escalated into bitter enmity as the two Legions found themselves serving different masters, and their confrontations were to be amongst the bloodiest and hardest fought of that bloodiest of wars.It is said that Horus hated and feared Sanguinius more than any of his brothers and wove many strategies to ensnare or slay him, though all failed. For all the might of the Emperor, for every effort of Sanguinius and the remaining Loyalist primarchs, the forces of Horus drove all before them.In too short a time, the Emperor of Mankind was assailed within His great Imperial Palace on Terra in 014.M31 during the Siege of Terra. When the imminent arrival of the Space Wolves, Dark Angels and Ultramarines Legions forced Horus to gamble on forcing a final battle with the Emperor by dropping the Void Shields protecting his battle barge, the Vengeful Spirit, Primarchs Sanguinius, Rogal Dorn of the Imperial Fists, and the Legio Custodes joined the Emperor in a daring teleport assault upon the vessel. As Sanguinius possessed the psychic ability of precognition, it seems almost certain that he knew he was going to his own death. It remains unknown whether fatalism or simple loyalty to his father brought Sanguinius aboard. The Blood Angels themselves have no doubt on the matter.The two primarchs and former brothers finally met on the command deck. In evil cunning, Horus offered Sanguinius a position of power if he would renounce his loyalty to the Emperor, and Sanguinius refused. Thus rejected, Horus flew into a rage and attacked. Even at the peak of his powers, Sanguinius could not have hoped to prevail against the monster Horus had become, and the primarch was weary and wounded from his travails on Terra.Despite his grievous wounds, Sanguinius managed to match Horus' martial prowess, even at the height of his Daemonic power as the greatest mortal champion of Chaos Undivided, and Horus was forced to deal with the Angel by psychic methods. In his limitless malice, Horus made sure that Sanguinius' death was the most painful and foul that the boundless evils in his service could administer.The Warmaster's psychic assault was so powerful, it echoed down through the generations of Sanguinius' gene-sons who are haunted by its echo within their souls to this day, as the Blood Angels were forced to draw new genetic samples from their primarch's corpse after his death because of the loss of gene-seed stocks they had incurred during the Heresy. The result was the imposition of a new curse upon later generations of Blood Angels -- the Black Rage.When the Emperor at last entered Horus' sanctum, He found His rebellious Warmaster standing above Sanguinius' broken, bleeding corpse. In the battle that followed, Horus was finally vanquished, though the Emperor too was cast down near to death. There are many tales told of this final battle and, though the exact facts are long lost, one detail holds through all the recitations through all the millennia since. Despite the Emperor's great power, He could never have bested Horus had not the blade of Sanguinius wrought a chink in the Warmaster's armour, and because of this, the Blood Angels claim him to be the greatest of the primarchs.