Solomon Demeter - Istvaan III Atrocity: The terrible campaign that marked the start of the Horus Heresy and was known to later generations as the Istvaan III Atrocity began when the Imperial Planetary Governor of Istvaan III, Vardus Praal, had been corrupted by the Chaos God Slaanesh whose cultists had long been active on the world even before it had been conquered by the Imperium. Praal declared his independence from the Imperium, and had begun to practice forbidden Slaaneshi sorcery, so the Council of Terra charged Horus with the retaking of that world, primarily its capital, the Choral City.This order merely furthered Horus' plan to overthrow the Emperor. Although the four Legions under his direct command -- the Sons of Horus, the World Eaters, the Death Guard and the Emperor's Children -- had already turned Traitor and pledged themselves to Chaos, there were still some Loyalist elements within each of these Legions that approximated one-third of each force; many of these warriors were Terran-born Space Marines who had been directly recruited into the Astartes Legions by the Emperor Himself before being reunited with their Primarchs during the Great Crusade. Horus, under the guise of putting down the rebellion against Imperial Compliance on the world of Istvaan III, amassed his troops in the Istvaan System. Horus had a plan by which he would destroy all of the remaining Loyalist elements of the Legions under his command.Like many of his fellow Legionaries, Demeter had unknowingly been marked for death as an Imperial Loyalist, and was fated to launch with the first wave under the pretense of bringing Istvaan III back into the Imperial fold. Initial attacks on the Choral City had washed away any feelings of unease, the release of the Loyalists' anger and hurt in bloodshed reassuring them that things were as they should be, and that their earlier misgivings about the directions of their Legions were no cause for concern.But then Captain Saul Tarvitz had arrived on the planet's surface with an incredible tale of betrayal and imminent attack. Many had scoffed at Tarvitz's warning, but some had immediately known the truth of it, and had fought to make their brothers realise the imminent danger. As the monstrous scale of the betrayal sank in, the Loyalist Sons of Horus, World Eaters and Emperor's Children Astartes had raced to find shelter before the deadly viral payload struck the world intended to be their tomb. Demeter was badly wounded in the firestorm that followed the initial virus bombing by the hideous Life-eater pathogen.The first solar month of the battles that followed the failed Virus Bomb attack had passed in a blur of agony and nightmares. Demeter's life had hung in the balance until Saul Tarvitz had come to him and promised that he would make the Traitors pay for their betrayal. Seeing the fires of ambition finally lit within the young warrior had galvanised Solomon, and his recovery had been nothing short of miraculous. An Apothecary named Vaddon had found time, between treating the wounded, to bring him back from the brink of death, and as the conflict ground onwards, Demeter found his strength returning to the point where he was able to fight once more.Taking the armour of the dead, Demeter had risen, phoenix-like, from what many had considered to be his deathbed, and had fought on with all the ferocity and courage for which he was renowned. Saul Tarvitz had immediately offered to transfer command of the Loyalist Emperor's Children to him, but he had refused, knowing that the surviving warriors of all the Legions looked to Tarvitz for leadership. To usurp that would be pointless, especially now that their heroic defiance of betrayal was almost at an end.Ultimately, Demeter would be betrayed unto death by one of his own Battle-Brothers. Captain Lucius' pride and jealousy had eventually overwhelmed him as the young Emperor's Children officer had come to resent Tarvitz's role in the Loyalists' success against the enemy and the respect he commanded from the other Loyalist Astartes. Lucius secretly contacted Lord Commander Eidolon and promised to deliver Tarvitz and break the Loyalists' defences at the Precentor's Palace for Horus in return for being accepted back into the Legion.Eidolon accepted the proposal. As Lucius slaughtered a group of 30 Loyalist Astartes who were defending the Loyalists' flank to open the way for the Traitors' final assault against their former brethren, he was aided, unknowingly, by Captain Demeter who thought Lucius had been under assault by Traitors. Realising he had been tricked, Demeter realised with horror the full extent of his mistake and Lucius' betrayal. Demeter felt the walls of his existence come crashing down as the enormity of what he had done sank in. He dropped to his knees, and tears of horror and anguish spilled down his cheeks.The traitorous swordsman had taken Demeter's honour from him. He flew into a rage, attacking Lucius, wrapping his hands around his foe's neck. But Lucius reacted quickly and impaled Demeter in his stomach with his sword, and tore upwards through the senior Astartes' chest, as the swordsman thrust his blade completely through Demeter's torso. Demeter fell to the ground, his life's blood seeping into the blackened ground, mortally wounded.As Demeter lay dying, with a clarity denied him in life he saw where Horus' terrible betrayal of the Emperor would inevitably lead, the horror and the long war that would follow. In the wake of this final bit of wisdom, Solomon Demeter died in the darkness of the Precentor's Palace on Istvaan III, an early casualty of the most terrible war in human history.