Kydomor Forrix - Drop Site Massacre: In response to the treachery of Horus and his betrayal of the Loyalist Astartes in the Sons of Horus, Emperor's Children, World Eaters and Death Guard Legions at Istvaan III, the Primarch of the Imperial Fists Legion, Rogal Dorn, on the direction of the Emperor who had learned of Horus' actions from the Loyalist survivors aboard the Eisenstein, ordered 7 Loyalist Space Marine Legions to Horus' base on Istvaan V to challenge the Traitors. They would attack in two waves and fall under the supreme command of the Iron Hands' Primarch Ferrus Manus. The Legions comprising the first wave were the Iron Hands, Raven Guard and Salamanders. The Legions comprising the second were the Iron Warriors, Alpha Legion, Night Lords, and a large contingent of Word Bearers that their Primarch Lorgar had stationed in the star system. Unknown to Dorn and Ferrus Manus, the Night Lords, Alpha Legion, Iron Warriors and Word Bearers had all turned from their service to the Emperor and secretly pledged their loyalty to Horus. The Warmaster had  instructed those Legions' Primarchs to keep their new allegiance to Chaos a secret.The Iron Hands, Salamanders and Raven Guard were deployed in the first wave of the assault. After they secured the drop site, they were to have been followed by the arrival of the other four Legions. The first wave secured the drop site, known as the Urgall Depression, though at a heavy cost. Horus ordered his front line troops to fall back in a feint, tempting Ferrus Manus to overstretch his already thin lines. Against the advice of Corax and Vulkan, Manus led his Veterans against the fleeing Traitor Marines unsupported. Manus then brought his brother Fulgrim to combat. As the two Primarchs drew their weapons, the Raven Guard and Salamanders fell back to regroup and allow the second wave's Legions to advance and earn glory. The secret Traitor Legions mustered in the landing zone, armed and ready for battle, unbloodied and fresh. The Iron Warriors had claimed the highest ground, taking the Loyalist landing site with all the appearance of reinforcing it through the erection of prefabricated plasteel bunkers.Both the Word Bearers and the Night Lords were to be the anvil, whilst the Iron Warriors would be the hammer yet to fall. The enemy would stagger back to them, exhausted, clutching empty Bolters and broken blades, believing their presence to be a reprieve. Though the Salamanders and the Raven Guard voxed hails requesting medical aid and re-supply, the line of Astartes atop the northern ridge remained grimly silent as the exhausted warriors of the Raven Guard and Salamanders came to within a hundred metres of their allies. It was then that Horus revealed his perfidy and sprung his lethal trap. Forrix willingly took part in this duplicitous slaughter of his former cousin Astartes. As Horus pressed the counterattack he managed to sandwich the Loyalists between the two Traitor forces, killing most of them. Meanwhile, the Iron Hands were cut off and slaughtered to a man -- the Veteran Morlock Terminators cut down and the Primarch Ferrus Manus beheaded by Fulgrim. Nearly two Legions had been all but wiped out in one fell swoop.