Event · M31

Siege of Terra

The Siege of Terra was the ground assault on the Imperial Palace that formed the climactic final battle of the Horus Heresy, fought in 014.M31. It followed the Solar War, the separate campaign of fleet actions through the Sol System’s defences; where that struggle is treated as its own event, the Siege of Terra denotes the land battle for the Palace itself, waged between the Traitor forces of the Warmaster Horus Lupercal and the Loyalist defenders commanded in the Emperor of Mankind’s name by Rogal Dorn, primarch of the Imperial Fists. The assault followed the Drop Site Massacre on Istvaan V, in which Horus had crippled three Loyalist Legions, and the subsequent Solar War, in which the Traitor fleets forced passage past Luna, the Martian approaches, and the system’s orbital defence grid to achieve planetfall on Terra. Rogal Dorn, appointed to organise the Throneworld’s defence, drew the Imperial Fists, the Imperial Army, and Mechanicum forces including Titan Legions and Legio Cybernetica into a layered defence around the Imperial Palace, while the Emperor withdrew into the Sanctum Imperialis to labour upon the Golden Throne. Reinforcement came late: the White Scars under Jaghatai Khan and the Blood Angels under Sanguinius reached Terra in time to join the fighting, though other Loyalist Legions remained too distant or engaged elsewhere to take part. Once ashore, Horus’s Traitor Legions, among them the World Eaters under Angron and the Death Guard under Mortarion alongside the Sons of Horus, Emperor’s Children, and Iron Warriors elements, breached the Palace’s outer defences at several points, including the Lion’s Gate, and fought onward through the Eternity Gate toward the Sanctum Imperialis. The Legio Custodes under Constantin Valdor and the Sisters of Silence held the Sanctum Imperialis alongside the massed Imperial Army, and Sanguinius led the Blood Angels and other Loyalist reinforcements into the fighting. The siege reached its climax when Horus Lupercal and the Emperor met in single combat aboard the Vengeful Spirit, then anchored above the Palace; Sanguinius died in the same engagement, and the Emperor, though victorious, was left mortally wounded, and Horus’s death broke the cohesion of the Traitor forces. The Emperor’s survival, and his subsequent interment upon the Golden Throne, is recorded as a direct consequence of injuries sustained in this combat, marking the transition from his active rule to the long regency that defined the later Imperium. With the Warmaster dead, the Traitor Legions broke and withdrew from the Sol System, ending the Heresy as an organised war even as its consequences went on to shape the Imperium for the following ten thousand years. The Siege of Terra stands as the culmination of the sequence that runs from the Solar War through the Battle at the Eternity Gate to the Death of Horus, and is linked in turn to the War in the Webway, the psychic undertaking the Emperor had pursued before the Heresy forced his hand. Alongside the Emperor’s earlier unification of Terra, it anchors the Sol System’s timeline at the Heresy’s end. By the Siege of Terra, as Typhus, he worked with Perturabo, Ezekyle Abaddon, and Zardu Layak to summon Cor’bax Utterblight into the Imperial Palace, and took part in the assault on the Colossi Gate against forces led by Jaghatai Khan, Constantin Valdor, and Raldoron. Mortarion then sent him to retake the Astronomican from Corswain’s Dark Angels. After Jaghatai Khan’s attack on the Lion’s Gate spaceport banished Mortarion, Typhus took command of the Death Guard on Terra, rallying Caipha Morarg and Zadal Crosius, and his assault reached the Hollow Mountain, where it was opposed by forces of the Dark Angels and of Sigismund; a prayer led by Euphrati Keeler produced a psychic backlash that drove the Death Guard back and reactivated the Astronomican. A separate account holds that, while Mortarion led the assault on the Lion’s Gate spaceport, Typhus commanded the Plaguefleet. Vulkan, primarch of the Salamanders, was present at the Siege, his survival kept secret from all but a few. Having reached the Imperial Palace through the webway, he installed in the Golden Throne the Talisman of Seven Hammers, a device of his own making able to destroy Terra should Horus prevail. When Magnus the Red infiltrated the Imperial Dungeon with Ahriman, Amon, Menkaura and Atrahasis to kill the Emperor, Vulkan blocked his blow and fought him; one of Vulkan’s warriors died shielding him, a sacrifice recorded variously as that of Barek Zytos or of Igen Gargo, and Magnus, giving himself wholly to Chaos, was expelled by the Palace’s wards. Malcador later sent Vulkan into the webway, where in the Impossible City he confronted Magnus, who was draining the Emperor’s strength through a psychic ritual. Magnus killed him repeatedly, but Vulkan regenerated each time and struck off Magnus’s head with his hammer Urdrakule, banishing him to the warp. That defeat, together with Sanguinius’s banishment of Angron, broke the traitor advance short of the Eternity Gate. When the Emperor left to board the Vengeful Spirit, Vulkan remained at the Golden Throne to oversee the Talisman; he began to activate it as the traitors reached the throne room, desisted on hearing Actae’s broadcast that the Emperor still lived, and was present when the Emperor’s broken body was placed upon the Throne. Leman Russ of the Space Wolves was largely absent from the Palace fighting itself. After Prospero and the Alaxxes Nebula he had reached Terra, helped Malcador organise the Knights-Errant strike against Horus at Molech, and then left again with his Legion to hunt the Warmaster, against the wishes of Rogal Dorn and Sanguinius, who wanted him to remain for the coming siege. He wounded Horus at Trisolian and was himself crippled; the Wolves’ subsequent ordeal at Yarant kept him from the Throneworld during the main assault. Russ and Lion El’Jonson arrived at Terra with Guilliman’s relief fleet immediately after the Siege’s climax, once the Emperor had already been mortally wounded aboard the Vengeful Spirit. On learning what had befallen the Emperor, Russ quarrelled verbally with Constantin Valdor, who held that events had followed the Emperor’s design; he and the Lion later quarrelled again beneath the Palace, after which both appeared without lasting injury. Russ then sat on the Grand Council of Reconstruction and pressed, with Dorn and the Lion, for immediate pursuit of the fleeing Traitors. Perturabo, primarch of the Iron Warriors, held a pivotal command in the Siege. At first denied the assault on the Palace and ordered to fortify the Sol System against Guilliman’s expected arrival and to clear landing zones for the Traitor Titans, he was later entrusted with the main offensive against the Lion’s Gate Spaceport, which he took after sacrificing Forrix’s force as a feint so that the Iron Blood could dock with the spaceport’s spire; there he declined Rogal Dorn’s challenge to single combat. From a command centre on Terra’s surface he then directed the Traitor war effort through a staff that included Abaddon, Ahriman, Typhus and Eidolon, allowing Abaddon and the Emperor’s Children to attack the Saturnine Gate, where Dorn’s ambush awaited them. When Horus ordered him to disperse his Legion among other warzones and cede command to Mortarion, Perturabo withdrew the Iron Warriors from Terra to the Iron Blood, from which he followed the Siege’s final actions off Mars. Rogal Dorn held overall command of the Palace defence throughout the Siege, directing the war first from the Bhab Bastion with a largely human staff and later from the Sky Fortress. He forbade Sanguinius and Jaghatai Khan at first from leaving the walls, then opened the Helios Gate so that Sanguinius could lead a counter-attack to rescue Army conscripts outside. At Saturnine he recognised a flaw Perturabo might exploit, set a trap, and in person fought Fulgrim of the Emperor’s Children, landing mortal blows that the daemon primarch regenerated; Fulgrim quit the field after learning that Abaddon’s subterranean assault had failed, and Dorn with Sigismund survived the subsequent attempt by Eidolon’s elite to assassinate him. When the Bhab Bastion itself fell to a Sons of Horus assault hours after Sanguinius’s stand at the Eternity Gate, Dorn conducted a fighting withdrawal into the Sanctum Imperialis before joining the teleport strike aboard the Vengeful Spirit. Among the Emperor’s Children on Terra, Fabius Bile established a bunker laboratory in which he experimented upon captured civilians and pursued further attempts to enhance Space Marines and to clone primarchs, even as the siege continued above. Disgusted by the Warp powers unleashed in the battle’s last stage, he left Terra with a retinue of altered followers before Horus’s death; Fulgrim is recorded as placing a bounty on his head for that departure. Khârn of the World Eaters fought through much of the Siege. Before the landings, aboard the Conqueror, he confronted Angron when the primarch, enraged that the Death Guard would assault Terra first, began killing his way through the ship; Khârn was overpowered, but he fixed a teleport homer to Angron that sent him into the shifting maze aboard the Night Lords flagship Nightfall. On Terra he led an attack from a Spartan assault tank on the Lion’s Gate spaceport that faltered against the Emperor’s psychic shield, and in the renewed assault he fought beside Abaddon, Kroeger, and Zardu Layak and duelled Sigismund until Rogal Dorn struck him aside; a rescue launched by Abaddon saved him. With Angron he then led the World Eaters assault on the Eternity Wall spaceport, where he killed Jenetia Krole of the Sisters of Silence without recognising her. In the drive into the Inner Palace he was at the forefront of the assaults until Sigismund, who refused to speak to him, killed him in a duel. Apothecary Kargos had his body carried back to the Conqueror, and after the Traitors withdrew from Terra he was found to be alive, though comatose.

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