Siege of Terra (Detailed) 3

Following the fall of the Lion's Gate Spaceport on the 11th of Quintus, the loyalist situation had become dire as most of the Sprawling Magnifica was now in traitor hands. Four key areas were now threatened by the traitors: the Colossi Gate, the Eternity Wall Spaceport, the Saturnine Gate, and Gorgon Bar. Perturabo and Abaddon both noticed a minor flaw in the Saturnine Gate, a small crack in its subterranean barrier that laid along a fault line opened by the intense orbital bombardment. If this could be exploited, the entire inner Saturnine Gate complex could be rapidly captured and allow the Sanctum Imperialis to fall in a matter of weeks instead of months. Meanwhile, Rogal Dorn only had enough resources to hold three of these locations, and reluctantly had to abandon a fourth and its defenders to annihilation. Dorn ultimately chose the Eternity Wall Spaceport, as since they did not command the orbit above Terra such a facility was useless to them anyway. In addition, Dorn suspected Perturabo knew of the flaw in the Saturnine Gate and set a trap there to annihilate the traitors as they attempted to exploit it.[13a] The four battles erupted near-simultaneously.[13a]

At Gorgon Bar, Blood Angels Primarch Sanguinius and Imperial Fists Captain Fafnir Rann oversaw the defenses against a large Iron Warriors-led assault under Yzar Chroniates, Ormon Gundar, and Bogdan Mortel.[13b] During the battle, Sanguinius destroyed a Warlord Titan of the Legio Vulpa by boarding its head and impaling it with the Spear of Telesto. Such was the spectacle that three accompanying traitor Warhound Titans fled from Sanguinius' sight.[13a] Thanks to the inspiration provided by Sanguinius, the traitor assault at Gorgon Bar was broken when the defenders drove the Iron Warriors from the towers of the Fourth Circuit Wall.[13b] At the Colossi Gate, the defenders were led by Primarch Jaghatai Khan, Blood Angels First Captain Raldoron, Marshal Aldana Agathe, and Custodes Captain-General Constantin Valdor. Not wanting to wage a purely defensive war and wishing to eventually retake the Lion's Gate Spaceport, Jaghatai Khan led a 300-strong Jetbike charge from the Colossi Gate that devastated Death Guard-led forces until at the last moment the White Scars withdrew back to their own lines.[13c] Magnus and Ahriman along with a cabal of Sorcerers from the Order of Ruin subsequently launched a psychic assault on the defenders, sapping their will to fight and summoning vast amounts of Daemons including eight gigantic Warhound Titan-sized monsters[13f]. However thanks to the defensive storms erected by Jaghatai Khan's Stormseer's led by Naranbaatar, the loyalists were able to hold the line.[13d]

The Traitor Titan Legion's advance[15]

With the tacit approval of Perturabo, Sons of Horus First Captain Abaddon led a massive assault on the Saturnine Gate, hoping to exploit the flaw observed there. At the Saturnine Gate, three Donjon Pattern Siege Engines led the attack, which consisted of the full strength of the Emperor's Children (some 100,000 Space Marines) under Fulgrim himself.[13d] Meanwhile, Abaddon himself alongside Horus Aximand, Falkus Kibre, and Tormageddon led a spear-tip assault from Mantolith and Plutona assault drills beneath the Saturnine Gate, hoping to exploit the gap. His forces consisted of not only the elite Justaerin and Reaver Attack Squad but also the 18th and 25th Companies under Tybalt Marr and Lev Goshen.[13e] However Dorn was ready for them, and organised a series of kill-teams under Garviel Loken and Nathaniel Garro to ambush the traitors as they emerged from beneath the earth. In addition, Arkhan Land was able to fill the breach with fast-drying sealant, entombing many traitors beneath the walls, including the majority of 25th Company and Goshen. In a series of brutal massacres, the Sons of Horus were beaten back and Aximand, Kibre, and Tormageddon were all slain. Abaddon himself barely escaped with his life after reluctantly ordering a withdrawal. Above, Fulgrim and the Emperor's Children wreaked havoc but the Imperial Fists defenders were able to use their defenses to hold back a force ten times their size. Dorn himself soon arrived, briefly battling Fulgrim before the Phoenician learned the subterranean assault had failed and now fed up with his traitor allies, left the battlefield. However before Fulgrim departed, he summoned his elite guard under Eidolon to kill Dorn. The Primarch alongside Sigismund were able to defeat Fulgrim's assassins as the Emperor's Children retreated after taking 18,000 casualties.[13e] Fulgrim and the Emperor's Children had grown bored of the stalemate and set off on a bloody orgy against the people of Terra of such depravity and destruction that ten thousand years later, Terrans are still distrustful of Space Marines.[1c]

Despite the decisive victory at the Saturnine Gate and the defensive successes in holding Gorgon Bar and Colossi, just as Dorn predicted the Eternity Wall Spaceport was doomed. Defenders in the area were led by Imperial Fists Captain Camba Diaz, White Scars Captain Shiban Khan, High Primary Solar General Saul Niborran, and Sisters of Silence Commander Jenetia Krole. The commanders knew that Dorn had no intent of reinforcing them, but not wishing to abandon their doomed troops did not evacuate. Camba Diaz died slaying scores of traitors on the Pons Solar bridge, refusing to take a step back.[13f] Shortly after Angron himself arrived, and in a moment of clarity requested the surrender of Space Port. Niborran and his Imperial Army troopers responded by blasting Angron to pieces with the Port's gun batteries, though the traitor Primarch quickly regenerated.[13g] Niborran and his men alongside Krole all fought to the death against a savage World Eaters assault led by Angron, Kharn, and Khornate Titans. Shiban Khan was thought slain in a shuttle crash while trying to help the last Imperial Army troopers under his command evacuate. Meanwhile at the edge of the Sol System, a contingent of 10,000 Dark Angels under Captain-Paladin Corswain arrived to help defend Terra.[13e]

Magnus' Infiltration

Shortly after the traitor setback at Saturnine, Magnus the Red made his move to recover the lost shard of himself inside the Imperial Palace. Launching all 9,000 Thousand Sons under his command at the Western Hemispheric region of the Palace, the traitors also utilize waves of Beastmen, Battle-Automata, as well as a Capitol Imperialis. In the ensuing furious battle, the Thousand Sons Capitol Imperialis Khasisatra was badly damaged by the Palace Guns, but before it could explode Magnus himself entered the fray and enclosed it in a stasis bubble. Magnus then psychically hurled the Khasisatra into the walls before dissipating the stasis bubble, creating a catastrophic explosion equal to 12 Atomic Weapons that caused a large breach to form in the Western Hemispheric Wall. Ahriman and 200 Thousand Sons then led an assault into the breach, but at the last minute were apparently driven back.[14]

In truth, Magnus had just used the attack as a distraction for himself, Ahriman, Amon, Menkaura, and Atrahasis to infiltrate the Palace. Moving through the Great Observatory and then the Hall of Leng, Magnus seemingly slew Malcador in a rage at a subterranean lake after being told his lost shard was now out of his reach. Now intent on killing the Emperor, Magnus and his troops infiltrated into the Imperial Dungeon and came before the Golden Throne. The Emperor offered Magnus a chance to return to the loyalist side, but the Crimson King refused after being told he would have to condemn his Thousand Sons to destruction due to their rampant mutations. Magnus attempted to slay the Emperor but was stopped by Vulkan, and the two Primarchs engaged in a vicious duel that eventually saw the loyalist son prevail thanks to the sacrifice of Igen Gargo. Before Vulkan could deliver the final blow Magnus fully gave himself to Chaos and was expelled from the Palace alongside his sons by the Palace's anti-Daemonic wards.[14a] After the incident, Magnus fully gave himself to Horus' cause. Meanwhile, Malcador was resurrected by Alivia Sureka at the cost of her own life.[14b]

The Palace Besieged

By the twenty-seventh of Quintus, Horus' forces had captured both the Lion's Gate and Eternity Wall Spaceports. This allowed him to fully land his last and greatest reserves: the Legio Mortis Titan Legion. By this point in the battle, however, acting siege commander Perturabo had become fed up by the state of the traitor armies. Daemons swarmed the ranks of the traitor armies of his brothers and allies had now pledged themselves fully to the Ruinous Powers. Seeing that the war was no longer one of Legion vs. Legion, Perturabo's breaking point came when Horus ordered him to break up his Legion and disperse it amongst the greater traitor armies. Mortarion and the Death Guard would instead take up Perturabo's positions, and the humiliation proved too much for the Lord of Iron to tolerate. Fed up, he ordered his Legion to leave Terra for paths unknown. The Iron Warriors began to evacuate Terra, causing great mayhem in the blockading Traitor fleet.[15a] Some Iron Warrior contingents refused to abandon the campaign or were just left behind by their comrades, and would keep fighting on Terra until the end.[22a][29] Meanwhile due to the machinations of the Daemon Vassukella, who had infected the Astronomican, waves of madness swept across the loyalist lines and caused many mortal defenders to commit suicide or abandon their posts. Those who abandoned their posts marched towards "Paradise", in truth a horrific dream-farm erected by the Emperor's Children.[15c]