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Siege of Terra

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Targetdrone.gif This article is about the Horus Heresy Battle; for the novel series, see The Horus Heresy: Siege of Terra.

"He has come to face his father. That is the purpose of this attack."

Siege of Terra
The Emperor of Mankind battles Warmaster Horus Lupercal aboard the Vengeful Spirit.
Conflict Horus Heresy
Date 0014.M31
Location Terra
Outcome Pyrrhic Loyalist victory
Imperial Eagle.jpgImperium of Man Chaos.pngForces of Chaos
Imperial Eagle.jpgEmperor of Mankind (WIA)

HighLordsSymbol.jpgImperial Regent Malcador the Sigillite (KIA)
Impfistslogo.pngPrimarch Rogal Dorn
Bloodangelslogo.pngPrimarch Sanguinius (KIA)
White Scars Symbol.pngPrimarch Jaghatai Khan (WIA)
SalamandersSymbol.jpgPrimarch Vulkan (Hidden)[14]
Custodesflag.JPGCaptain-General Constantin Valdor
Impfistslogo.pngFirst Captain Sigismund
Impfistslogo.pngCaptain Archamus[13d]
Impfistslogo.pngCaptain Fafnir Rann[10j]
Impfistslogo.pngCaptain Camba Diaz (KIA)[13e]
Impfistslogo.pngCaptain Maximus Thane[8]
Impfistslogo.pngCaptain Fisk Halen[13a]
Impfistslogo.pngCaptain Diamantis
Bloodangelslogo.pngFirst Captain Raldoron
Bloodangelslogo.pngGuard Commander Azkaellon
Bloodangelslogo.pngCaptain Nassir Amit
Bloodangelslogo.pngDominion Zephon
Bloodangelslogo.pngCaptain Bel Sepatus (KIA)
Bloodangelslogo.pngExarch Anzarael
Bloodangelslogo.pngCaptain Khoradal Furio
Bloodangelslogo.pngCaptain Idamas (KIA)
Bloodangelslogo.pngCaptain Satel Aimery
Bloodangelslogo.pngChampion Emhon Lux (WIA)
White Scars Symbol.png Lord Commander Qin Fai Noyan-Khan(KIA)[13]
White Scars Symbol.png Lord Commander Ganzorig Noyan-Khan
White Scars Symbol.png Captain Shiban Khan[13g]
White Scars Symbol.png Captain Jangsai Khan[13g]
White Scars Symbol.png Chief Stormseer Naranbaatar (KIA)[13d]
White Scars Symbol.png Captain Namahi
Impfistslogo.pngLt. Commander Sevastin Haeger[10j]
DAHeresySymbol.jpgCaptain-Paladin Corswain[13g]
SWHeresySymbol.jpgRune Priest Bodvar Bjarki[14]
SalamandersSymbol.jpgAtok Abidemi[14]
SalamandersSymbol.jpgIgen Gargo[14]
SalamandersSymbol.jpgBarek Zytos (KIA)[14]
Custodesflag.JPGShield Captain Amon Tauromachian[10j]
Custodesflag.JPGPrefect Warden Tsutomu (KIA)
Mechanicussymbol.jpg Fabricator-General Zagreus Kane
Collegia-Titanica-Symbol.jpgPrinceps Maximus Cydon (KIA)
Collegia-Titanica-Symbol.jpgPrinceps Esha Ani Mohana[9m]
Collegia-Titanica-Symbol.jpgPrefect Aurum
Imperial Army Symbol.jpgLord Commander Militant Adreen
Imperial Army Symbol.jpgHigh Primary Solar General Saul Niborran (KIA)[13]
Imperial Army Symbol.jpgMilitant General Konas Burr (KAI)[13]
Imperial Army Symbol.jpgMunitorum General Ilya Ravallion
Imperial Army Symbol.jpgMistress Tacticae Katarin Elg (KIA)
Imperial Army Symbol.jpgMistress Tacticae Sandrine Icaro
Imperial Army Symbol.jpgMarshal Aldana Agathe (KIA)[13]
Imperial Army Symbol.jpgGeneral Yennu Egwu[10j] (defects)
Imperial Army Symbol.jpgGeneral Nasuba
Imperial Army Symbol.jpgMilitant Colonel Clement Brohn
Custodesflag.JPGTribune Diocletian Coros
SoSSymbol.jpgKnight-Commander Jenetia Krole (KIA)[13g]
Luna Wolves Legionssymbol.jpgCaptain Garviel Loken[13f]
Captain Nathaniel Garro (KIA) [13f]

SoHSymbol.jpgWarmaster Horus Lupercal (KIA)

IWPreHeresySymbol.jpgPrimarch Perturabo (AWOL)
WEPad.jpegPrimarch Angron (Banished)
ThousandSonsPad.jpgPrimarch Magnus the Red (Banished)
EC Symbol.jpgPrimarch Fulgrim (AWOL)
DGSymbolNew.jpgPrimarch Mortarion (Banished)
Mechanicussymbol.jpgFabricator-General Kelbor-Hal
SoHSymbol.jpgFirst Captain Ezekyle Abaddon
SoHSymbol.jpgCaptain Horus Aximand (KIA)[13f]
SoHSymbol.jpgCaptain Falkus Kibre (KIA?)[13f]
SoHSymbol.jpgTormageddon (KIA)[13f]
SoHSymbol.jpgCaptain Tybalt Marr (KIA)[13f]
SoHSymbol.jpgCaptain Lev Goshen (MIA)[13f]
SoHSymbol.jpgCaptain Azelas Baraxa
SoHSymbol.jpgCaptain Indras Archeta (KIA)
SoHSymbol.jpgCaptain Xhofar Beruddin
SoHSymbol.jpgCaptain Lycas Fyton(KIA)
SoHSymbol.jpgCaptain Malabreux
SoHSymbol.jpgCaptain Hellas Sycar
SoHSymbol.jpgCaptain Taras Balt
SoHSymbol.jpgCaptain Vorus Ikari
SoHSymbol.jpgCaptain Selgar Dorgaddon
SoHSymbol.jpgCaptain Kalintus
SoHSymbol.jpgCaptain Zistrion
SoHSymbol.jpgEkron Fal
WBSymbolNew.jpgDark Apostle Erebus
WBSymbolNew.jpgDark Apostle Zardu Layak (KIA)[10j]
WBSymbolNew.jpgChaplain Inzar Taerus (KIA)
DGSymbolNew.jpgFirst Captain Typhus
DGSymbolNew.jpgCaptain Caipha Morarg
DGSymbolNew.jpgMarshal Gremus Kalgaro (KIA)
DGSymbolNew.jpgApothecary Zadal Crosius
WEPad.jpegCaptain Khârn (KIA)
WEPad.jpegCaptain Shâhka[23]
ThousandSonsPad.jpg First Captain/Chief Librarian Ahzek Ahriman
ThousandSonsPad.jpg Magister Amon
ThousandSonsPad.jpg Master Ignis
IWPreHeresySymbol.jpgWarsmith Forrix (AWOL)[10j]
IWPreHeresySymbol.jpgWarsmith Kroeger (AWOL)[10j]
IWPreHeresySymbol.jpgWarsmith Barban Falk (AWOL)[10j]
IWPreHeresySymbol.jpgWarsmith Ormon Gundar (KIA)[13f]
IWPreHeresySymbol.jpgWarsmith Bogdan Mortel (KIA)[13f]
NightLordsPad2.jpg Lord Commander Gendor Skraivok (MIA)
NightLordsPad2.jpg Krostovok
EC Symbol.jpgLord Commander Eidolon (AWOL)
EC Symbol.jpgChief Apothecary Fabius (AWOL)
Khorne mark.pngBloodthirster Ka'Bandha (Banished)
Nurgle mark.pngDaemon Prince Cor'bax Utterblight
Chaos.pngDaemon Prince Vassukella
Mechanicussymbol.jpgMagos Sota-Nul
Mechanicussymbol.jpgMagos Ardim Protos[9m]
Mechanicussymbol.jpgMagos Axmar Tre[9m]
Mechanicussymbol.jpgMagos Clain Pent[9m]
Mechanicussymbol.jpgMagos Illivia Epta[9m]
Mechanicussymbol.jpgArchmagos Inar Satarael[10j]

Impfistslogo.pngImperial Fists
Bloodangelslogo.pngBlood Angels
White Scars Symbol.pngWhite Scars
DAHeresySymbol.jpgDark Angels contingent
Imperial Army Symbol.jpgImperial Army
Mechanicussymbol.jpgAdeptus Mechanicus
Custodesflag.JPGCustodian Guard
SoSSymbol.jpgSisters of Silence
See Order of Battle for full
SoHSymbol.jpgSons of Horus
IWPreHeresySymbol.jpgIron Warriors

WEPad.jpegWorld Eaters
ThousandSonsPad.jpgThousand Sons
EC Symbol.jpgEmperor's Children
DGSymbolNew.jpgDeath Guard
WBSymbolNew.jpgWord Bearers elements
NightLordsPad2.jpgNight Lords elements
Mechanicussymbol.jpgDark Mechanicum
Traitor Imperial Army
The Lost and the Damned
See Order of Battle for full

Massive both military and civilian
Sanguinius killed
Emperor interred on Golden Throne
Horus killed
Mortarion, Angron, and Magnus banished

The Siege of Terra was the penultimate battle of the Horus Heresy. Waged on Terra, the homeworld of humanity, the massive engagement between the forces of the Imperium of Man and the forces of Chaos decided not only the fate of Horus Heresy but also that of humanity.



Following the Drop Site Massacre, the traitorous Warmaster of the Imperium and Primarch of the Sons of Horus, Horus, had crippled three Loyalist Space Marine Legions, a Loyalist Primarch, Ferrus Manus, had fallen in battle, another (Leman Russ) was severely wounded and a third (Vulkan) was thought missing in action. The Raven Guard, Salamanders, and Iron Hands had been badly mauled in the massacre. Only the Imperial Fists, Blood Angels, and White Scars Space Marine Legions were in the Sol System in force. The Ultramarines, Space Wolves, and Dark Angels were either too far away or bogged down in their own campaigns to come for aid.[1a]

Facing them were the armies of Chaos under Warmaster Horus which included nine Legions of Chaos Space Marines, traitorous forces of the Imperial Army, Daemonic hordes, and the Titan Legions of the Dark Mechanicum.[1a] Mars, the capital of the Adeptus Mechanicus, had recently fallen to the traitor forces. The situation had become disastrous for the Imperium and the forces of the Emperor. Horus, sensing that he could decisively end the conflict and overthrow the Emperor once and for all, began to move on Terra. Rogal Dorn, Primarch of the Imperial Fists, was given overall command of the defenses of humanity's homeworld while the Emperor himself was busy with his own secret project, the Golden Throne.[1a] In addition to the loyalist Space Marine forces deployed in the Sol System, the loyalists were bolstered by the Custodian Guard, Sisters of Silence, millions of Imperial Army troops as well as various Mechanicum forces such as Titan Legions, Knights, Legio Cybernetica, and Skitarii. Much of Terra's population was forcibly conscripted in the stages before the battle, with millions of terrified Conscripts being handed a Lasgun with virtually no training. Most of these were deployed in the 3-layered trench network around the Walls of the Imperial Palace, with Dorn intending to save his Astartes and Mechanicum troops for the later stages of the battle.[9a]

Following the Battle of Beta-Garmon, the door to the Sol System was open and Horus finally mustered his forces on Ullanor after years of war. They included the Sons of Horus, World Eaters, Emperor's Children, Thousand Sons, Death Guard, and Iron Warriors under their respective Primarch's. These were bolstered by disparate forces of Night Lords under Captain Gendor Skraivok and 5,000 Word Bearers under Dark Apostle Zardu Layak. The Alpha Legion left the Solar warzone after delivering a detailed map of the Sol System's defenses to Horus.[4] During the final phase of the Solar War, Horus' forces captured the Sol System from the loyalists. All that now lay his path to victory was Terra itself.[7] Horus intended to capture Terra before the arrival of Roboute Guilliman from the galactic east, though he deployed Perturabo and the Iron Warriors to fortify the captured Sol System against any who may intrude upon the siege.[9a]

The Storm Breaks

The siege of the Imperial Palace.

On the thirteenth day of Secundus, the bombardment of Terra began. From orbit, Horus' ships laid down an unrelenting barrage of missiles and energy beams. The first shell targeted the Sanctum Imperialis, the Emperor's personal quarters, for symbolic reasons, though it did no damage and was quickly intercepted by many point defense systems. A vicious exchange of fire took place as the massive array of anti-ship gun batteries on Terra opened up on the traitor ships. Losses were incurred by both sides, but the traitor fleet in particular took heavy losses in space but endured through sheer weight of numbers.[9a] Horus' ultimate objective was the Imperial Palace, seat of the Emperor himself. The orbital bombardment was some of the most intense ever witnessed and shook even the courageous and battle-hardened loyalists Space Marines.[1b] However damage to the actual Palace itself was minimal due to a sophisticated multi-layered and self-repairing Void Shield system known as The Aegis as well as the fact that Terra's last orbital plate was placed over the Palace to serve as a shield and gun platform. However, due to a reactor flaw in one of the Aegis' reactors, a small weakness appeared in the Palace network centered around a Bastion outside the Helios Gate.[9a] Inside the depths of the Palace itself, the Emperor, attempting to keep the Golden Throne under control, could only brood over the desperate events occurring far above.[1b]

The bombardment continued for days as Perturabo probed for weaknesses in the Aegis, discovering the flaw around Bastion-16. The Aegis around this area was weakened enough to allow for slow-moving aircraft to penetrate. Despite the ragings of Angron and the boredom of Fulgrim, Horus would not launch an all-out attack yet. The Emperor's might not only prevented Daemons from manifesting on Terra, but also threatened to destroy the Daemon Primarch's should they set foot upon its soil. Magnus and Zardu Layak surmised a ritual to eliminate the Emperor's barrier by spilling enough blood across Terra. Horus began to increasingly spend his time comatose, his spirit inside the Warp searching for lore as well as weakening the Emperor's spirit,[9b] eventually designating First Captain Ezekyle Abaddon as his proxy.[9d]After 12 days the bombardments continued, but were matched with the first ground assaults. Thousands of traitor vessels crashed into Terra's surface. Many were destroyed by the Palace defenses, but many more landed and unleashed endless hordes of Traitor Imperial Army, Beastmen, Cultists, and Mutants. These were largely distractionary measures to support the traitors' true objectives as they ravaged the planet, as well as support the traitor aerial attacks on the Palace's anti-ship guns and void shield generators. The loyalists responded with their own aerial defenses, and massive dogfights erupted over the Palace as the conscripts outermost trenches around the walls held against the attacks by the Lost and the Damned. While the Palace held, elsewhere across Terra major population centers fell such as Lundun, Noy Zaylant Hive, Neork, and Braslya.[9l]

The Dark Mechanicum siege camps around the Imperial Palace

The pattern of orbital attack, landings by traitor rabble, and aerial assault repeated itself for weeks before the Death Guard fleet under the now-corrupted Mortarion arrived at Terra. True to his earlier word to let Mortarion's legion be the first to set foot upon Terra, Horus prepared to use the Death Guard in the first Astartes-led assaults on the Palace.[9d] This caused Angron to rage, and to prevent him from destroying his own flagship The Conqueror he was teleported by World Eaters 8th Company Captain Kharn into the ever-shifting labyrinth originally built for Vulkan aboard the Night Lords flagship Nightfall.[9f] On the seventh of Quartus the first Death Guard Drop Pods landed on Terra's soil as the Nine Disciples of Kelbor-Hal each beached one of their Ark Mechanicus-class Battleships around the Palace. The Void Shields and bulk of the Ark Mechanicus vessels allowed for the traitors to establish their first real footholds around the Palace, and as the Death Guard unleashed gas and plagues upon the trenches around the walls the Dark Mechanicum set about their work of constructing siege engines.[9e] The Death Guard assault on the outermost trenches around the Palace was about to break the Imperial Army defenders until Jaghatai Khan, defying Dorn's orders to remain in the palace, led a Jetbike charge by the White Scars. The Scars pushed past the traitor frontline into their siege camps before the Khan was finally forced from his Jetbike. Jaghatai slew dozens of Death Guard until he was wounded by a Warp-tainted poisoned blade. Ultimately Sanguinius had to sortie out of the Palace with his Sanguinary Guard to rescue Jaghatai, who recovered from his Warp sickness as soon as he began to move closer to the Sanctum Imperialis and the psychic might of the Emperor. The Khan's move was not reckless however, he also gathered valuable intelligence on the siege engines the traitors were constructing.[9g] Meanwhile aboard the Vengeful Spirit, Horus finally allowed Perturabo to begin his preparations to clear landing zones around the Palace for their Titans.[9h]

On the Fifteenth of Quartus, the traitors initiated their dual plan to break The Aegis and allow for the manifestation of Daemons upon Terra. A giant projected face of Zardu Layak appeared on an island of bones which descended from the sky, urging the commoners of Terra to rise up against the Emperor and ensuring them that if they turned to Horus now they would be spared. The Palace guns could not silence the corporeal island, and after his speech concluded it began to rain blood. The blood signaled that the traitors had finally undertaken their ritual to weaken the Emperor's psychic barrier, and the Mechanicum released their Daemon Engines. Eight "Warp-Bane" guns constructed near the sites of the beached Ark Mechanicus vessels opened up on the Aegis Shield around the Palace, sapping it of its energies as the Death Guard deployed massive Towers of Nurgle at the walls. As the Aegis gave way the traitor bombardment finally was able to hit the Palace defenses directly, causing massive devastation and allowing for a Night Lords Raptor assault on the Eternity Wall. The outermost trenches around the Palace Walls were now untenable, but Sanguinius opened up the Helios Gate and led a massive counterattack by the Blood Angels and Imperial Fists as well as Titans of the Legio Solaria. Sanguinius knew victory was impossible, but had his Astartes buy enough time to allow for the Imperial Army conscripts to make it inside the walls and allow for Titans to destroy the incoming Towers of Nurgle.[9i] On top of the Eternity Wall itself, Blood Angels First Captain Raldoron bested the acting Night Lords commander Gendor Skraivok and threw him from the Walls.[9j] It was in this maelstrom of destruction that Angron himself fell from the sky, having been released from the bowels of the Nightfall. After massacring his way through friend and foe alike to the Eternity Wall Angron bellowed a challenge to Sanguinius, who saluted his fallen brother and stated that while they would battle one day, today was not that day. Angron raged, but could not proceed any further due to the lingering effects of the Emperor.[9k]

The Imperial Palace under siege[2]

Battle for Lion's Gate Spaceport

Though the rest of Terra was in chaos or in Traitor hands, the Palace stood firm. All traitor attacks against the walls failed to achieve a breakthrough, and the Emperor's psychic shield endured strong enough to keep the Daemon Primarch's from the Palace. In order to further the weakened Emperor's barrier, both Horus and Magnus launched psychic attacks against Him. Magnus utilized the gestalt Daemon Shai-Tan in the attacks.[11] At Horus' command Mortarion attacked near the Saturnine Gate turning the previously lavish Palatine Arc into an infected quagmire nicknamed Poxville. Angron fruitlessly rampaged outside of the Helios Gate, and Fulgrim's degenerate hordes launched raids to both the west and north. The Emperor's Children were already beginning to leave the frontline, instead taking prisoners for their own perverse reasons. Of Magnus there was no sign, and not even Malcador could ascertain his true intentions. In this stalemate, Horus placed Perturabo in charge of achieving a major breakthrough. Perturabo surmised that the Lion's Gate Spaceport was both the weakest and strongest points in the Palace's defenses. Taking it would allow the traitors to land badly needed Titans and give the traitors access to both the Inner and Outer Palaces. At the same time however, it was one of the most heavily defended bastions. This did not deter Perturabo, and he shocked his First Captain Forrix by placing Warsmith Kroeger in charge of the assault on the Spaceport. Perturabo hoped that Koreger's bluntness would shock Dorn, who had planned for a more sophisticated attack.[10a]

The Imperial Forces at the Lion's Gate Spaceport numbered 18,000 Imperial Fists and nearly 800,000 Imperial Army troops under the command of Fafnir Rann. To break this, the traitors amassed a massive force of their own. 25,000 Iron Warriors, thousands more World Eaters under Kharn, 2,308 Basilisks, 1,500 Manticores, 13 Bombards, 476 Deathstrike Missile Launchers, 495 Medusas, 84 Typhon Heavy Siege Tanks, 7,108 Thunderburst towed guns, 306 Siege Dreadnoughts, and tens of thousands of Astartes tanks representing 80% of the Iron Warriors Legion's Armor. Supporting this were 1.5 million traitor Imperial Army troops and untold numbers of Beastmen, Mutants, and Cultists.[10b]

Despite the apprehensions of Forrix, Kroeger chose not to launch a massive preliminary bombardment and instead launched an immediate attack on the Walls outside the Lion's Gate Spaceport. To the surprise of the traitors the Fists under Fafnir Rann forayed out of the Spaceport and formed a Shield Wall, pressing the Lost and the Damned masses together as Astarted armor moved around on their flanks. The armored encirclement decimated the traitors, wiping out 300,000 troops in under two hours. The traitor attack stalled until the appearance of Angron himself, who managed to turn the tide. However as the Emperor's psychic shield prevented the Daemon Primarch from moving into the Palace Walls, the traitors failed to take the Spaceport.[10c] Following the failed attack, Perturabo realized that to take the Walls they must combat the immaterial might of the Emperor, Horus agreed, and gave Perturabo the support of Zardu Layak and Abaddon as well as Typhon. The four moved back down to the Palace Perimeter and enacted a ritual that would summon Cor’bax Utterblight into the minds of the mortal defenders of the Palace, forcing the Emperor's psyche to its limits.[10d] Meanwhile at the orders of Kroeger Forrix and 1,000 Iron Warriors infiltrated into the Spaceport, using the earlier attack as a smokescreen to move in and seize the bridges between the Spaceport and Lion's Gate itself. However in truth Kroeger intended to abandon Forrix behind enemy lines, or at the very least simply didn't care enough to lend him support. Shortly after Forrix's infiltration, 3,000 Sons of Horus under Abaddon alongside forces from the World Eaters under Kharn and Iron Warriors under Kroeger and Berossus attacked the upper tiers of the Spaceport.[10e]

Dorn agreed to provide Rann with reinforcements under Sigismund to prevent a total traitor victory at the Spaceport. During the defense Rann was wounded by Kroeger but saved by Sigismund, who led a vicious counterattack.[10f] It soon became apparent that the Iron Warriors attempt to seize the bridges had been simply a feint. Perturabo used Forrix's men to shield his true intentions, docking the Iron Blood with the Space Port's space elevator facilities and unloading waves of new reinforcements. The defection of the Addaba Free Corps prevented Dorn from sending reinforcements and the situation collapsed for the loyalists. In the ensuing brawl Sigismund battled Kharn, but while the First Captain was the superior warrior the World Eater's Captain was now infused with Khornate strength. Sigismund was bested, but saved by the appearance of Rogal Dorn himself who slapped away Kharn like an insect. Abaddon refused to allow Kharn to die and led a counterattack to save the World Eater, forcing Layak to intervene in order to save the future Warmaster of Chaos from the Primarch's wrath.[10g] Layak held off Dorn for a time with his sorcerous power, but was eventually slain. However, as he died he opened a portal to the Warp which allowed the first Daemon's to manifest on Terra. With the situation now hopeless, Dorn ordered a withdrawal as Perturabo himself landed in the Spaceport. The two brothers came face to face, but both refused to waste their time and resources engaging one another in a fruitless duel. Perturabo had taken the First Wall, but there were still many more left to capture before the Sanctum Imperialis. Perturabo was undeterred as he oversaw the landing of the first Traitor Titans from the Legio Fureans upon Terra.[10h]

Meanwhile inside the Inner Palace, Euphrati Keeler's Lectitio Divinitatus continued to gain influence in the throngs of refugees and desperate. However, their faith was a deception by Chaos, which allowed Utterblight to manifest inside the Sanctum Imperialis itself. Thanks to the efforts of Malcador, Sisters of Silence, and Amon Tauromachian total disaster was averted, but the incident combined with the constant immaterial assaults by Horus and Magnus forced the Emperor's psychic shield to reduce to only around the Sanctum Imperialis. With the Emperor weakened, massive amounts of Daemons were summoned on Terra for the first time. Meanwhile, Angron led a horde of World Eaters towards the Eternity Wall. Dorn was not shocked by the fall of the Spaceport, and in fact, was satisfied that he had held it longer than he thought he would. All that mattered to the Primarch was to buy enough time for Guilliman to arrive.[10i]

Defense of the Lion's Gate

With Horus still isolating himself aboard the Vengeful Spirit, Perturabo became the general commander of the traitor war effort, maintaining a war council alongside the Mournival, Eidolon, Typhus, Ahriman, and Krostovok. On the 19th day of Quintus, the Traitors unleashed a massive assault with weapons of mass destruction and other high-yield weaponry which utterly annihilated the Magnifican, the northeastern half of the Palace megastructure. The operation was overseen by three Iron Warriors Stor-Bezashk. In the wake of the mass explosions Gastraphetes, Gravitic Ballistas, Manuballistas, Torsion Engines, Graviton Onagers, Trebuchets, and Accelerator Mangonels unleashed a bombardment against the next line of Loyalist defenses. They fired ouslite, chemical, incendiary or tungsten ordnance while others simply recycled the destroyed masonry of the Magnifican, hurling it back at the defenders. The enormous explosions and impacts created a cloud of ash that caused perpetual night on Terra. Though the Magnifican had already largely fallen to the traitors, Perturabo destroyed this section in order to prevent remaining loyalists from using the massive urban sprawl as cover for delaying actions.[13a]

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]

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 organized 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 dissapating 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 Ruinious 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] 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]

Despite this setback, Horus remained undeterred. He organized a massive attack by the Legio Mortis, Sons of Horus, Chaos Knights, and Dark Mechanicum war engines against the Mercury-Exultant Kill-zone, a 150km-deep No Man's Land before the Exultant Wall which connects the Inner and Outer Palaces. This massive force was met by some 50 engines of the Legio Ignatum[15a], including the Emperor Titans Imperious Prima, Exemplis, and Magnificum Incendius. This formidable army was aided by not only the shattered remains of other Titan Legions such as the Legio Solaria, Legio Atarus, Legio Defensor, Legio Amaranth, Legio Gryphonicus, and Legio Invigilata but also dozens of Knight Houses and supporting Imperial Army and Secutarii.[15b] The Ordo Sinister also finally agreed to enter the fighting, sending a Warlord-Sinister Psi-Titan to the Ignatum's aid.[15d] In the ensuing apocalyptic battle, the Traitors first attacked with waves of destroyed Titans that had been resurrected through sorcery. These "zombie" Titans now walked without a living Princeps, and were largely used as cannon fodder by the Traitors due to their ability to absorb enormous amounts of punishment.[15c] In their wake came the Legio Mortis and endless swarms of Dark Mechanicum vehicles and Daemon Engines. They were led by the Dies Irae and its bodyguard of 7 Warlord Titans.[15b] Despite the devastation wrought upon by the Traitors, thanks to orbital bombardment, new Warmaster Titans, weight of numbers, and madness spread amongst the loyalist mortal crews, the Traitors ultimately prevailed in annihilating the Legio Ignatum and its allies and reaching the Exultant Wall.[15e]

Jaghatai Khan confronts Mortarion at the Lion's Gate Spaceport[20g]

Horus ordered his army to push on and had the attack on the outer walls of the Imperial Palace be spearheaded by the Death's Head Titan Legion. Losing five Titans within minutes to entrenched loyalist defenses, the traitor forces would not relent and kept hammering away at the palace walls. A counterattack against the Chaos horde's flanks by loyalist titans failed, though the White Scars took advantage of the confusion it caused to sweep down at the traitor forces rear columns and wreak havoc.[2] The Siege of the Imperial Palace soon ground on for many days, with the two primary attacks during this time being made by Angron and his World Eaters supported by Daemon Engines in one sector and the Legio Mortis in the other.[1c] Under a the vicious combined attack by the World Eaters and Legio Mortis, major breaches were made at the Mercury and Exultant Wall zones. The way to the Sanctum Imperialis was now clear and the loyalist defenders seemed doomed, with many seeing the battle now as a suicidal final stand rather than one in which they could emerge victorious.[20a]

Battle for the Astronomican

Meanwhile, the force of Dark Angels under Corswain remained in the fringes of the Sol System, rendezvousing with Admiral Niora Su-Kassen and her hidden fleet led by the Phalanx. It was agreed that the Dark Angels should make for Terra to aid the defenders, but they would need something significant in order to break the traitor blockade of the world. Su-Kassen provided the enormous Battle-Carrier Imperator Somnium, the former flagship of the Emperor himself. The ship was largely evacuated of crew and sent plummeting towards the traitor fleet as the Dark Angels vessels hid in its wake. Though torn apart by enemy fire, the mighty Imperator Somnium was able to destroy four World Eaters Heavy Cruisers and an Emperor's Children Battle Barge. Afterwards, the explosion of the Emperor's ship heavily damaged the Terminus Est and the Conqueror battleships.[15f]

The Dark Angels vessels were able to launch a Drop Pod landing operation to deliver their warriors to Terra, with Corswain's force landing upon the Hollow Mountain. Battling through the Emperor's Children and many warp-spawned horrors inside the Fortress including the Daemon Vassukella, Corswain was able to establish contact with Dorn and announced his intent to attempt and reactivate the Astronomican.[15g] Subsequently, Corswain and his Dark Angels found themselves besieged by traitor forces and struggling to hold the Astronomican.[22b]

Retaking the Lion's Gate Spaceport

This grim outlook was not shared by the White Scars and their Primarch, Jaghatai Khan, who continued to talk of life after they had won the battle.[20a] Not content to simply hide behind walls, the Khan at last decided at this desperate final hour to make his move. He became committed to retaking the Lion's Gate Spaceport, which if captured would allow Guilliman's coming reinforcements to quickly land on Terra as well as slow the flow of traitor forces. Overworked and exhausted and knowing he could not control his brother, Rogal Dorn did not try to stop the Khan. Facing the White Scars were the bulk of the Death Guard under Mortarion, who had taken up Lion's Gate Spaceort as his new headquarters since the departure of Perturabo.[20b]

For the operation to recapture Lion's Gate, the Khan mustered not only nearly the entire White Scars Legion but also the Terran First Armored and the Sky Fortress, the last Orbital Plate on Terra that until now was being used as an airborne carrier and fire support platform. After much careful planning, the Khan struck with an overwhelming push by thousands of Imperial Army tanks protected by White Scars infantry. In their wake came a massive charge of White Scars Jetbikes. Gold Battlefront under Ganzorig Noyan-Khan struck an arrowhead across the northern sections of the space port approaches, while Ebony under Qin Fai Noyan-Khan attacked the southern flank. Jaghatai Khan himself led Amber Battlefront through the center and directly into the thickest enemy defenses.[20c] The ensuing fighting was ferocious, even for the standards of the Siege. The Sky Fortress was able to fulfill its mission to provide fire and aerial support for the White Scars until it was shot down, crashing into the Imperial Fleet College and creating a massive explosion. While the White Scars and Imperial Army tanks were able to quickly push to the Lion's Gate Spaceport, inside their advance began to become bogged down by the stubborn defenses of not only the Death Guard, but also their Daemonic and Mutant allies. A war of attrition broke out, one in which the White Scars were ill-suited but the Death Guard excelled at.[20d]

As loyalist casualties mounted, the Khan was able to fight his way into the heart of the Spaceport and confront Mortarion himself. The old enemies exchanged few words before engaging in a final duel. Faced with Mortarion's new Daemonic endurance and strength, the Khan was brutally beaten down and nearly defenseless. However he was able to find a weakness in the Death Lord with his pride. Jaghatai Khan scolded Mortarion for being weak and giving into the powers of the Warp, while he himself had resisted the temptations of Chaos and remained true to the Emperor. Mortarion flew into a rage, which the Khan took advantage of to launch a second wave of dizzying attacks that overwhelmed the Primarch. In the end the badly wounded Jaghatai Khan was impaled on the blade of Mortarion's scythe, but simply pulled his body along its length to get face-to-face with the Death Guard Primarch. The loyalist Primarch decapitated Mortarion, who was banished into the Warp in a massive explosion similar to that of a Vortex Weapon. Later, the Khan's badly wounded body was discovered by Ilya Ravallion and Jangsai Khan.[20e]

In the aftermath of the Khan's seeming death, the White Scars were thrown into a frenzy and prepared to throw their lives away in a final charge against the Death Guard. The sudden tenacity surprised the Death Guard, who without Mortarion to guide them were forced back. Thanks to the efforts of Ilya Ravallion and Shiban Khan the White Scars decided to remain at Lion's Gate Spaceport and secure it for the loyalists instead of pressing on into certain death.[20e] Meanwhile, the surviving Death Guard rallied under Typhus, who had stationed himself just outside the battlezone.[20f]

The Adeptus Custodes battle Daemons at the Imperial Palace
Sanguinius' stand at the Eternity Gate[21]

Last Stand at the Eternity Gate

Despite the retaking of the Lion's Gate Spaceport, the situation continued to degrade for the loyalists and nothing could stop the tide of traitors pouring into the Inner Palace from the parts of the Ultimate Wall broken open by the Legio Mortis. Even the Bhab Bastion, Dorn's command center, became besieged with the Imperial Fists Primarch still inside. By this point the traitor armies have lost much of their cohesion, turning into a barbaric horde that swept forward murdering all in its path. The Emperor's psychic shield was near-breaking point thanks to a constant immaterial assault by the debased form of Magnus in the Webway. To try and stop the Crimson King, Vulkan was dispatched into the Webway to find and kill Magnus before he could succeed. As whoever could fled towards the Sanctum Imperialis Horus himself appeared over the traitor communicatons network for the first time in weeks to give a single order to his forces: the capture of the Eternity Gate at dawn.[22b][22c]

As a vast taritor horde of traitor Astartes, Imperial Army, Beastmen, Mutants, Daemons, Titans, and other horrors massed on the horizon, only some 70,000 defenders mustered on the Delphic Battlement before the processional to the Eternity Gate. These were mainly Blood Angels and Imperial Army, but Imperial Fists, White Scars, Legio Ignatum, and Mechanicum loyalists were also represented. Corswain offered to send his own forces defending the Astronomican to aid the defenders, but Sanguinius refused them to the vital nature of the Dark Angels Paladins mission.[22a]

Faced with certain death before the vast traitor horde, Sanguinius nonetheless organized a defense to try and buy precious time. At dawn the traitors erected the mutilated but still-living loyalist prisoners they had nailed to banners, crosses, vehicles, or whatever else they could find to try and break the spirit of the defenders. Next marched forth the Daughter of Torment, a Reaver Titan of the traitorous Legio Mordaxis. In its Power Claw was the tortured form of Blood Angels Captain Idamas. It issued forth Horus' conditions, that any who fled the coming battle would be granted a pardon by Horus, new Emperor of mankind. Sanguinisu responded with a rousing speech to the defenders, stating that he would stand and fight but all others were free to go where they wished. Inspired or perhaps shamed by the Great Angel, it is believed that no loyalists took the opportunity to leave and instead all present pledged themselves to Sanguinius. The Blood Angels Primarch next took to the skies and behead the Daughter of Torment as battle erupted.[22d]

The battle that followed was immense. The traitor horde surged forward as the guns of the Delphic Battlements opened up. The initial waves were decimated, but through weight of numbers they began to reach the walls. A Khornate Warlord Titan docked with the Delphic wall, vomiting forward World Eaters from its mutated mouth. Chaos erupted in short order as the battle turned into a savage melee. Into this strode the Bloodthirster Ka'Bandha, who had been bested by Sanguinius during the Signus Campaign. Vowing to reap 500 Blood Angels in the presence of their Primarch, the Daemon nearly succeeded before Sanguinius intervened. The two had a dramatic airborne battle that ended when Sanguinius broke the Daemons back with the hilt of his sword. Ka'Bandha plummeted to the earth, consumed by lesser Daemons taking advantage of his weakness.[22e]

With the traitor horde still advancing and Daemons now manifesting even inside the Sanctum Imperialis itself Custodian Tribune Diocletian Coros ordered the Eternity Gate shut. However it was then that Legio Audax Titans intervened, using their Ursus Claws to force one of the doors open. Sanguinius was about to cut these chains when Angron surged from the sky, directed by Horus himself to kill his brother. Already weakened by his fight with Ka'Bandha, Sanguinius fought a desperate battle against Angron but managed to initially hold his own. After a climatic airborne battle, Angron impaled Sanguinius upon his Black Blade. However Sanguinius used the opportunity to rip out Angron's Butchers Nails, causing the Daemon Primarch's head to explode. With Angron banished into the Warp, the World Eaters lost whatever sanity they had and began to cut down their own allies. This combined with the defeat of Magnus in the Webway at the hands of Vulkan broke the traitor advance just short of the Eternity Gate, which managed to finally seal shut as the surviving loyalists fled inside.[22e][22f]

Just moments after the battle of the Eternity Gate, Shiban Khan and his White Scars managed to reactivate the anti-orbital defenses of the Lion's Gate Spaceport. The traitor armada, hanging in low-orbit, was subjected to a vicious ground-to-orbit bombardment. Word reached the Sol System that Roboute Guilliman was just one week away, with Leman Russ, Corax, and Lion El'Jonson not far behind.[22f]

Despite the victory at the Eternity Gate, the situation for the loyalists was still dire and Chaos forces were advancing all fronts. Remaining loyalist officers such as Fafnir Rann, Zephon, Nassir Amit, Maximus Thane, and Namahi led desperate but futile defenses of the last battlements inside the Inner Palace. While nearly all order and discipline had by now broken down amongst the Traitor Astartes, vast Daemonic legions spilled forth as legendary figures such as Be'lakor, Skarbrand, Ulkair, N'Kari, Heartslayer, Drach'nyen, Epidemius, Ku'gath, Madail, Karanak, The Masque, Doombreed, Tallomin, and Skulltaker manifested on Terra's soil.[24a] Just hours after the shutting of the Eternity Gate, the Bhab Bastion itself was overrun by Sons of Horus forces under Tarchese Malabreux and Rogal Dorn was forced to retreat into the Sanctum Imperialis.[24b] Concepts such as time and space started to break down and mere hours passed as if it were weeks as Terra itself began to slowly be sucked into the Warp, with the Vengeful Spirit as its conduit.[24c] All across Terra, traitor armies and maddened souls began to chant the name of the "Dark King". Horus now aspires to become the fifth God of Chaos born from Humanity just as Slaanesh was born from the Eldar.[24d]

The Vengeful Spirit

It was at this moment that Horus finally emerged from Lupercal's Court for the first time since the Siege began, apparently in a half-lucid stupor and imagining himself back on the Great Crusade. Journeying to the bridge of the Vengeful Spirit, he addressed his equerry Kenor Argonis as Maloghurst, saw long-dead Zardu Layak at his side, and stated he would finally finish the war. To the shock of all present, Horus stated that he had apparently lowered the Vengeful Spirit's Void Shields, inviting the Emperor himself to Teleport aboard his flagship. This would allow Horus to slay the Emperor before reinforcements under Guilliman could arrive, which were mere hours away. With their Emperor dead, Guilliman's incoming fleet would lose heart and scatter before the forces of the Warmaster.[24e] However, Guilliman's fleet was still having difficulty finding Terra without the Astronomican, which Corswain and his Dark Angels sought to reactivate. To thwart the Dark Angels, Typhus led a massive Death Guard assault upon the Hollow Mountain.[24j]

Upon discovering the shields of the Vengeful Spirit down, Malcador the Sigillite alerted the Emperor, still struggling to keep the Golden Throne and its adjoining Webway Gate stable. Upon learning of the news, the Emperor knew it was time to act and end Horus, even though he was certain it was a trap. Rogal Dorn, Sanguinius, Vulkan, and Valdor were all called to his side for the coming battle, and all objected to the Emperor's plan to personally teleport aboard the Vengeful Spirit.[24f] However the Emperor overruled his sons, commanding Valdor and Dorn to come with him while Sanguinius took control of loyalist forces on Terra and Vulkan stay behind to oversee the potential failsafe on the Golden Throne.[24g] Sanguinius flatly objected to his fathers request to stay behind, telling the Emperor of his prophetic death at Horus' hands and his intention to defy fate by defeating his traitorous brother instead. This was enough to move the Emperor to change his mind. Four company's were organized for the assault: the Hetaeron Guard led by the Emperor, another Custodes company under Valdor, a mixed force of Sanguinary Guard and Blood Angels 1st Company under Sanguinius and Raldoron, and Huscarls under Dorn and Diamantis. The operation was codenamed Anabasis.[24h] Malcador took his place upon the Golden Throne in the Emperor's place, an act that would cost him his life. For that, The Emperor renamed Malcador the Sigillite to Malcador the Hero.[24i]

While the Emperor led the assault on the Vengeful Spirit, Archamus was placed in command of the reamining loyalist forces on Terra. Meanwhile a the Astronomican, Corswain and The Lord Cypher waged a battle against a Death Guard assault led by Typhus, who was attempting to stop the reactivation of the Astronomican. If the traitors succeeded, Guilliman's armada would have no way of reaching Terra in time.[24j] For the traitors part, upon discovering their flagships shields were down Abaddon abandoned the war on the surface along with the last few remaining sane Sons of Horus officers to rush to his fathers side.[24p]

Operation Anabasis

Upon teleporting to the Vengeful Spirit, Horus sprung his trap and had the attackers scattered through the ship as the Warmaster revealed he had deliberately held back the measure of his true strength and clouded his own mind in dementia in order to lure the Emperor in.[24o] The Emperor and his Custodes appeared in a seemingly ordinary hangar until Horus used his dark powers to take control of many of the Companions. Blood flowing from their eyes and screaming at the effort to maintain control, dozens of the Emperor's own bodyguards attacked their liegelord. The Emperor slew dozens of Custodes before the madness passed and He was able to cleanse the lingering taint from His companions. The Emperor and his Custodes then found themselves in the midst of Hell, with many of the warriors falling into Daemonic traps until the Emperor unleashed His psychic fire to cleanse it.[24k] Meanwhile, Valdor and his Custodes found themselves deep within a dark vault, battling hordes of Daemons and only realizing they were aboard the Vengeful Spirit when the Captain-General stabbed the surface with his Apollonian Spear to confirm their destination.[24l] Dorn found himself in an endless sweltering desert for what seemed to him to be centuries, slowly forgetting all but his name and being tempted by Khornate madness.[24m] Only Sanguinius and his Blood Angels reached their original destination, Disembarkation Deck 2, and it was here they faced determined resistance from Daemons, Sons of Horus, and Word Bearers.[24n]

The first to reach the traitorous Warmaster was Sanguinius himself. Refusing a final offer by Horus to join him in his campaign against the Emperor, the heroic Primarch found himself completely outmatched by the Warmaster, now warped by the powers of Chaos, and was struck down. When the Emperor finally reached Horus, he witnessed to his horror the mauled corpse of Sanguinius at the traitorous Warmaster's feet. Overwhelmed by sorrow, the Emperor was speechless as Horus mocked his once-beloved father, proclaiming himself the rightful ruler of humanity and claiming to have even bound the Chaos Gods to his will. The Emperor could only look on in pity, knowing all too well the trap that had ensnared his son. Stating that Horus had become a slave to Chaos, not the other way around, Horus became enraged and the great duel to decide the fate of humanity finally began.[1d]

Horus and The Emperor meet for their final battle

Though a Psyker of unparalleled might, even the Emperor found himself greatly challenged by the might of Horus and the Chaos energies that swelled within him as the two engaged in a titanic battle of not only Power Sword and Lightning Claw but also psychic power. However, even after all that he had done, the Emperor could not bring himself to use his full power and risk killing his beloved son. Using the immense power he had acquired during the Battle of Molech and imbued with the energies of all four Chaos Gods, Horus crushed the Emperor's windpipe, severed the tendons of his wrists, broke most of his ribs, plucked out his left eye, and set his hair alight. As if this weren't enough, Horus lifted the Emperor high above his head and brought him down upon his knee, crushing the Emperor's spine. Further punishing his father by ripping one of his arms from its sockets, Horus howled over the beaten body of the Emperor in triumph.[1d]

But suddenly, the beating stopped. A lone Custodian of the Adeptus Custodes had entered the room (while other sources state it was Ollanius Pius, an Imperial Army soldier). Without hesitation, the loyal warrior had charged towards Horus. Breaking out in laughter, the Warmaster blasted apart the warrior in a gaze of psychic energy. This proved to be the decisive moment in which the Emperor finally realized what his son had become. The Horus he had known was truly gone, destroyed by the maddening powers of Chaos. Realizing that he must kill Horus and he would never get another chance, the Emperor used the brief respite to lash out at Horus with his full power. Focusing his psychic bolt into a bolt of pure force, the lance of power blasted straight through the Warmasters heart. Realizing their pawn had failed, the Gods of Chaos retreated from Horus' body. As they did, sanity returned to the Warmaster. In that moment, Horus, realizing the atrocities he had committed, begged the Emperor to strike the finishing blow before the powers of Chaos would take hold over him once more. Focusing the last of his strength into another psychic bolt, the Emperor finally destroyed his repentant son.[1d]

Rogal Dorn and his Terminator escorts would reach the chamber shortly after, discovering the beaten body of the Emperor alongside the remains of Sanguinius and Horus. The Emperor only had enough strength to demand to be taken to the Golden Throne at once. Obeying his beloved master, Dorn and the surviving loyalist forces teleported off the Vengeful Spirit and back to the Imperial Palace. Meanwhile, the death of their Warmaster had sent a psychic shock reeling across the traitorous armies on Terra. As the Great powers of Chaos retreated from Horus they took their Daemonic hordes with them. Confusion broke out among the traitor Primarchs and the rebel armies lost all cohesion. It was said that the Sons of Horus, sensing their father's death, immediately broke and were the first to flee from the planet[5] while Mortarion and the Death Guard were the last.[6]

At the same time, the Blood Angels began suffering horrific visions of the death of Sanguinius. In what may be the first instance of the Black Rage, the Blood Angels broke ranks and began engaging the traitors in close combat with such savagery it shocked both loyalist and traitor Marine alike. Using this to their advantage, the loyalist forces led a decisive counterattack which finally expelled the traitorous legions from Terra in a bloody rout.[1d]


Though Horus had been slain and the traitorous forces were driven from Terra, tragedy was not yet over for the Imperium. Malcador had been reduced to a pile of dust from the strain of controlling the Golden Throne and the Astronomican in the Emperor's absence, and the dying Emperor himself was adamant that he himself be hooked back up to the arcane machine. Issuing his last spoken words to his most trusted followers which had gathered around him, the Emperor left the fate of humanity in the hands of his remaining Primarchs. Becoming silent, for the last ten thousand years he has remained interned on the Golden Throne, sustained by its advanced technology and the daily sacrifice of a thousand psykers.[1e]

The Horus Heresy did not end with the Battle of Terra. The Loyalists still had to drive the remaining rebels from the Imperium, one world at a time. In what became known as the Great Scouring, the traitorous forces of Chaos were eventually driven into the Eye of Terror.[1e]

Order of Battle




Conflicting sources

There are many differences with the narrative of the Siege of Terra as originally told in older sources with that of the Black Library novel series. Most notably these include:

  • In the original lore, Lorgar himself led the Word Bearers on Terra.[Needs Citation] However as of the events of the novel Slaves to Darkness, Lorgar is banished from Horus' sight for attempting to usurp him and instead the Word Bearers at Terra were led by Zardu Layak.[4]
  • The Iron Warriors did not evacuate midway into the siege.
  • Kharn the Betrayer was not slain by Sigismund.
  • Mortarion was not banished back to the Warp in a duel with Jaghatai Khan.
  • Dark Angels did not land at the Astronomican.
  • The Sky Fortress was used for the defense of the Eternity Gate, not for the retaking of the Lion's Gate Spaceport by Jaghatai Khan.[1d]
  • Magnus was not defeated by Vulkan, and likewise Angron was not defeated by Sanguinius.[22f]

See also


Battles of the Horus Heresy
005-006.M31 Battle of Isstvan IIIFirst Battle of ProsperoWar Within the WebwayBattle of the Somnus CitadelUnrest on CalibanSchism of MarsBattle of DiamatDrop Site MassacreBattle of the Rangda SystemFirst Battle of ParamarManachean WarSignus CampaignTreachery at Advex-MorsSiege of Cthonia
007-008.M31 Battle of PhallBattle of RavendelveRuin of MaedranBattle of the Alaxxes NebulaPale Stars CampaignBreaking of the Perfect FortressChondax CampaignSecond Battle of ProsperoFirst Siege of Hydra CordatusBattle of the Furious AbyssBattle of CalthBattle of ArmaturaBetrayal at IthracaDeath of CanopusShadow CrusadeCrusade of IronDoom of BorminaDefence of TyrosDefence of the Three PlanetsBattle of UlixisAmbush at EspandorBattle of Aquila AtollBattle of Drooth IIPercepton CampaignBattle of IydrisThramas CrusadeFall of Baztel IIIBattle of VannaheimSecond Battle of ParamarBattle of Constanix IIMezoan CampaignBattle of BodtBattle of DwellErellian SubjugationSiege of Baal
009-010.M31 Battle of MolechBreaking of AnvillusXana IncursionCarnage of MoroxSangraal CampaignBattle of ArissakBattle of PerditusBattle of SothaDrussen AtrocityScouring of Gilden's StarBattle of NyrconBattle of TallarnCataclysm of IronBattle of NocturneBattle of PlutoSiege of InwitBurning of Ohmn-Mat
011-014.M31 Lorin Alpha CampaignSubjugation of TyrinthMalagant ConflictBattle of the Kalium GateBattle of CatallusAxandrian IncidentBattle of TralsakTarren SuppressionBalthor Sigma InterventionBattle of AbsolomScouring of the Ollanz ClusterBattle of ZepathSecond Battle of ZaramundBattle of AnuariBattle of PyrrhanSecond Battle of DavinArgolian MassacresBattle of TrisolianBattle of YarantBattle of KradeBattle of DelugeBattle of Heta-GladiusBattle of the Aragna ChainBattle of KallethBattle of the Diavanos SystemBattle of DesperationBattle of Beta-GarmonDefence of RyzaBattle of ThagriaPassage of AngelsThassos IncidentBattle of Zhao-ArkhadSerpent's CoilSiege of BarbarusBattle of VezdellBurning of VrexorDawn of DesolationDeath of ChemosBattle of Luth TyreYdursk IncidentSolar WarRaid on LunaSiege of TerraGreat Scouring