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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.
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
SalamandersSymbol.jpgPrimarch Vulkan (Hidden)[14]
Custodesflag.JPGCaptain-General Constantin Valdor
Impfistslogo.pngFirst Captain Sigismund
Bloodangelslogo.pngFirst Captain Raldoron
Bloodangelslogo.pngGuard Commander Azkaellon
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]
White Scars Symbol.pngLord Commander Qin Fai Noyan-Khan[13]
White Scars Symbol.pngCaptain Shiban Khan (WIA)[13g]
White Scars Symbol.pngChief Stormseer Naranbaatar[13d]
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.jpgHigh Primary Solar General Saul Niborran (KIA)[13]
Imperial Army Symbol.jpgMilitant General Konas Burr (KAI)[13]
Imperial Army Symbol.jpgLord Commander Militant Adreen
Imperial Army Symbol.jpgMistress Tacticae Katarin Elg
Imperial Army Symbol.jpgMarshal Aldana Agathe[13]
Imperial Army Symbol.jpgGeneral Yennu Egwu[10j] (defects)
Imperial Army Symbol.jpgGeneral Nasuba
Imperial Army Symbol.jpgMilitant Colonel Clement Brohn
SoSSymbol.jpgKnight-Commander Jenetia Krole (KIA)[13g]
Luna Wolves Legionssymbol.jpgCaptain Garviel Loken[13f]
Captain Nathaniel Garro[13f]

SoHSymbol.jpgWarmaster Horus Lupercal (KIA)

IWPreHeresySymbol.jpgPrimarch Perturabo
WEPad.jpegPrimarch Angron
ThousandSonsPad.jpgPrimarch Magnus the Red
EC Symbol.jpgPrimarch Fulgrim (AWOL)
DGSymbolNew.jpgPrimarch Mortarion
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]
WBSymbolNew.jpgDark Apostle Zardu Layak (KIA)[10j]
DGSymbolNew.jpgFirst Captain Typhus
WEPad.jpegCaptain Khârn (WIA)
ThousandSonsPad.jpg First Captain/Chief Librarian Ahzek Ahriman
IWPreHeresySymbol.jpgWarsmith Forrix[10j]
IWPreHeresySymbol.jpgWarsmith Kroeger[10j]
IWPreHeresySymbol.jpgWarsmith Barban Falk[10j]
IWPreHeresySymbol.jpgWarsmith Ormon Gundar[13f]
IWPreHeresySymbol.jpgWarsmith Bogdan Mortel[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
Nurgle mark.pngDaemon Prince Cor'bax Utterblight
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

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 was severely wounded and a third (Vulkan) was 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 Palace Walls, 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 fourteen 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 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 19th 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. 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 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 a breach in the walls was created after the Thousand Sons detonated a Nuclear Weapon, but at the last minute they 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]

The Adeptus Custodes battle Daemons at the Imperial Palace

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]

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] Meanwhile, while the traitor army had been battering at the Palace walls, Jaghatai Khan and his White Scars Legion had been busy harassing their flanks in a series of hit-and-run attacks. Now the Khan changed plans and launched a lightning nighttime raid on the Lions Gate Spaceport in cooperation with the 1st Terran Tank Division of the loyalist Imperial Army, easily overrunning the traitor garrison and reclaiming the port in the name of the Emperor. The attack managed to slow the Traitor advance on the Imperial Palace.[1c] In addition, Horus ordered the Death Guard to pull back from the assault on the palace to deal with the White Scars.[2]

Under Perturabo's command, a combined assault was launched that finally saw a traitor breakthrough. Perturabo combined an underground assault in tunneler drills with a pinpoint Chaos titan Macrocannon bombardment.[2] The walls of the Emperor's Palace finally broke, unleashing a flood of traitors into the inner courtyards of the Palace. A massive labyrinth of hallways, complexes, courtyards, and buildings, fighting in the outer palace was room-to-room and saw heavy casualties inflicted on the Traitors.[2] Moreover, the inner sanctum of the palace had been heavily reinforced and in the enclosed spaces Traitor titans and heavy war engines became easy prey for the well-prepared loyalists. The Adeptus Custodes made a fierce counterattack at the inner gardens of such brutal efficiency that none of the traitor horde could initially stand against them. However, in the end, the Titans of the Legio Mortis proved decisive in a traitor breakthrough. In addition, traitor numbers were too great and even the Custodes were overwhelmed. After inflicting horrendous casualties on the traitor forces, so much so that the Chaos Titans could no longer continue to advance,[2] the Custodes would fall back to the final defensive line around the Imperial Palace, the Eternity Gate, manned by the Blood Angels and their Primarch Sanguinius. Perturabo and his Iron Warriors, their job of creating a breakthrough for the other Traitor Legion forces done, left the battle for the Inner Palace to instead direct a siege against the Imperial Fists Fortress Monastery nearby.[2]

Magnus the Red and the Thousand Sons joined the battle, attacking the Ultimate Gate of the inner sanctum of the Imperial Palace in conjunction with a horde of Khorne Daemons and World Eaters.[2] As traitorous hordes swarmed towards this final bastion of defense, Sanguinius himself became locked in mortal combat with a mighty Bloodthirster of Khorne, Ka'Bandha, the daemon he had battled at Signus Prime. After a protracted and bloody airborne struggle above the Ultimate Gate, the Primarch broke the Daemons back over his knee.[1c] The defending Blood Angels and Custodes forces were reinforced by the Imperial Fists led personally by Rogal Dorn, which disembarked from the great Sky Fortress, a massive fortified orbital plate. Though it managed to deliver withering fire and much-needed reinforcements to the loyalist forces and stopped an attempt by Thousand Sons Sorcerers to destroy the inner sanctum in an arcane ritual[2], in the end, the Sky Fortress was shot down by the Titans of the Death's Head legion. The ensuing crash detonated the ship's great plasma reactors, creating an explosion that ripped a forty three kilometer wide crater outside the palace. Though the blast had wiped out massive numbers of traitors, the loyalist forces now realized that they were cut off from the rest of Earth.[1c]

Sanguinius and his Blood Angels during the Battle of Terra

The Vengeful Spirit

However, despite these gains, the situation soon changed for the worse for Horus. He received news from his daemonic allies that the Space Wolves and Leman Russ had evaded the Alpha Legion, the Ultramarines under Roboute Guilliman had defeated the Word Bearers at Calth, and the Dark Angels under Lion El'Jonson were also Terra-bound. Horus was furious at the news. He had gambled everything on being able to defeat the forces of Terra before the Emperor could muster help from all the still-loyal Legions. With time against him, it now appeared that the gambit had failed and came up with an even riskier gambit. Lowering the teleportation-inhibiting Void Shields on his Battle Barge, Vengeful Spirit, Horus in effect invited the Emperor to come to him.[1d]

Despite objections by Rogal Dorn, the Emperor decided to willingly fall into Horus' trap knowing all to well what awaited him. Leaving management of the Golden Throne to his trusted subordinate Malcador, the Emperor, Dorn, Sanguinius, as well as an elite force of Space Marine Terminators and Adeptus Custodes teleported directly into the Vengeful Spirit. However, the teleportation process had malfunctioned and the loyalist forces were scattered throughout daemonically corrupted ship.[1d]

Coming under attacks from all kinds of horrors aboard Horus' flagship, including Daemons, monsters, and Chaos Space Marines, the loyalist forces fought their way across the Battle Barge in search of Warmaster Horus himself. 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.[1d]

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

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] In addition, the Iron Warriors did not evacuate midway into the siege in the original narrative of the battle.


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 Campaign
007-008.M31 Battle of PhallBattle of RavendelveRuin of MaedranBattle of the Alaxxes NebulaSiege of the Perfect FortressChondax CampaignSecond Battle of ProsperoFirst Siege of Hydra CordatusBattle of the Furious AbyssBattle of CalthBattle of ArmaturaBetrayal at IthracaShadow 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 DwellBattle of Molech
009-010.M31 Xana IncursionCarnage of MoroxSangraal CampaignBattle of ArissakBattle of PerditusBattle of SothaDrussen AtrocityScouring of Gilden's StarBattle of NyrconBattle of TallarnCataclysm of IronBattle of NocturneBattle of Pluto
011-014.M31 Malagant ConflictBattle of the Kalium GateBattle of CatallusBattle of TralsakTarren SuppressionBalthor Sigma InterventionBattle of AbsolomScouring of the Ollanz ClusterBattle of ZepathSecond Battle of ZaramundBattle of AnuariBattle of PyrrhanSecond Battle of DavinBattle 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 ThagriaSolar WarRaid on LunaSiege of TerraGreat Scouring