Battle of Isstvan III
"Order the guns to fire! Let the galaxy burn!"
The Battle of Isstvan III (also referred to as the Isstvan III Atrocity[1c][1d]) was the start of the Horus Heresy and was fought between the Adeptus Astartes loyal to the Emperor of Mankind and those traitors that swore fealty to Warmaster Horus.[1a]
Contents
Overview
The Isstvan Conspiracy
Over a year before the battle, Warmaster Horus Lupercal had fallen on the moon of Davin thanks to a conspiracy by the Word Bearers.[3] He immediately set about constructing a plan to overthrow the Emperor. Still posing as the loyal Warmaster of the Throne of Terra, Horus weaved a web of deceit and betrayal in preparation for open rebellion. This included sending Primarchs deemed likely to remain loyal such as Lion El'Jonson, Roboute Guilliman, and Sanguinius to the fringes of the Imperium to ensure they could not interfere with what was about to transpire. Meanwhile, he assembled those Legions whose Primarchs he had managed to turn to his cause: Fulgrim and the Emperor's Children, Angron and the World Eaters, and Mortarion of the Death Guard, planning to use the coming battle as a way to purge this force of remaining loyalist elements.[1a]
So it was that some 200,000 Astartes assembled in the Isstvan System, ostensibly to counter an anti-Imperial rebellion on Isstvan III. The Death Guard Legion had received a distress signal from Isstvan III which stated that the colony had turned away from the Imperial Truth and that the former governor, Vardus Praal, was leading the rebellion. The assembled Imperial expedition was tasked with eliminating this threat. While Mortarion and Angron were able to rendezvous with Horus at Isstvan III, Fulgrim was dispatched to potentially turn Ferrus Manus to the traitor cause and the Emperor's Children at Isstvan were commanded by Lord Commander Eidolon.[1a]
War against the Isstvanians
Initial skirmishes were fought on the outer system world of Isstvan Extremis where the Emperor's Children and Death Guard had managed to eliminate the enemy outpost. With the enemy forces blinded, Warmaster Horus brought about the Legions to hammer the rebel forces.[1a][1b]
However, Isstvan III would be no easy conquest. The world was heavily defended against any outside incursion, and the rebels possessed powerful Psyker-warriors dubbed Warsingers.[1g] So it was that a massive Drop Pod assault was launched onto Isstvan III's surface. Four primary targets were chosen for this attack at Isstvan's capital dubbed the Choral City. The Emperor's Children would land at the Precentor Palace where the traitorous governor was believed to be, the World Eaters at the central plaza, and the Death Guard at the outer bunker network. The final and most difficult target would fall to the Sons of Horus, which would land east of the city at a vast ancient complex dubbed the Siren Hold. It was here that the most Warsingers were believed to be based.[1g]
The first wave of Drop Pods fell upon the Choral City like hammer blows, landing after a brief but intense orbital bombardment. The first to land were the World Eaters at the city surrounding Precentor's Palace, who smashed into the central plaza and killed everything in their path. While quickly capturing the plaza, the battle for the Precentor Palace would prove far more difficult due to its heavy defenses which had been designed by Imperial military architects. It was here that the Emperor's Children next landed, using Dreadnoughts and Melta Gun-armed infantry to burst into the palace and fight their way through each level. Meanwhile, the Death Guard managed to quickly overrun the western fortification line against half-insane mutated Imperial Army rebels. Led personally by Mortarion, the Death Guard quickly silenced the rebels Basilisk guns and Malcador heavy tanks before pushing through the trench and bunker networks. These assets were given heavy air support alongside a compliment of the Legio Mortis.[1g] Due to incorrectly mapped locations, many of the drop pods that crashed at Choral City slammed into the city's towers which caused a delay in reinforcements as they were pinned in inaccessible locations. The Titan Dies Irae was also present at the planet and made use of its mighty weapons to eliminate heavy enemy positions.[2c]
At the Siren Hold, the Sons of Horus landed in a labyrinth of lesser shrines, arches, and walkways. The Sons of Horus were quickly scattered amidst this ocean-like edifice and came under heavy fire.[1g] A more dangerous threat to the invading Astartes were the Warsingers which managed to kill dozens of Space Marines each with their sonic songs.[2c] It was at this point in the battle that an enormous scream erupted across the Choral City and beyond, driving the people of Isstvan III into uncontrolled hatred and madness and driving them to resist the Imperials by any means necessary. All four Space Marline Legions now had to contend with waves of frenzied civilians in addition to the standard rebel troops.[1g]
At the Precentor Palace, the Emperor's Children advanced room by room at significant cost thanks to the presence of many Warsingers. There were also large numbers of a previously unencountered type of rebel elite. These warriors were surgically modified and mutilated, clad in black vitrified armour, and wielding strange weapons that spat killing blasts of sound or darts of liquid metal. However they eventually were able to fight their way to the throneroom, where Captain Lucius slew the heavily augmented Vardus Praal personally.[1h][2d] Simultaneously deep within the Siren's Hold Tomb Spires the Sons of Horus under the command of Garviel Loken fought into a strange corpse-filled shrine and slew many Warsingers before destroying the complex. These two acts managed to dispel the strange cacophony that held sway over the Choral City, and within hours the rebellion was smashed. Quickly securing their remaining objectives, the victorious Space Marines celebrated their hard-won victory, unaware that disaster was about to strike.[1h]
Betrayal
With those squads and their leaders that were known to be completely loyal to the Emperor on the planet, the Warmaster finally decided to initiate his plan. All communication with the orbiting fleet ceased and the Titans of the Legio Mortis went silent as they sealed themselves against biological threats.[1h] The warships Vengeful Spirit, Firebird, Andronius, Killing Star, Indomitable Will, Gauntlet of Spite, Warchild, Eisenstein[4a], and Conqueror all lowered into low orbit and launched salvos of Virus Bombs upon Isstvan III's surface.[1h] The assembled Remembrancer Order was present on the Vengeful Spirit while this happened. After Horus declared his intentions of overthrowing the Emperor, his Astartes went about exterminating the Remembrancers.[2a]
Each virus bomb contained thousands of submunitions, each of which contained deadly Life-Eater Virus. These sub-warheads detonated in the lower atmosphere and rapidly spreading the phage across the surface. The Life-Eater was one of the most insidious and terrible weapons forged by Mankind, and every piece of organic matter it encountered rotted into liquid refuse within seconds. Billions of Isstvanians died in agony alongside all of the planets flora and fauna. Even the oceans turned into a greenish sludge as all organic matter within rotted away. But the destruction was not over yet. The Life-Eater was intentionally designed so that the miasma caused by its victims transformed into a highly flammable gaseous sludge. At Horus' command, a single Lance strike was launched from orbit, detonating this toxic stew and engulfing the planet in a tsunami-like firestorm. The resulting inferno engulfed the entire surface of Isstvan III, incinerating its now-empty cities. All that remained of Isstvan III in the afterlife was a dark dead planet.[1h]
Meanwhile in orbit, many vessels fell into anarchy as loyalist elements resisted the unfolding treachery. The Torpedo-monitor Ducroix turned its guns upon the traitor armada before being torn apart by retaliatory fire. The Heavy Cruiser Sunstone was the site of an intense battle between loyalist and traitors who fought each other on every deck, eventually suffering a reactor meltdown and exploding. The Mechanicum Ordo Reductor War Galley Xerxes 9-7-7 refused an order to surrender to Horus and was shot down onto Isstvan III's surface.[1i] Surprisingly, elements within the vessel survived the crash and fought alongside the loyalists under Magos Reductor Calleb Decima.[1m]
But even before the first Virus Bombs had been launched, Horus' plan had already begun to unravel. Unknown to him, several loyalist officers within the armada had learned of the treachery and managed to warn the Space Marines on the surface. Chief among these were Nathaniel Garro of the Death Guard and Saul Tarvitz of the Emperor's Children. Warned of the impending disaster, some 90,000 the Sons of Horus, World Eaters, Death Guard, and Emperor's Children on the surface managed to seal themselves away inside the remaining bunker and catacomb networks on Isstvan III. Thanks to the warnings given by Garro and Tarvitz, some 2/3rds managed to survive the bombardment, though most of the accompanying Imperial Army, Mechanicum troops, and Administratum functionaries were not so lucky. Meanwhile, Garro was able to wrest control of the Eisenstein with his loyalist Death Guard and escape the Isstvan System for a perilous journey to Terra to warn of the treachery.[1i]
While most of the Astartes had survived in their shelters, a shock fell over them. Never before had such a terrible betrayal befallen the Legiones Astartes, and worse still their own Primarchs had disowned them. This shock soon turned into righteous defiance, and the remaining survivors pledged to fight to the last and not go down silently.[1b] But before Horus could formulate a new plan, the maddened Angron unexpectedly descended from the Conqueror to Isstvan III with 50 companies of frenzied World Eaters, intent on massacring the loyalists. The recklessness and insubordination infuriated Horus, who no longer could simply annihilate Isstvan from orbit without eliminating a key commander for his coming wider rebellion.[1b]
Last Stand
Seeing that they were betrayed, Captains Garviel Loken and Tarik Torgaddon of the Sons declared to the surviving Astartes of the XVI Legion that they were once again the Luna Wolves and marched to Praal's stronghold, where they dug in with the surviving members of the Emperor's Children under Saul Tarvitz and Lord Commander Abdemon[1j] and combated against the traitor forces.[2e] The loyalist World Eaters fell under the command of Captain Ehrlen and Centurion Shabran Darr[1k] while the Death Guard survivors were led by Crysos Morturg. The loyalists pledged to make their traitorous brothers pay for every inch of ground.[1h]
The first ground combat between loyalist and traitor saw Angron and his berserkers charge headlong into a bunker complex defended by some 2,000 loyal World Eaters under Ehrlen. Both sides succumbed to their Butcher's Nails and the battle soon erupted into a chaotic melee. During the fighting, Ehrlen was overcome by dozens of his former brothers and torn apart.[1b][1l] Nearby in the remains of the Choral City plaza, 7,000 World Eaters butchered one another in a frenzy of violence. But Angron was an avatar of carnage, and the Primarch's presence allowed the Traitors to emerge victorious at unexpectedly heavy cost. Perhaps surprisingly, Angron seemed pleased with the contest that had erupted and is said to have yelled "It is well done!" before moving on in search of new foes to butcher.[1l]
With destroying Isstvan from orbit no longer an option and knowing Angron needed support against the surviving loyalists, Horus had no choice but to launch his armies back upon the surface of Isstvan III for a protracted struggle. The Emperor's Children under Eidolon were the next to deploy, landing near the scorched remains of the Precentor Palace and meeting fierce resistance from Tarvitz's loyalist Emperor's Children. Instead of finding confused survivors, the traitors encountered skilled and determined resistance and were forced to retreat, leaving dozens of damaged or destroyed vehicles in their wake. The rechristened Luna Wolves under Loken and Torgaddon launched a series of successful hit-and-run ambushes that decimated their traitorous brothers.[1m] The traitors next tried to use their air superiority to their advantage, but gunships and aircraft were vulnerable to ground fire and many loyalists would simply wait in hiding for them to pass on. Remaining loyalists were present even in the traitor fleet, as demonstrated when the Sons of Horus Strike Cruiser Minotaur was destroyed when a Storm Eagle unleashed its payload inside its hangar bay, its crew broadcasting "avenge the blood of Terra!" before choosing suicide over treachery. While Horus had succeeded in the initial phase of his plan to separate his traitorous Legions from their loyalist elements, the entire campaign soon spiraled into a disaster.[1l]
In the ensuing months of bitter fighting, the defenders made the traitors pay for every piece of ground gained. Eidolon launched multiple attacks upon the Precentor Palace but each time was beaten back by Tarvitz and his Emperor's Children. The Venerable Dreadnought Rylanor fought alongside Tarvitz, gaining infamy in the battles. Many times Rylanor was thought destroyed, only to always rise again and reap carnage upon the enemy.[1m] In one engagement, Eidolon was forced to scurry away after the loss of his Chaplain Charmosian.[2e] Meanwhile, Loken and Torgaddon continued their strategy of mobile defence, proving too elusive to encircle and pin down. Roving bands of loyal World Eaters continued to harry the traitors, and to the northwest the loyal Death Guard stubbornly fought on in an intact bunker network.[1m]
However despite the determined and skillful loyalist resistance, their foes were too many and too well-supported by heavy armour, air power, and Titans of the Legio Mortis. It was only a matter of time before they were dwindled down to nothing by sheer attrition. The defending loyalists were well aware of this reality and had no delusions of surviving the coming struggle, but this did nothing to shake their determination to resist their foes. The only benefit that the loyalist could take advantage of was the eruption of violent storms across Isstvan III that were brought on by its destruction. These storms served to further delay the traitor advance.[1l] By two months into the conflict some 10,000 loyalists were believed dead, but they had inflicted twice that upon the traitors.[1m]
The first cracks in the loyalist defense came from the Death Guard in the northwest of the Choral City, who were faced with the most desperate situation as both Angron and Mortarion each advanced on their position. Already hammered by the vicious frontal assault of the World Eaters, Mortarion landed his great relic assault ship Omen and used its turrets to sweep the ground clear of trenches and pillboxes. In their wake came heavy Spartans, Fellblades and Typhon tanks with Mortarion personally leading them. One by one, the loyalist defensive bastions were subdued.[1m]
Endgame
Nearly two months into the fight, the last of the great storms began to wane and the loyalist situation rapidly worsened. Tarvitz and his Emperor's Children still held the Precentor's Palace and the Luna Wolves still held the Siren's Hold, but in the northwest the loyal Death Guard were finally smashed by Mortarion and Angron's onslaught. In a confusing battle dubbed the "Veil of Grief", the legendary discipline of the Death Guard broke down as some surviving loyal elements within Mortarion's own armies turned their guns upon their traitorous brothers or the World Eaters. Traitor and Loyalist became lost in the maelstrom, with Death Guard Marshal Durak Rask being killed by Crysos Morturg. Mortarion himself is said to have been wounded in the battle, burned by plasma fire from one of his own Predator tanks before he and his Deathshroud hacked it to pieces. The respite the confusion brought allowed some of the surviving loyal Death Guard to withdraw. In the aftermath a spiteful Mortarion used the waning storms to land massive amounts of reinforcements and poured heavy armour and Titans into the area, annihilating what resistance they still encountered. The loyalist Death Guard did not give up however, and withdrew to subterranean bunker and catacomb networks to continue to fight on. Mortarion had expected this however, and brought in Vortex charges and Hades Breaching Drills to clear out these remaining bastions.[1m]
Meanwhile at the Choral City, Horus unleashed Abaddon and his elite Justaerin to the southwest. Backed by heavy armour, airpower, newly christened Dark Mechanicum troops, and Titans, they flushed out and wiped out what resistance was encountered. Shockingly, the traitorous Sons of Horus were accompanied by the witch-priests of Davin's Serpent Lodge, who used the power of the Warp to unleashed a sickening shroud across the battlefield.[1m]
Eidolon launched another assault on the Precentor's Palace, this time backed up by freshly landed Titans of the Legio Mortis and Legio Audax.[1n] Formerly loyalist Captain Lucius had grown to despise Saul Tarvitz and wanted to rejoin his Legion. Using a slain Chaplain's helmet communicator, he contacted Lord Commander Eidolon and arranged for the betrayal of his comrades. Lucius himself had slain all the defenders at that part of the encampment promising Eidolon not only glory by defeating the loyalists but giving him the head of Saul Tarvitz. Despite his boast, Lucius was defeated when Tarvitz had reinforcements, forcing Lucius to flee back to the Emperor's Children Legion.[2f] Meanwhile, the traitor Titans combined their fire on part of the structures wall, finally blowing a hole in the structure and allowing them to advance inside for the first time. The first into the breach however was not the traitorous Emperor's Children however, but Angron and his World Eaters who massacred any remaining loyalists encountered inside.[1n]
To the northwest at the Siren's Hold, Abaddon's Justaerin came into contact with Loken and Torgaddon's Luna Wolves after landing via Caestus Assault Rams.[1n] Backed by gunships and heavy armour, Abaddon's Terminator elite were finally able to break their way into the Siren's Hold. Hopelessly outnumbered and outgunned, the Luna Wolves fought to the last but the Siren Hold fell within the hour.[1n] Despite a valiant final battle against Abaddon and Horus Aximand, Torgaddon was slain and Loken was buried under rubble from a Titan's blast.[2b] The traitors unleashed Phosphex into the lower catacombs, burning those who remained below alive as Davinite Priests used their dark arts to identify any living who remained. By now, the war had devolved into a hunt for the small pockets of remaining loyalists who were all eliminated to a man.[1n]
There were ultimately only handful of loyalist survivors, such as Loken,[5] Morturg and Decima,[6] and Rylanor, who unknown to all sides remained hidden on the planet for millennia after.[7]
Aftermath
While victorious, the battle had proven far more costly and time-consuming than Horus could have envisioned. Moreover, by this point Fulgrim had finally returned with troubling news. Ferrus Manus had refused to join their cause and it was only a matter of time before their treachery was discovered by Terra. Horus finally withdrew his forces from Isstvan III, leaving an utterly dead world behind. He immediately set about for the next phase of his reformulated plan, regaining the initiative with an even greater act of treachery at Isstvan V.[1n][2b]
Gallery
See also
Sources
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- 1: The Horus Heresy Book One - Betrayal:
- 2: Galaxy In Flames (Novel)
- 3: False Gods (Novel) - Chapter 17
- 4: The Flight of the Eisenstein (Novel)
- 4a: Chapter 8
- 5: Garro: Legion of One (Audio Book) - Garro's Arrival
- 6: Blackshield (Short Story)
- 7: Sons of the Emperor (Anthology) — The Ancient Awaits
