The Mezoan Campaign, also referred to as the Third Siege of Mezoa, was a great battle fought in the opening years of the Horus Heresy. It marked the final concentrated effort of the Traitor Warmaster Horus Lupercal's forces to seize control of the strategically important Mechanicum Forge World of Mezoa, the last star system still loyal to the Throne of Terra in the Gothic Sector. Besieged by elements of both the Alpha Legion and Iron Warriors, Mezoa was only saved through the timely intervention of the Disciples of the Flames, a splinter-faction of the Salamanders Legion.

The Third Siege of Mezoa is a visceral lesson in the remaining effectiveness of the Shattered Legions, those Legiones Astartes who were broken or annihilated at the Drop Site Massacre on Istvaan V and were still able to intervene and hinder the Warmaster's carefully-laid plans. While few at the time saw little significance in the Loyalist's victory, the actions of the Shattered Legions proved successful in slowing Horus' march towards Terra. The Mezoan Campaign also provides one of the few reliable accounts of the actions of Blackshield forces during the conflict.


War in the Coronid Deeps

Following the revelation of the Warmaster's true intent in the Istvaan System, the worlds of the Coronid Deeps were the first to suffer from the Traitors' expansive efforts. Led by the Warmaster himself, the Sons of Horus quickly captured the heavily industrialised Manachean Commonwealth in the short-lived Manachean War, whilst their allies in the Death Guard under the command of their own Primarch Mortarion cleansed the strategically less important Grail Abyss of all life. Most importantly, through the events of the Treachery at Port Maw, the Warmaster captured a sizable Armada Imperialis naval fortress and orbital shipyard which would allow him to rearm and repair his fleets during the long march to Terra. By the end of 008.M31 only a few Imperial domains were spared the wrath of the Traitors' armies. To the galactic west, the isolated worlds of the Agathean Domain were deemed too insignificant to squander valuable military resources on conquering it, while in the Cyclops Cluster the Forge World of Mezoa proved a far too difficult target to assail readily. As the Great Crusade had done centuries before, the Traitors' advance would circumvent Mezoa and blockade it until enough men and resources could be gathered to take the strategically important domain of the Mechanicum.

While many worlds of these far-flung territories were deemed not valuable enough to offer any kind of coordinated resistance or threat -- which at least in the case of the Agathean Domain would prove to be a gross miscalculation -- the Warmaster knew that he could not ignore the powerful Mezoan Mechanicum. However, having challenged his father for the rule of the entire Imperium of Mankind, Horus, the pretender, could not afford to be delayed in the Coronid Deeps, but had to be seen on the frontlines leading new conquests and rallying new star systems to his banner. The task of eliminating the threat posed by the Loyalist Forge World would be handed down to other military commanders belonging to the Warmaster's allies. Yet such a general could not readily be found. Horus' own puppet-ruler, Taloc Thorne, the Tyrant of Port Maw, lacked the military forces to both maintain productivity in the Manachean Commonwealth and conduct a military campaign of the scale required to conquer the belligerent Forge World. Horus' principal ally in the region, the Dark Mechanicum Forge World of Cyclothrathe, preferred to accomplish its own objectives rather than obey Thorne's orders. In truth, only the Forge World of M'Pandex, a long-time rival of Mezoa, showed any devotion to the Loyalists' eradication. But long eclipsed by its rival, M'Pandex too, lacked the military resources to vanquish Mezoa alone. Two previous attempts to seize Mezoa's principal forge-fane had already been repelled, as the Mezoan Magi used their world's own volcanic might against the invaders, letting the ground collapse under the Traitor's landing zones and rerouting lava-streams to stall any advance or burn their enemies to ashes. Some of the most exotic reports of the earlier campaigns from the survivors even told of kilometer-long chunks of solidified magma, essentially man-made asteroids, that had been flung as projectiles at incoming enemy ships. The kinetic impact alone had been powerful enough to break a voidship in two.

The Poisoned Chalice

Autilon Skorr Consul-Delegatus

Autilon Skorr Consul-Delegatus of the Alpha Legion and commander of the Traitor forces during the Mezoan Campaign

Even as the wars of the Horus Heresy unfolded, the defiant Forge World still resisted every attempt at conquest by the Traitors. Words of Mezoa's continued defiance did not fail to reach Horus, and it is said that his wrath was terrifying to behold. Those records captured by the servants of the Emperor in the wake of the Warmaster's defeat attest of a vast armada gathering at Port Maw, where the fleets of those Legions loyal to Horus were refitted and repaired with the materials once intended to ensure the progress of the Great Crusade. It was here that Horus' latest proclamation was presented to his generals -- a formal order to destroy Mezoa. This order was so widely promulgated that several illuminated copies of this manuscript have survived to this day and are actually preserved in both the Imperial Archives of Terra and the Inquisitorial Archives on Tethys.

The elimination of the threat posed by the Loyalist Forge World was a necessity. With his armies mustering for their final push towards the Segmentum Solar, the Warmaster could not allow any potential weakness in his rear, or risk exposing the Traitors' vulnerable supply lines. But however important the conquest of Mezoa, every Traitor commander present at Port Maw knew that victory would only be achieved at a tremendous cost in lives and materiel. As a result of Mezoa's tectonic instability, the powerful God-engines of the Collegia Titanica could not be deployed, dramatically increasing the cost of taking the defiant Forge World. With much glory to be won in the oncoming wars, Horus' commanders were loath to weaken their forces at such an early juncture. Yet, none were so foolish as to openly refuse or ignore the will of the Warmaster.

Knowing that Horus' eyes rested upon them, a silent war of influence erupted between the commanders of the Traitor forces. Through veiled threats, outright lies and no few fatal confrontations, the officers of the Archtraitor's armies each sought to see the mission assigned to one of their rivals. For solar weeks this silent war went on, until the proverbial scapegoats presented themselves at Port Maw. Humbled by their defeat at the hands of the Shattered Legions during the Siege of Epsilon-Stranivar IX -- colloquially known as "Fortress Stranivar" -- the 78th Chapter of the Alpha Legion under their Consul-Delegatus Autilon Skorr and the depleted 114th Grand Battalion of the Iron Warriors arrived at Port Maw. In the absence of their respective Primarchs, both formations lacked influential patronage or an unified officer cadre that would have been able to oppose the alliance of previously established commanders. So it came to pass that these forces would have to take up the poisoned chalice and prosecute the Mezoan Campaign to its conclusion. In recognition of his rank, Autilon Skor was appointed as overall commander of the new taskforce and given access to Port Maw's vast stockpiles of arms and materiel.

Nârik Dreygur The Gravewalker

Ancient Remembrancer sketch of Nârik Dreygur, commander of the 114th Grand Battalion of the Iron Warriors Legion

Even in the wake of his defeat on Stranivar, Autilon Skorr's ambition was undimmed. Being fully aware of the enmity borne for him by most of the command elements of the 114th Grand Battalion, Consul-Delegatus Skorr used his new position as commanding officer of the Mezoan taskforce to appropriate the lion's share of the available resources for his own 78th Chapter, leaving the Iron Warriors elements under Nârik Dreygur little chance to recover from their previous losses. With the bulk of the IV Legion and their volatile lord, the Primarch Perturabo, deployed far away, Dreygur's pleas for help or materiel fell on deaf ears, the other commanders seeing little interest or profit in aiding one they regarded as a failed officer. With no other choice left to them, Dreygur and his Iron Warriors had to make what repairs they could and tend to their wounds, their resentment against Skorr growing even deeper.

Composed of a dozen capital class warships -- including a pair of the fearsome Mangonel-class Bombardment Cruisers, 9,000 Legiones Astartes, three full Taghmata from the Renegade Forge World of M'Pandex and 20,000 auxiliary troops, the Mezoa task force was one of the largest battlegroups assigned to an independent command that was not under the control of a Primarch. Knowing that victory in this particular theatre of war would ensure gaining the favour of the Warmaster, an invaluable commodity once Horus sat upon the Golden Throne, Autilon Skorr began his preparations. Departing in good order, the fleet entered the Warp, the Davinite Lodge Priests attached to the fleet's Navigator-contingent assuring Skorr that their passage would be swift and sure and cleared of all storms. In a few short solar days, the fleet entered the Mezoa System, but they soon discovered that they were not the first to arrive...

Devils from the Outer Dark

"All things must be tested upon the anvil and beaten until the heart of their being is exposed and measured. This is true of loyalty as it is of steel, for loyalty that is never tested is as worthless as flawed metal."
— Codicil 13:9 of the Book of VulkanAs one of the few bastions of Imperial resistance, the Forge World of Mezoa had been reinforced by splinter forces of the Shattered Legions and even Loyalist survivors of the Armada Imperialis which had been present at the Treachery at Port Maw. While welcome, these reinforcements failed to considerably alter the balance of strength. The mighty Forge World, a glowing ember encircled by a dense ring of orbital defence stations and kill-satellites, could not hope to match the Traitors' numbers. Even worse, Autilon Skorr had learned his lessons from the fiasco at the Siege of Epsilon-Stranivar IX and ensured that all his voidships' captains would obey his word, while the Loyalists' command -- even though united by a common goal -- was fractured. Nevertheless, the rag-tag Loyalist fleet bravely opposed Skorr's attempts to gain local space superiority. Soon, a chaotic void battle developed where the vessels of the Iron Warriors and Alpha Legion -- numbering more heavy Cruisers -- started to gain the ascendancy. It was then that a new force emerged unheralded from the Warp at the very edge of the Mezoan System. Unsure as to which side the newly arrived ship would declare its allegiance, the battle ebbed, no new explosions illuminating the void as both sides turned their powerful Augur banks toward the unidentified warship that had emerged behind the Traitors' battleline.

On the bridge of the lone Legiones Astartes Strike Cruiser, the sensor and Vox-operators strove to make sense of the myriad jumbled identification markers and hails broadcast by the combatants. Several tense solar seconds passed while the ship's command crew tried to distinguish friend from foe, a period of time that could have seen the lone Cruiser quickly crippled had its arrival not plunged the Traitors' fleet into total disarray. With the situation now clear, the crew of the Salamanders Strike Cruiser Ebon Drake unleashed its batteries at the closest Traitor vessel, trying to manoeuver its way to join the Loyalist fleet standing sentinel over Mezoa.

Even with the arrival of the Ebon Drake, the Loyalists remained at a serious disadvantage in terms of both numbers and tonnage, but the Salamanders' arrival had disrupted the enemy advance and so the void-battle raged on for more than nine solar hours, both sides locked in a bloody stalemate. In the end, Skorr's unified command broke the balance, the Loyalists' fractious nature causing some ships to retreat and thus leaving their allies unsupported. Rather than face annihilation, the combined Loyalist fleet had to abandon the orbital space around Mezoa, regrouping at the system's outer planets. Several vessels, amongst them the Ebon Drake, chose to dare the enemy fleets' guns one last time and close with the Forge World, risking being crippled to release fights of landing craft and Drop Pods intended to reinforce the defenders on the ground. Of the half dozen Legion and Armada Imperialis vessels to attempt the manoeuvre, only three rose again, the rest were annihilated by the Traitors' guns. With the Loyalist fleet in full retreat, no one could stop the great Mangonel-class Bombardment Cruisers and wallowing troop barges from closing with the Forge World, as Mezoa's orbital defences were soon swept clear by the combined fire of the Alpha Legion and Iron Warriors. The final invasion of Mezoa had begun.

The Gift of Mezoa

Disciples of the Flames

An unidentified Salamanders Legionary of the Disciples of the Flames

High above Mezoa, their path now unimpeded, the Bombardment Cruisers and troop transports carrying the Traitors' moved into position, while on the ground Battlegroup Revenant, comprised of the recently disembarked Shattered Legionaries from the Ebon Drake, gathered around their leader, Cassian Vaughn, former Legion Commander of the Salamanders' Legion in the days before its reunification with its Primarch Vulkan. Believed slain during the Drop Site Massacre, Vaughn had been unearthed by his brothers of the XVIII Legion and his armoured body had slowly but steadily self-repaired thanks to the techno-arcana crafted by Vulkan and his internment within the Dracos Revenant sarcophagus of this uniquely powerful Dreadnought. The Venerable Dreadnought, now known as Cassian Dracos, had led his Disciples of the Flames to Mezoa's central forge-fane. There, the twice-dead former master of the XVIII Legion had met with the Norn-regents of Mezoa, a triad of truly ancient Mechanicum Archmagi-sisters so interlinked by complex neural interface technology that for all intents and purposes they formed a single entity which directed the vast domains of Mezoa. This historic meeting was immortalised by Mezoa's scribe-adepts and still remains in the data-archives of Mezoa ten thousand standard years later. The fire-blackened and battered armoured sarcophagus of Cassian Dracos, the The Avatar of the Sacred Flame, confronted the deadly thin forms of the Norn-regents, each one of the three Magi suspended like spiders in the complex web of arcane cybernetic technology that allowed them to communicate and direct their thralls all across Mezoa. None could deny that the changed Cassian Dracos exerted some strange influence on every automata in his vicinity, for when he penetrated the Norn-regents throne-room, even the regents' personal bodyguard, towering and powerful Domitar-class Battle-Automata, fell back in halting steps, and who can say if the Norn-regents themselves were not somehow influenced by Dracos' new aura?

Bray'arth Ashmantle 2

Cassian Dracos, "the Fallen Master," first Legion Commander of the XVIII Legion and first inhabitant of the unique Dracos Revenant Venerable Dreadnought sarcophagus

Before the Norn-regents, Cassian Dracos spoke of his visions and of the trials he had endured as he lay buried under the black sands of Istvaan V. He told them of his search for Vulkan and his conviction that the Primarch of the XVIII Legion had yet cheated death. Cassian's tale of woe and sacrifice doubtlessly moved the Norn-regents, as the Salamanders' legendary tenacity somewhat echoed the Path of the Flame Eternal, the strange schismatic creed of the Cult Mechanicus honoured by both the Magi of Mezoa and the Hierarchs of House Hermetika. However, these similarities in belief and common loyalty to the Emperor of Mankind seemed a rather slim basis for the accord that would be signed by Dracos and the Norn-queens of Mezoa. In this agreement, Cassian Dracos was formally recognised as a living avatar of the Machine God and given command over Mezoa's sizeable Taghmata and its allies. For the dour Tech-adepts of the Mezoan forge-fanes, the unexpected arrival of a prophet of the Omnissiah was marked as a sign of their impending victory. Imperial scholars in later millennia have often wondered at the sudden acceptance with which Dracos was met by the different groups and factions he encountered. Some even suggested that this outcome might in some way be related to an ability bestowed by the Warp, as Istvaan V's position at the time of Cassian Dracos' near-death had it located at the heart of one of the fiercest Warp Storms in human record. Given the immense amount of blood shed during the Drop Site Massacre and its effects on the powers of the Warp, who can say for sure that the baleful powers of the Warp had not had a more serious effect on the entombed Dreadnought?

Whatever the truth, this alliance would prove beneficial for both parties. Unable to deliver the products of its forges to those Imperial units prosecuting the Great Crusade as they were intended to, Mezoa's storage vaults harboured a true fortune in suits of Power Armour, weapons, ammunition and armoured vehicles to which the Disciple of the Flames and other Loyalist survivors were now given access. In defiance of the ancient treaties negotiated with distant Mars and Terra which regulated who and in what quantity someone might receive the labour of Mezoa's forges, Battlegroup Revenant was entirely reequipped with the very finest of Mezoa's creations. Where previously most of the Shattered Legionaries could only rely on their own personal Bolters and those few man-portable heavy weapons they had brought with them, the Disciple of the Flames and their allies now had access to large stockpiles of armoured vehicles and personnel carriers, including the advanced command version of the venerable Rhino STC, the Damocles Command Rhino, which had only recently been approved for construction and had as yet not been delivered to any of the Space Marine Legions.

The greatest gift of all was perhaps a handful of newly-completed Glaive Super-Heavy Special Weapon Tanks initially intended for the IX Legion. Most notoriously, one of their number, the Dragon Eternal -- crewed by Xiaphas Jurr's Disciple of the Flames -- would defend the Septurn Gateway of Mezoa's principal forge-fane for more than four solar hours after an Alpha Legion diversionary attack had drawn away the gate's other defenders. Attended by the most skilled of Mezoa's forge-wright, the Iron Dragon withdrew to the deepest and most sacred fanes of Mezoa in order to receive the benedictions of the Machine God that would mark his ascension at the head of the Mezoan Taghmata.

The Archmagi were also confident that they would be able to restore Cassian Dracos to his former glory, allowing the newly appointed Avatar of the Sacred Flame to walk again upon the battlefield. While outside the Traitors' dropships blackened the sky, it fell to Lieutenant-Chaplain Xiaphas Jurr to lead the Disciples of the Flames in battle against the attackers. However, they would not face the enemy alone. With them stood those members of the Iron Hands and Raven Guard Legions who had already travelled with them aboard the Ebon Drake, as well as forty-eight Astartes of the Imperial Fists, the survivors of the VII Legion's garrison on Manachea Lux whose flight had ended at Mezoa. Similarly, the 891st Lethe Cohort of the Solar Auxilia had also been drawn to the still-resisting Forge World and now stood ready to defend it against the closing Alpha Legion and Iron Warriors. Finally, Mezoa mustered its own defence forces in the figure of the Mezoan Taghmata, battle-automata of diverse classes and models, all veterans of centuries of xenos raids before the eradication of the Mitu Conglomerate. In total, it has been estimated that the defenders of Mezoa numbered close to 12,000 men-under-arms, including the cybernetic monsters, towering Battle-Automata and soul-shorn Adsecularis Auxilia of the Taghmata Mezoa and several dozen Knights of House Hermetika.

Onto the Crucible of War

For historians, most of the great battles of the Horus Heresy are difficult to reconstitute -- too much data has been lost in the fires of that conflict or through the slow erosion of time. Even more has been sequestered purposefully by the authority of the Holy Ordos of the Inquisition or following the Edicts of the High Lords of Terra. It is fortunate that this is not the case for the Third Siege of Mezoa. Of these sources, the greatest wealth of information comes from the war chronicles of Nârik Dreygur, the de facto commander of the Iron Warriors' 114th Grand Battalion.

Although numbering in the thousands, the first wave of enemy dropships essentially carried pact-conscripts from Moab and other Imperialis Auxilia troopers who had declared for the Warmaster. Both were considered inherently expendable by their Legiones Astartes overlords, especially Autilon Skorr who commanded the Traitor armada. No defence cannons or flights of slaved Mechanicum drone-interceptors met the incoming assault wave -- Mezoa's guns remained eerily silent as the Magi had decided to turn to far more dangerous weapons: the wrath of Mezoa itself. Set deep beneath the stable crust of Mezoa's outer mantle, great subduction furnaces were used to hurl vast projectiles of magma and bedrock into the skies, each projectile easily measuring a kilometre in length. Against this weapon, the Traitor gunships and dropcraft stood no chance and the casualties proved devastating. Those few dropships that did manage to safely land on the ash-covered surface were eagerly awaited by packs of vicious Vorax-class Battle-Automata. Their Power Blades massacred the isolated Traitors and chased the scattered survivors into the caves and sulphurous crevasses of Mezoa's mantle where they would slowly choke to death, brought low by the heat, ash and toxic gases released by Mezoa's intense volcanic activity. Of the Traitor invasion's first assault wave, none survived, but unfortunately for the Loyalists, its intent was never to establish a proper beachhead but to provoke just such an aggressive response.

Autilon Skorr, the Traitors' leader, had correctly assumed that the Mezoan Magi would not be able to constantly maintain the exotic bombardment that had annihilated the first assault wave. Unless they wanted to entirely destroy their world or dangerously compromise its tectonic stability, the barrage would have to relent at some point. The massacre of the Traitors' first assault wave had achieved just that. Loath to squander his own troops in the bloody affair that was a planetary drop, Skorr placed the 114th Grand Battalion at the heart of his second assault wave, supplemented by what battle-hardened mortal troops remained. Encountering only conventional anti-air fire, the second assault wave suffered only minimal losses until it reached the volcanic, ash-shrouded surface of the defiant Forge World. Amid the scarred corpses and burnt-out wrecks of the first wave, a message reached Dreygur and his grim, iron-clad veterans. It was a message from Autilon Skorr informing them that each vessel trying to leave the surface in retreat would be shot down by the Alpha Legion's guns.

Now with no other option save victory, the Iron Warriors and their auxiliaries dug-in, transforming their drop-ships into makeshift bastions which would anchor their defence lines. Soon, the Loyalists rushed in, ready to chase the Traitors off their world. Under a hellish glow produced by the great magma-geysers that illuminated the battlefields, the Iron Warriors fought with a ferocity unmatched, save perhaps by those Legionaries that followed the bloody path of the XII Legion. Each Iron Warrior that fell killed at least three attackers in return, the 114th Grand Battalion demanding a steep price for every Terran inch of ground captured by the Loyalists. At the battle's climax, Nârik Dreygur faced the commander of the Loyalist detachment, the Imperial Fists swordsman and Champion Valtus Moran, and slew him, his cortex-controlled Battle-Automata tearing Moran's corpse to shreds, leaving the Loyalists to quit the field. At the end of the first solar day, the sacrifices of the Iron Warriors had secured a landing zone for the Traitor armada.

Soon the ash-plains at the edge of the great forge-fanes of Mezoa were swarming with activity. Sokar Pattern Stormbirds, amongst the heaviest vessels that were able to safely land on Mezoa's fragile surface, formed great bastions of overlapping Void Shields, their combined power great enough to repel the ground-shaking impacts of lava-coated bedrock flung against them. Soon both sides were firmly entrenched and facing each other over a short span of no-man's land. Using their superior numbers, the Traitors tried to push the attack home, their artillery trains targeting the forge-fanes' fortifications, creating breaches where Autilon Skorr mercilessly ordered his massed mortal auxilia to attack. Wherever the strength of the enemy seemed too much for mortal or Mechanicum soldiers to overcome, Skorr dispatched the 114th Grand Battalion, keeping his own Alpha Legion Astartes in reserve, shielding them from attrition wherever he could. While the Iron Warriors suffered mounting casualties, the Alpha Legion used the distraction caused by their allies to act as headhunters and raiders, targeting isolated Loyalist command units or sensitive installations and retreating to their lines before a counterattack could be mounted.

This did not mean that the Loyalists were content to sit idle while Skorr prosecuted his assault. The defence of the walls and fortifications fell to Mezoa's own Taghmata-forces and the heavy infantry of the Lethe Solar Auxilia Cohorts, thus freeing the Legiones Astartes contingent for more dangerous tasks. Reinforced by the remaining elements of the Imperial Fists, Xiaphas Jurr split his Disciples of the Flames into demi-companies of about 50 Astartes. These detachments conducted a series of spoiling attacks and lightning raids intended to disrupt the enemy's efforts. The Mezoan Magi supported these limited forays into enemy-held territory, isolating enemy troop concentrations by letting entire regions of the ash-plains collapse, burying the Traitors under a tidal wave of fiery lava or collapsing the enemy trenches upon them. The disorganised and isolated pockets of resistance were then cleansed by the Loyalist Astartes. Elsewhere on the battlefield, the Tech-adepts resolved to use suicide cohorts of Adsecularis Auxilia or Battle-Automata to lure the enemy into pre-planned kill-zones where great blasts of magma would annihilate friend and foe alike.

As with all things, the Mechanicum Adepts of Mezoa kept detailed records of their expenditures during the battle. Traitor and Loyalist casualties were compiled and run through mathematical simulations that would determine the Forge World's best response to the ever-changing tactical situation. Despite the small victories and the Loyalists' mastery of the terrain, the cold arithmetic of war did not favour Mezoa.

The Last Battle

For nine long solar days, Autilon Skorr led the Traitor host in an unrelenting siege of Mezoa's great forge-fanes and their spired halls. In high orbit, the Mangonel-class Bombardment Cruisers rained down clusters of kinetic munition to which the Mezoan Tech-adepts responded by hurling the white-hot burning blood of Mezoa itself into space. Entire chunks of the planet's mantle were blown into lower orbit, causing small, artificially-created meteor showers to rain down on the tortured landscape beneath. Venting scalding clouds of ash and steam, the rage of Mezoa's lifeblood cleansed entire battlefields of Traitors while fresh tides of magma buried armoured columns beneath them, consigning them to a fiery grave. To those that followed Autilon Skorr it must have seemed as if they had penetrated a living rendition of the mythological hell of Old Terra.

Safely entrenched behind the armoured walls of Mezoa's principal forge-fane, Xiaphas Jurr contemplated the battlefield and bore witness to the slow erosion of the Forge World's outer defences. Isolated as they were by the expansion of Horus' shadow empire, hopes of Loyalist reinforcements reaching Mezoa were nonexistent. In truth there remained little hope at all. Cassian Dracos, the true leader of the Disciples of the Flame, had yet to resurface from his isolation. Despite the losses inflicted to the Warmaster's lackeys, the enemy still heavily outnumbered the Mezoan defenders. Regardless of the inescapable logic of their defeat, the Loyalists of Mezoa had no intention of surrendering. The Norn-regents had decreed that Mezoa would not bow to the invaders and that as long as a single Battle-Automata still functioned, the Third Siege of Mezoa would not end. The Astartes, especially those of the Salamanders, were paragons of stoicism, determined to bleed the enemy for every inch of ground they took. With this grim resolve in their hearts, the Loyalists met each Traitor assault with stubborn resistance. While defeat might be inevitable, Jurr and the others like him would ensure that Horus' armies were denied a swift or effortless victory. The defenders' tenacity did not pass unnoticed and is said to have angered Autilon Skorr, like all ambitious military leaders under the Warmaster's banner, Skorr yearned to fight at the forefront of Horus' dark crusade and eventually stand beside him for the climactic Battle of Terra. To tarry here on Mezoa would only serve to incite the Warmaster's displeasure and see Skorr relegated to less glorious battlefields. Thus, Autilon Skorr could not afford to sit idle: Mezoa had to fall, and it had to fall quickly. In order to ensure victory, Skorr began plotting a single, decisive attack that would seal the defenders' fate and secure him a return to the favour of both the Warmaster and his own inscrutable gene-sire.

What remained of the 114th Grand Battalion of the IV Legion was committed en masse to a frontal assault on one of Mezoa's walls, a key defence bastion designated as Tertial-05 which protected the approach to the main forge spires. Despite the formal protest of the Iron Warriors' Consul Praevian, Nârik Dreygur, the attack was launched according to Skorr's plan, though the Iron Warriors only agreed to this on the assurance that Skorr and the Alpha Legion would support the attack. With the characteristic violence of a IV Legion assault, the Iron Warriors struck the defences at Tertial-05 like a hammer blow, wave after wave of gun-metal grey armoured Legiones Astartes advancing into heavy fire, heedless to the losses the Loyalists inflicted on them. Dreygur's attack quickly drew in defenders from other sectors of the walls, as even Tertial-05's mighty defences were unable to stop the advance of the 114th Grand Battalion. However, with steady reinforcements, the Loyalists stopped the retreat and slowly brought the Iron Warriors to a halt. Bogged down in the outer defences of Tertial-05, surrounded by Loyalist units and caught in a murderous crossfire, Dreygur ordered his men to dig in and set up makeshift defences within the captured positions they now occupied. Wherever the Loyalists threatened to break through, Dreygur sent his cohorts of Battle-Automata. As the Traitor casualties began to rise, Dreygur sent a pre-determined Vox-signal, later retrieved and deciphered by the Mezoan Magi, to the Alpha Legion, calling them to launch the second assault. But the Traitor Vox-network remained eerily silent.

Uncaring of the Iron Warriors' fate, Autilon Skorr and his elite Legion headhunter cohorts were already conducting their own assault on the Mezoan forge. With the majority of the defenders, and all of its Legionaries drawn away to engage the Iron Warriors, and his own forces still relatively fresh, Skorr and the Alpha Legion infiltrators only encountered depleted Battle-Automata maniples which they quickly overwhelmed. Soon, the infiltrators were nearing the main spindle-spires of the forge, where in the central chambers resided the Norn-regents themselves. Only the regents' own bodyguard now stood between Skorr and his main objective, a few dozen Domitar-class Battle-Automata. While each was a fearsome engine of war and one of the finest creations of the Mezoan Mechanicum, they could not hold out for long against the skill and sheer numbers of the Traitor Marines they now faced.

Fortunately for the defenders, Mezoa's central halls also harboured a fifty-Astartes-strong Honour Guard of the Disciples of the Flames. These Space Marines awaited the return of their lord, Cassian Dracos, who was still sealed within the forge-fane's inner sanctum. They had received strict orders from Dracos to guard the vaults, sparing no Legionaries for the battle raging but a short distance away. Led by the former Raven Guard Veteran Aleckto Kirhane, some Disciples chose to disobey their orders and joined the defence of the Norn-regents. With these unexpected reinforcments, the Domitar-class Battle-Automata and Space Marines were able to hold the line at the great spoked portals leading to the chambers of the Norn-queens, enabling a horde of multi-limbed Servitors to evacuate Mezoa's supreme rulers. Despite their heroic efforts, Autilon Skorr and his personal guard were able to penetrate the hall. With Lascutters and Meltaguns they set about hacking the sole remaining Norn-regent free of the intricate neural webwork linking her to Mezoa's defences. Once she was cut free, Skorr executed her. With the death of one of the ancient Tech-magi, utter chaos erupted amongst the mechanical defenders of Mezoa. All across the battlefield, Battle-Automata either collapsed or entered a stage of berserk and fratricidal fury, tearing each other or the enemy apart. Sentient units like the Skitarii or Thallax cohorts found themselves cut off from all external direction, focusing on the fight at hand. Sensing the defenders' distress, Traitor units surged forward to attack all across the warzone. Only at Tertial-05, where the Lethe Solar Auxilia and the Disciples of the Flames kept the Iron Warriors pinned down in a murderous crossfire was the enemy kept in check. It seemed that the end had finally arrived.

The Draconis Revenant Returns

It was at this moment that the doors to the inner vaults opened and Cassian Dracos emerged from his seclusion in the fabrication vaults, his ancient Dreadnought chassis restored to its former glory by the arts of the Mezoan forge wrights. Yet rather than lend his strength against Autilon Skorr and his Alpha Legion warriors ransacking the central spires of Mezoa, Dracos led his Honour Guard towards Tertial-05 and the Iron Warriors. As the Dreadnought charged forth, those automata he passed shook off whatever feedback-induced mania had befallen their cortex and gathered around the Iron Dragon, now slaved to Dracos' indomitable will. By the time Dracos reached the shell-scarred battlefield of Tertial-05 it was at the head of nearly a thousand Battle-Automata. Yet rather than leading a decisive charge against the remaining Iron Warriors, now entrenched in a formidable makeshift fortress of broken rockcrete and iron, Dracos approached alone, calling upon the enemy commander to show himself. Heedless of any danger, Dracos passed through the ranks of the Iron Warriors' own Battle-Automata, the robots refusing to follow Dreygur's orders to engage the Dreadnought. While Nârik Dreygur stood tall upon the fortifications his brothers had built, Dracos remained below. What words the two leaders exchanged remain largely unknown, but The Prophecies of the Flames records that, "Wheresoever is found the craft of the forge, the avatar of our lord Vulkan has power, even in the flesh of the enemy where it has felt the touch of the forge. So he turned the foe to the cause of righteousness."

Even the private journals of Consul Praevan Dreygur do not mention this incident. In truth, after that day he made no more private recordings and eschewed all company save that of Dracos and his automata. What is known is that as the two met, they exchanged few words and Dreygur turned to address his men: "Brothers, once more an oath to us stands broken. The Alpha Legion has abandoned us once again. Now we shall show that we do not renege on our vows. The dead of Stranivar and Mezoa both call for vengeance, and we shall grant it to them."

Ancient Nehalen Contempt Dred

The Alpha LegionContemptor Pattern Dreadnought, Ancient Nehalen, who was vanquished in personal combat by Cassian Vaughn

Almost silently, the Iron Warriors of the 114th Grand Batallion reloaded their Bolters and followed the towering form of Ancient Orgol, a Deredeo Pattern Dreadnought, towards Mezoa's central spires where their quarry lurked. Still believing victory lay within his grasp, the dark blood and oil mix of the slain Norn-regent wet on his master-crafted Power Axe, Autilon Skorr remained blissfully unaware of the Iron Warriors' change of allegiance, He soon discovered that he was trapped at the heart of the resisting forge-fane. Slowly but steadily, the two remaining Norn-queens wrestled back control over their cohorts of Battle-Automata as a solid wall of Legiones Astartes Power Armour rushed across the open ground, those vengeful survivors of the 114th Grand Battalion at their head. Soon, Skorr's vox-bead was alive with the panicked news that armoured columns of Solar Auxilia were attacking his landing zones, while in orbit the Loyalist vessels had emerged from their hiding places and were now attacking the dispersed Traitor fleet. Focused on bombarding the Forge World below, Skorr's warships were not expecting such a sudden assault, and their losses would likely be severe. Knowing his daring gamble had failed, Autilon Skorr hefted his weapons and ordered his men to fight through the onrushing Loyalists. His personal bodyguard and herald, Ancient Nehalen, led the assault. Skorr and his men would eventually break through, the Contemptor Pattern Dreadnought Nehalen locked in deadly combat with Cassian Dracos himself, whilst Skorr was badly wounded by a hit of Xiaphas Jurr's powerful Crozius. With their forces in disarray and their leader wounded, the Traitors soon abandoned the surface and retreated to their voidships. The Third Siege of Mezoa was over.


Although the enemy troops still numbered in their thousands, the remaining Cohorts of the M'Pandex Taghmata, now leaderless, were crushed in a matter of solar hours. The first to abandon their allies and flee the surface of Mezoa were the forces belonging to the 78th Chapter of the Alpha Legion, a fact that permitted them to escape with the least casualties. While the Traitors initially succeeded in maintaining orbital superiority, high-speed passes and raids by Loyalist vessels such as the Ebon Drake and a new salvo of projectiles torn from Mezoa's fiery heart soon forced the Traitor fleet to retreat to the outer system and eventually leave Mezoan space entirely.

Though unconquered and still defiant, the damage dealt to Mezoa's infrastructure by the Traitor assault was great. The forge-fanes were so damaged that it would take the Tech-adepts many standard years to reconstitute their former strength and for the Mezoan Taghmata and House Hermetika to recover from their losses. Furthermore, the death of one of the Norn-regents caused much strife within the Mezoan Tech-priesthood as the different orders within the forge struggled to fill the void left by her death. Cassian Dracos' status was also an enigma: while some lauded him as the saviour of Mezoa, others mistrusted him because of the strange orders he gave during the siege and the unnatural authority and influence he had displayed over the creations of the Mechanicum. Still determined to take the fight to the Traitors, Cassian Dracos led numerous raids into Traitor-held territory, actions which only served to cement his reputation and fuel the cult of personality that sprang up around him. The result was a gradual increase in the numbers of the Disciples of the Flames. While the leader of the 114th Grand Battalion, Nârik Dreygur became a close confident to the Iron Dragon -- rarely to be seen without his new master -- many records indicate that several Iron Warriors, most of them vocal opponents of Dreygur, mysteriously vanished after the Loyalist victory, although neither Dreygur himself, nor Dracos officially ordered the ranks of the 114th to be purged.

While Mezoa was unable to reach out to other beleaguered Loyalist star systems, the defiant Forge World remained a thorn in the Warmaster Horus' side for the duration of the Heresy. With the Traitor blockade broken, its precious vessels needed for the Warmaster's drive on the Segmentum Solar, Mezoa became a safe haven for those who had successfully escaped or avoided the clutches of the Sons of Horus and their traitorous allies. Several independent companies of Legiones Astartes, the most prominent of them the Disciples of the Flames, used Mezoa as a base for their own war of vengeance upon the Traitors from behind the enemy's lines. While limited in scope, it was the actions of these isolated Loyalist companies and others that would buy the Imperium valuable time to reinforce its defences and prepare for the Traitors' attack upon the heart of the Emperor's realm.


  • The Horus Heresy - Book Six: Retribution (Forge World Series) by Alan Bligh, pp. 33-53

Battles of the Horus Heresy
005-006.M31 Istvaan III AtrocityBurning of ProsperoWar Within the WebwayBattle of the Somnus CitadelUnrest on CalibanSignus CampaignSchism of MarsBattle of DiamatDrop Site MassacreFirst Battle of ParamarBattle of the Coronid Deeps
007-008.M31 Battle of PhallBattle of RavendelveBattle of the Alaxxes NebulaSiege of the Perfect FortressChondax CampaignSecond Battle of ProsperoFirst Siege of Hydra CordatusBattle of the Furious AbyssBattle of CalthBattle of ArmaturaShadow CrusadePercepton CampaignBattle of IydrisThramas CrusadeFall of Baztel IIIBattle of VannaheimSecond Battle of ParamarBattle of Constanix IISiege of Epsilon-Stranivar IXTreachery at Port MawManachean WarMezoan CampaignBattle of BodtBattle of DwellBattle of Molech
009-010.M31 Xana IncursionCarnage of MoroxSangraal CampaignLiberation of NuminalBattle of ArissakBattle of PerditusBattle of SothaScouring of Gilden's StarBattle of NyrconBattle of TallarnBattle of NocturneSolar WarBattle of Pluto
011-014.M31 Malagant ConflictBattle of the Kalium GateBattle of CatallusBattle of TralsakTarren SuppressionBalthor Sigma InterventionScouring of the Ollanz ClusterBattle of ZepathBattle 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-GarmonBattle of TerraGreat Scouring
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