The Fall of Prospero, also referred to as the Scouring of Prospero, the Burning of Prospero and the Battle of Prospero, was the name given by later Imperial scholars to the sanctioned Imperial military reprisal against the Thousand Sons Legion of Space Marines' homeworld of Prospero at the start of the Horus Heresy in the early 31st Millennium.
The action was carried out by the Space Wolves Legion and elements of the Legio Custodes and the Sisters of Silence as a punishment for the Thousand Sons' flagrant violation of the Emperor of Mankind's edicts against the use of psychic powers and sorcery made at the Council of Nikaea.
The Sorcerers of Prospero
Magnus the Red, Primarch of the Thousand Sons, was the most powerful psyker of all the Primarchs, the genetically-engineered superhuman sons of the Emperor of Mankind who led the Legions of the Space Marines. After being transported as an infant by the Ruinous Powers through the Warp from the Emperor's gene-laboratories beneath the Himalayan Mountains on Terra, Magnus' gestation-capsule came to rest far across the galaxy on the Civilised World of Prospero. This unusual human world embraced the psychic mutations amongst its population rather than seeing psykers as dangerous witches and Renegades who had to be slain or exiled as was the norm on most human worlds before the Imperium annexed them during the Great Crusade. Psykers born on Prospero were not outcast by their fellow Prosperines but were instead embraced as their world's natural leaders because of their abilities. When the newborn Primarch was found in his gestation-capsule that had fallen from the heavens, he became a ward of the psychic scholars and leaders of Prospero, and soon displayed the same powers, though his psychic strength was beyond anything that had ever been seen by the Sorcerers of Prospero. Magnus' abilities soon surpassed those of his primary tutor in the psychic arts and he was recognised as the world’s preeminent sorcerer and the leader of the ruling Commune of Prospero. Elevated as the rightful leader of Prospero, he unified its sometimes squabbling Cults of Sorcerers and set towards transforming Prospero into a centre for knowledge and the arts of sorcery drawn from across the galaxy.
When the Emperor of Mankind was finally reunited with his lost son after the Great Crusade reached Prospero and incorporated it and its people into the Imperium, he cautioned Magnus about the dangers inherent in the practice of psychic sorcery and the nature of the Warp. The Emperor knew that Magnus was a very powerful psyker and possessed an unquenchable thirst for knowledge. He believed that it was dangerous for his son to remain ignorant of the secrets of the Immaterium and the ancient, dark intelligences that resided there, and so the Emperor showed Magnus the truth of the Warp. Feigning shock and horror at the Emperor's revelations, Magnus agreed to renounce sorcery and to lead his people away from the study of the occult, but he secretly dismissed his father's warnings. For Magnus had already peered into the Warp and had become obsessed with the potential promise of psychic power.
Sorcery of the Thousand Sons
After the Emperor arrived on Prospero, Magnus was reunited with his genetic progeny amongst the XV Legion of the Space Marines. The XV Legion had been formally named the Thousand Sons by the Emperor and given their own Expeditionary Fleet so that they might begin to make contributions to the Great Crusade the Emperor had unleashed upon the galaxy to reunify all of Mankind beneath the aegis of the Imperium of Man. Like their gene-father, the Thousand Sons had inherited powerful psychic talents, as their gene-seed organs possessed their Primarch's own psychically-potent genes. However, the Legion's gene-seed was also genetically unstable, and often produced unwanted mutations known as the "Flesh-Change" by the Legionaries. The Flesh-Change was much feared amongst the Thousand Sons, as the spiral of degenerative mutation ultimately reduced a proud Thousand Sons Astartes into a mindless mutant abomination similar to a Chaos Spawn. The majority of those Thousand Sons afflicted by the Flesh-Change were put into stasis by the Legion in the hope that someday in the future a cure would be found that could reverse the onset of these crippling mutations. The number of active Astartes within the XV Legion soon began to dwindle to dangerously low levels as a result of the ravages of constant mutation. Some within the Imperium called upon the Emperor to declare the Legion hopelessly corrupted and remove them from the Great Crusade's active order of battle.
By the time the Thousand Sons were reunited with their Primarch Magnus, they numbered only one thousand active Astartes -- literally the "thousand sons" of Magnus. Through unknown means after his restoration to his Astartes, Magnus gained the knowledge required to cure his Legion's tendency towards rampant mutation. He even restored his sons who had been afflicted with the Flesh-Change and placed in stasis, making the XV Legion whole once again. The Legion quickly adopted Prospero as its new homeworld and many of Magnus' followers from amongst the Sorcerer Cults on the planet were recruited into the Legion's ranks. Despite the Emperor's earlier warnings, the Primarch continued to obsess over the acquisition of the forbidden knowledge of the Warp and never ceased to practice sorcery. Magnus secretly taught the Thousand Sons the ways of the Sorcerers of Prospero, and to embrace their psychic talents as a gift rather than suffer them as a curse. Within a short period of time the Thousand Sons had become a secret cabal of powerful Warp sorcerers.
Throughout the era of the Great Crusade, the psychic talents of the Thousand Sons proved useful innumerable times as the XV Legion fought bravely in multiple campaigns, leaving few in doubt of their achievements. However, there were those Primarchs such as Leman Russ of the Space Wolves, Mortarion of the Death Guard and Corax of the Raven Guard who could never bring themselves to fully trust Magnus and his Thousand Sons because of their own strong feelings against the use of sorcery and psykers in general. Leman Russ, the product of a feral barbarian culture on the Death World of Fenris where all psykers were feared as fell witches, condemned the Thousand Sons as warlocks who employed fell magicks. Mortarion openly accused Magnus of dabbling in foul sorcery, and Corax twice refused to field his Legion alongside the Thousand Sons.
Space Marine Librarians
Unlike his brother Primarchs, Magnus the Red saw the potential in exploiting the powers of psychically talented Astartes and was instrumental in the development of the Space Marines' corps of Librarians. In some of the Astartes Legions the psychic mutation was relatively common, and it was felt by some of the Primarchs that such individuals should be allowed to continue to use their innate psychic abilities for the benefit of the Legion. This would allow these gifted Battle-Brothers to be of use to their Legion without presenting any danger to their fellows or to the civilians of the Imperium. Magnus and a number of other Primarchs created a program for the training and development of psyker Astartes that supplemented the traditional process for creating a new Space Marine. The Emperor was asked to approve of the recruitment of these psykers into the ranks of those Legions who wished to make use of them, and he sanctioned these first experiments as a means of controlling the spontaneous outbreaks of psychic mutation within the ranks of the Legions. The Librarians quickly proved to be loyal and effective warriors and soon gained the Emperor's and the Primarchs' acceptance of their presence on the battlefield, rapidly becoming a powerful addition to the ranks of the Space Marine Legions.
However, there were those Primarchs who raised their voices in dissent, arguing amongst themselves and with the Emperor that Librarians should not be permitted within the ranks of the Astartes. Some desired to expand their Legions' Librarius and recruit even more Librarians into their ranks, whilst other Primarchs vehemently opposed the entire notion of Librarians and felt that they should be expunged from their ranks altogether. Primarchs such as Leman Russ felt that Librarians were no better than witches. Corax and Rogal Dorn also refused to commit their Legions to fight alongside other Legions that made use of Librarians. Mortarion in particular accused his brother Magnus of using the forbidden arts of sorcery.
Dismayed at the accusations leveled against Magnus and the friction the issue was causing amongst his Primarchs, the Emperor was also concerned about the Librarians and the dangers they presented to the Great Crusade when he was no longer fighting directly alongside his Space Marine Legions. Before departing for Terra to begin his secret Imperial Webway Project within the seclusion of the Imperial Palace's dungeons, he summoned the Primarchs and all the other major Imperial leaders to a War Council summit on the world of Nikaea to address the Librarian crisis.
Council of Nikaea
To end this growing dispute over the use of psychic abilities once and for all, the Emperor summoned the Imperial War Council to the newly terraformed Frontier World of Nikaea to resolve the issue over the use of psychic powers in the Imperium of Man and so that Magnus could rebut the charges of sorcery that had been laid against him. This great conclave, later known to Imperial savants as the Council of Nikaea, consisted of the Primarchs as well as Imperial officials drawn from all the various Adepta of the Imperium. From his throne upon a high dais, the Emperor presided over the proceedings on Nikaea in an ancient amphitheatre as each side in the debate made their presentations to him. The Primarch Mortarion repeated his charge that Magnus employed the use of sorcery whilst Magnus defended his actions and extolled the great deeds achieved by the Librarians and his own Legion's psykers. He also pointed out that the Imperium was already completely reliant on the use of psykers such as Astropaths and Navigators for interstellar communication and transportation as evidence to help his cause.
The Council of Nikaea was also the trial of Magnus the Red -- for he was accused of sorcery and of introducing sorcerous practices to the Space Marine Legions through the institution of the corps of Librarians. As the evidence of Magnus' continued practice of sorcery became apparent, the Emperor barely contained his wrath as he pronounced judgement on the Primarch of the Thousand Sons, for he had entrusted his son years before to obey his bidding and foreswear the use of such occult practices because of the dangers inherent to the Warp. He had entrusted only Magnus with the true secrets of the Warp to which only they remained privy, but now it appeared that his son had disobeyed his edicts and at the very least dabbled in the occult and the forbidden black arts of psychic sorcery.
The Emperor's judgement at the Council of Nikaea proved severe. With the exceptions of Navigators and Astropaths who were properly trained, controlled and sanctioned by the Imperium and were necessary to its continued existence, the Space Marine Legions were no longer to employ psykers within their ranks. The Emperor commanded that the Primarchs were to close their Librarius departments forthwith and not to indulge the undoubted psychic talents of those Asartes who possessed the gift. All existing Space Marine Librarians were likewise forbidden to make use of their abilities. The Council's rulings also created a new position amongst the Space Marine Legions, the Space Marine Chaplain, to uphold the Imperial Truth and help maintain the purity of an Astartes Legion's dedication and fidelity to the Emperor's commands.
Furthermore, Magnus was ordered to return to Prospero to reorganise his Legion, disband the Legion’s Librarius and redeploy its existing large corps of Librarians to the Legion's Battle Companies. The Emperor censured his use of psychics and dismissed Magnus with a final threat -- a fate that had also befallen the Lost Primarchs of the II and XI Legions: "If you treat with the Warp, Magnus, I shall visit destruction upon you. And your Legion's name will be struck from the Imperial records for all time."
Retreat to Prospero
Bitterly disappointed by the outcome of the Council of Nikaea, Magnus secretly raged against the Emperor and what he saw as his father's unjust ruling. The Emperor had made his feelings crystal clear: Magnus was to cease all use of sorcery and psychic powers on pain of death. The Emperor had censured Magnus publicly for such activity and had warned him in no uncertain terms that he would be destroyed if he were to disobey the Edicts of Nikaea. Yet Magnus had no intention of giving up the promised power and knowledge of the Warp and continued to study the Immaterium and its secrets. He met with his senior Librarians and persuaded them to collude with his plan to secretly continue their studies of the occult and sorcery.
Following the Council of Nikaea, a recall order was astropathically transmitted to all of the Legion's far-flung Expeditionary Fleets, with the bulk of the Legion's number present on Prospero just before the Fall of Prospero. However, some of the Thousand Sons' Astartes had not arrived on Prospero when that world was assaulted. This would include those elements of the Thousand Sons such as Captain Menes Kalliston and his 4th Fellowship. The fate of these Thousand Sons Astartes untainted by their Legion's fall to Chaos remains unrecorded -- or deliberately excised -- from Imperial records.
A Vision of Betrayal
The Warmaster Horus was being treated for the mortal wound he had sustained fighting alongside his Luna Wolves Legion against the Renegade Imperial Planetary Governor Eugen Temba on the Feral World of Davin within the Temple of the Serpent Lodge. Unbeknownst to anyone else in his Legion, the Warmaster's healing had been prearranged by First Chaplain Erebus of the Word Bearers so that the Chaos Cultists of the Serpent Lodge could transport Horus' soul into the Warp where he was seduced by the Ruinous Powers into betraying and challenging the Emperor for control of the galaxy. Magnus, meditating on Prospero, peered into the Warp with his one good eye and foresaw the pact with Chaos that the dying Warmaster had made to save his life. He also foresaw the epic events that were yet to unfold in the galaxy and could prove dire to the survival of the Imperium -- Horus' betrayal, the deaths of some of his Primarch brothers and the actions of those who would betray their oaths to the Emperor. The only fate the vision did not reveal was Magnus' own.
Burdened with the terrible information provided by this precognitive vision, Magnus gathered about him the secret cabal of his Legion's Sorcerer Librarians to discuss and interpret the meaning and implications of these dire portents. After much deliberation they resolved to break the proscriptions of the Edicts of Nikaea and psychically contact the Emperor on Terra to warn him of Horus' impending betrayal. Magnus used the power of his Legion's greatest sorcerers to convey the news of the impending civil war to the Emperor himself on Terra via a sorcerous spell, rather than use the legal but unreliable means of astrotelepathy.
Troubled by the revelations of Horus' betrayal and the coming galactic civil war, Magnus risked further censure from his father by employing the use of a daemonic spell to warn the Emperor. Why Magnus chose to warn his father in this fashion is not clear, for surely he knew the Emperor would recognise the taint of Chaos on this forbidden sorcery. Nevertheless, the cabal of Thousand Sons Sorcerers joined their Primarch to cast this mighty spell, projecting the potent conjuration towards Terra through time and space. Magnus' spell breached the protective wards and hexes around the Imperial Palace and penetrated the subterranean levels of the Palace's dungeon deep within the earth. The spell lanced directly into the Emperor's brain, instantaneously filling him with the knowledge of the dark precognitive vision of Magnus and of the details of Horus' corruption by the Dark Gods. The spell also disrupted the wards surrounding the Emperor's secret construction of a new extension into the Webway from Terra and led to the deaths of hundreds of Adeptus Mechanicus Tech-priests and Servitors who were suddenly exposed to the perils of the Warp.
The Emperor's Wrath
- "They are sorely misguided if they think the Warp has the power to overcome my Will. My vengeance shall haunt them across all of time and they shall never know peace. They have earned themselves only eternal damnation."
- — The Emperor’s promise after the destruction of His Imperial Webway Project
Magnus' daemonic conjuration of unprecedented power had breached the psychic defences of the Imperial Palace on Terra. Magnus felt that this was to be his moment of triumph and vindication as only through the power of sorcery had Horus' betrayal been revealed. He believed that his father would at long last see the value of its use. But instead of vindication, Magnus received nothing but wrath. The Emperor was not pleased with his son's warnings or the disruption to his precious Webway Project, and flew into a terrible rage that Magnus should dare to so flagrantly disobey his orders to renounce sorcery and psychic power. He was further enraged by Magnus' obvious deception in pretending to lay down his psychic powers, which he saw as evidence of the worst sort of oath-breaking. Completely ignoring the contents of Magnus' dire warning, which he believed to have been fabricated by the Ruinous Powers, the Emperor called forth the Primarch Leman Russ of the Space Wolves Legion, and commanded him to move on the world of Prospero and prosecute the rebel Primarch and his Legion. For consorting with the powers of the Warp in direct contradiction of Imperial edicts, they were to be shown no mercy.
The Wolf King brought the entire VI Legion to sanction Prospero -- an entire Astartes Legion to punish another entire Legion. The fleet's components assembled at the world of Thardia and then translated through the Warp to three further assembly points, gathering strength as they went. Amongst the Space Wolves' forces were a contingent of Legio Custodes, bequeathed by the Emperor himself to strengthen their cause. Accompanying Russ was also a fleet of Black Ships, with orders to carry back to Terra any psykers or sorcerers left on the planet after the Thousand Sons had been dealt with.
The Space Wolves were also aided by the Silent Sisterhood. Untouchables who carried the Pariah Gene, the Silent Sisters were psychic blanks who were immune to psychic assaults and whose very presence was anathema to the likes of the Sorcerers of Prospero. The Space Wolves and the Custodians were tasked with defeating Magnus' Legion on the field of battle, and arresting the malcontent Primarch. The Sisters of Silence were to apprehend and detain any and all surviving psykers for transportation to Terra on the Black Ships accompanying the fleet where they were to be judged and have due sentence served upon them.
The prospect of prosecuting the Emperor's decree was a difficult one, for the Space Wolves understood that even without their sorcery, the Thousand Sons were still Astartes. That fact alone put them in a different class from most opponents. Moreover, Prospero was their Legion homeworld. A Legion was always strongest at its base of operations. But the sanction of the Thousand Sons would be executed, regardless of the cost.
Magnus had finally understood, after his forced psychic entry into the Hall of the Golden Throne and his direct mental communication with the Emperor, that he had been manipulated by Tzeentch, with whom he had apparently unknowingly consorted while desperately looking for a way to stop the emergence of the psychic mutations that were threatening to destroy his Legion. In an act of repentance and sacrifice, and to show his father that he and his Legion were loyal to the end, he did not warn the defenders of the planet or his Legion of the coming Imperial attack: on the contrary, he imposed a psychic veil on the planet so the Thousand Sons would have no clue of the impending assault. He also dispersed the Thousand Sons' Legion fleet far away from Prospero. He knew that Tzeentch wanted the Thousand Sons and Space Wolves to slaughter each other, and he wanted to stop these plans, even if it meant the sacrifice of his Legion and homeworld. Therefore, the Space Wolves' attack on the Thousand Sons' homeworld of Prospero came as a complete surprise to its people and the Astartes Legion who protected them.
Recovered records of the XV Legion show that no information regarding the Imperial Censure Fleet, or even of the Emperor's displeasure, was ever disseminated to the Legion. As the combined armada of Leman Russ and Constantin Valdor drew ever closer to the world of Prospero, the Thousand Sons busied themselves with mundane maintenance and their own esoteric training, oblivious to any threat. No attempt was made by the XV Legion or the various regiments of the Prosperine Spireguard to fortify any of the key defensive positions within the city of Tizca, the only large-scale urban settlement on Prospero to survive the Age of Strife. In several cases, there were even reported disappearances of key Legion and civilian personnel who appeared to have stumbled across information related to the fleet's approach and then were silenced, with the evidence at hand suggesting the use of potent memory-altering telepathy to quell any unrest at the sudden disappearances, a feat few even a Legion such as the Thousand Sons were capable of.
The Scouring of Prospero
Thunder from Fenris
As the Imperial sanction fleet translated from the Warp and burned in towards Prospero, it became evident that the planet had strangely not activated its planetary defences. The Prosperine defence grids were non-functional at every layer of security, from the outer orbital defence platforms to the close surface planetary defence cannons. Individual cities were still screened by active defensive measures, but that was standard Imperial operating procedure and not a response to an approaching threat. There were signs that civilian ships had fled or were fleeing the planet and the star system in considerable numbers. Some of the escaping vessels were overtaken and boarded by the Imperial fleet. Their crews and passengers were taken captive and interrogated by the Space Wolves' Rune Priests, so that every useful scrap of intelligence about the target could be gathered.
With no response from the ground, the Imperial armada moved into high orbital anchor above Prospero and assumed a geostationary assault pattern. Thousands of weapons were trained on the planet below: energy weapons, mass-drivers and kinetic bombardment cannons. The starships drifted sedately like grand liners in a regatta among the stars. Leman Russ' flagship, the Battle Barge Hrafnkel, opened the orbital assault, its massive weapons systems etching lines of icy light into the surface of Prospero. Moments later, the rest of the Imperial fleet opened fire.
The first bombs from the Space Wolves' fleet struck Prospero just before dawn. The Prosperine orbital defence platforms were caught completely unawares. One minute their Augurs had been silent, the next a vast fleet of ships had appeared, a buckshot spread of torpedoes already arcing towards the orbital batteries and missile defences. Most were knocked out before they were able to launch a single weapon or power up a single gun. The lucky few that managed to get off a quick snap shot were bracketed and obliterated moments later. Though Magnus had chosen to keep his Legion blind to the approach of the Emperor’s vengeance as he wished to display his own repentance for his actions, the telekinetic Sorcerers of the Legion's Raptora Cult maintained a constant psychic "Kine-Shield" over Prospero's capital city of Tizca. Not even Magnus the Red could undo that protection without someone noticing and wondering why.
The first warning anyone in Tizca had of the imminent Imperial attack was a hot wind that seemed to come straight from the sky, pressing down on the city like the pressure before a storm. It tasted of metal and burnt oil. Static leapt from the Tizcan pyramids’ tops, sparking from silver tower to silver tower. The grey, pre-dawn sky erupted in light as the lowered clouds were lit with an inner radiance. This was swiftly followed by the tremendous crash of atmospheric discharge, like thunder without the lightning. Multiple sonic booms from incoming hypersonic projectiles shattered the silence of the sleeping city, and those citizens of Tizca who still dreamed were shaken from their beds by the echoes as percussive blasts rolled across the urban landscape. Like a stabbing finger of raw light, the first energy lance from the orbiting Imperial fleet struck Prospero a kilometre northeast of Tizca.
The total saturation of the target area ensured that the Prosperine capital city was completely engulfed, enough to level a continent’s worth of metropolises. Yet Tizca endured. The telekinetic Kine-Shields of the Thousand Sons' Raptora Cult were the strongest defences any city in the Imperium could boast. Harder than the thickest Adamantium and more unyielding than layer upon layer of standard gravitic Void Shields, the invisible umbrella of telekinetic protection soaked up the violence of the bombardment, though at fearsome cost to the Astartes who maintained it.
Magnus the Red watched as the lightstorm blistered and burst over his beautiful city. The sky was stained a bloody orange as airbursting incendiary rounds burned the clouds away, and a tear fell from his eye as he watched the beautiful land around Tizca die. The forests were burned to ash and the wild grasslands blazed with secondary fires, reducing the unspoiled countryside to a wasteland in a matter of minutes. The Desolation of Prospero was complete. Now the Primarch knew how his father felt about his psychic intrusion into the Imperial Palace and his continued use of sorcery. He accepted his just punishment for his arrogance in flagrantly disobeying the Emperor's wise edicts.
Shortly after the orbital bombardment began, the Imperial invaders arrived by the thousands -- wave after wave of drop-ships, assault boats and gunships sped inbound to the planet's surface. Behind them came bulkier cargo transports bearing armoured vehicles and artillery pieces. The Kine-Shields of the Raptora Cult could not protect Tizca from the attack, but their cover was no longer needed. The bombardment from orbit had ceased, and squadrons of Stormbird gunships led the charge, skimming low over the water towards Tizca’s port. Hundreds of Imperial craft flew over the churning seas, leaving foaming breakers in their wake. The idea that any enemy could reach the surface of Prospero to launch an assault had been discounted, and as a consequence, there were no Prosperine antiaircraft batteries to meet the oncoming invaders. The route into Tizca was wide open.
The first gunship to land, an enormous Stormbird with steel-grey sides and the image of twin wolves painted on its blunt prow smashed into the eastern quarter of the capital that was known as Old Tizca, blasting its way in with a salvo of missiles and a blast of cannon fire. Landing skids deployed at the last second, and the aircraft came down hard in the wreckage. No sooner had it set down than the assault ramps dropped and Leman Russ himself set foot on Prospero, the first invader ever to do so. He roared to the skies, and the devastation wrought by his fleet above was pleasing to him. Two enormous Fenrisian Wolves howled at his sides, and a score of his most powerful Astartes fought their way into the port.
As the Space Wolves drew first blood, Prospero’s military responded. The citizen militias of Tizca rose in defence of their city, gathering what arms they could and taking up firing positions on rooftops and at windows. No one was fool enough to think they would be anything more than irritants to the Space Wolves, but to let the invaders simply walk into Tizca without a fight was as abhorrent as it was unthinkable.
The Skyguard Air Command launched every squadron of their two-man skimmers from their hangars to the south. These disc-like anti-gravitic aircraft were armed with Heat Lances and Missile Pods, and the sky above the city became a frantic mess of gunfire, streaking missiles, explosions and dogfights as the two forces dueled for supremacy.
The Imperial Army regiments of the Prosperine Spireguard attempted to bear the brunt of the Astartes' assault, meeting the barbarian warriors of the Space Wolves bravely but futilely on the field of battle. The Spireguard, already on high alert after the commencement of the orbital bombardment, moved out en masse under the guidance of the Thousand Sons’ Corvidae Cult. Ordered to defend Tizca, they did not falter from that order despite the overwhelming odds arrayed against them.
Elements of the 15th Prosperine Assault Infantry, under Captain Sokhem Vithara, occupied the upper slopes of Old Tizca, anchoring their defence between the fire-wreathed pyramid of the Pyrae Cult, the Skelmis Tholus, which lay a kilometre to the west of their position and the Corvidae Cult's own pyramid. Vithara set up his command post in the vestibule of the Kretis Gallery, the oldest repository of artwork and sculpture on Prospero.
In the southwest quadrant of the city, the Prospero Assault Pioneers rallied what little was left of their soldiers after the avalanches caused by the orbital shelling swallowed three of their barracks. The northern Palatine Guard deployed on the edges of the burning port, occupying high parapets that overlooked the libraries and art galleries of the Nephrate District. Their commander, Katon Aphea, was the heir apparent to one of Prospero’s oldest families, a young and gifted officer with great potential. He anchored his defence on the Caphiera Tholus and positioned his troops with a tactical acumen that would have been lauded at any of the Imperial Army's officer scholam.
Leman Russ and his Space Wolves overran Aphea’s position in less than two minutes. Tizca burned as dawn’s light crept over the horizon. Yet, though the Space Wolves had struck an overwhelming blow, they had yet to face the city’s true defenders. The Thousand Sons deployed, and suddenly the fight took on a very different character.
Brother Against Brother
Old Tizca was no more. The peaceful warren of antiquated streets was now ashes and burning rubble. Warriors picked careful paths through the smouldering ruins, firing from the hip or fighting with Chainaxes and Chainswords. The coastline was invisible, obscured by fog-banks of artillery fire. What had once been a wondrous beacon of illumination for all who cared to look upon it was now a maelstrom of battle. The northern spur of the city was a raging inferno, its palaces ablaze and its parklands ashen wastelands. Further south, the port was a giant black stain on the horizon, its structures demolished in the wake of the Space Wolves' attack.
Though the majority of the Spireguard had been swept away in the opening moments of the battle, the Thousand Sons rallied magnificently and prevented the battle from becoming a rout. A thin line of Astartes in crimson Power Armour linked the six pyramids of Tizca, forming a circular perimeter with Occullum Square at its centre. The Pyramid of Photep was the southernmost of the pyramids, the glittering water surrounding it awash with sodden pages of ancient wisdom lost forever in the name of fear.
The Thousand Sons were dying. Scores of them died in the opening minutes of the Wolf King’s attack, his fury unstoppable and his power immeasurable. Clad in the finest suit of Artificer Armour and armed with a Fenrisian Frostblade that clove warriors in two with single strokes, his fury was that of a pack hunter who knows his brothers are with him. His huscarls were grimly efficient butchers of men, their Terminator Armour proof against all but the luckiest shots and blade strikes.
Though the Thousand Sons' Sorcerer Librarians could not see the Sisters of Silence, they were still there, for the Librarians' psychic powers were weakening. The warriors of the Legio Custodes slew with powerful strokes of their Guardian Spears, hewing Ceramite and flesh alike with efficient killing strokes. The slaughter continued as the Space Wolves quickly thinned the ranks of the beleaguered Thousand Sons. The doom of the Thousand Sons would soon be upon them, for fewer than 1,500 Astartes of the Legion remained alive. Facing more than three times their number and the fury of a Primarch like Leman Russ, this was a battle that could only end one way.
Unable to oppose the brutality of the Space Wolves, the Thousand Sons finally relented, and unleashed their maleficarum, their black sorcery, upon their foes, but by doing so, they had inadvertently justified the Imperial sanction against them -- for they were now truly no better than Renegade warlocks and witches. Using their vile magicks, the Thousand Sons pushed backed the Space Wolves' assaults and slew a great number of the maddened warriors of Fenris. It seemed that the tide of the battle had turned, and that the Thousand Sons might yet salvage the day. But soon a new enemy opposed the Sorcerers of Prospero.
The Tide Turns
The Silent Sisterhood finally made their presence fully known as the Null Maidens poured down from the black heaps of burning rubble into the fight. They uttered no war cry or challenge as the blankness of their lack of presence in the Warp washed across the Thousand Sons' line. The rank clouds of maleficarum burned away, or blew aside like fog in a night wind. The Thousand Sons choked on the words of their conjurations, gagging upon the utterances of their spells. They staggered back, clutching at their throats, pawing at the neck seals of their helms, blood spurting and leaking through visor slits. Arcane gestures and motions ceased as their hands transformed into arthritic claws. Seconds after they had stunned and disempowered the Sorcerers of the Thousand Sons with their insidious silence, the Sisters struck, surging through the recoiled mass of Space Wolves, and began to hack and slice with their Power Swords. The Space Wolves moved alongside the Null Maidens to take advantage as the Thousand Sons wavered in their attacks. But the Thousand Sons managed to rally and concentrate their efforts against the Untouchable warriors, thinning their ranks until they were able to once again make use of their psychic abilities.
Some of the Captains of the Thousand Sons attempted to reform their lines and launch a counter-attack into the formidable lines of the Space Wolves. Using their psychic abilities the Thousand Sons managed to drive a wedge into their foes' line and firmly reestablish their defence. But this small victory was short-lived with the arrival of the Wolf King and his bodyguard of Terminators. Realising that their doom was finally upon them, the commanders of the Thousand Sons attempted to eliminate the Space Wolves' Primarch. Captain Auramagma of the Pyrae Cult attempted to slay the Wolf King by launching an attack of concentrated flame. This only momentarily staggered Russ and he somehow managed to nullify the Aetheric attack and reflect Auramagma's attack upon him, incinerating him with his own Warp-spawned fire.
The Thousand Sons' line could not hold against the unbridled savagery of Leman Russ, as their final stand was made in the shadow of the Pyramid of Photep. Shards of crystalline glass floated on the waters surrounding Magnus the Red’s lair. The surviving populace of Tizca, who had escaped the initial wrath of the invaders, sheltered within.
The Thousand Sons also faced the wrath of the bestial Wulfen, the mutant Astartes of the Space Wolves that suffered from the genetic curse of the Canis Helix contained within their gene-seed. Their razor-sharp fangs and talons tore into the ranks of the battered Thousand Sons. Only the most accurate shots would put them down, and they shrugged off wounds that would have killed even an Astartes. Their claws tore through Ceramite with ease, and their teeth were as vicious as any energised power blade. The Wulfen's single-minded savagery was unlike anything the Thousand Sons had fought before, and they fell back from these newly unleashed terrors, horrified that the Space Wolves would dare employ such degenerate, mutant abominations.
The Wulfen punched a bloody hole in the Thousand Sons’ line, tearing it wider with every second, and dozens of Astartes fell beneath the tearing blades of their claws. Howls of triumph filled the air as the gap the Wulfen had opened was filled with Custodes and Space Wolf warriors. Bands of Thousand Sons were surrounded and hacked down by frost-bladed axes and the glittering power fields of Guardian Spears.
The Thousand Sons' First Captain, Ahzek Ahriman, backed along the great basalt causeway over the water towards the Pyramid of Photep, their last refuge on Tizca. The best and bravest of the Legion, all that survived to sell their lives in sight of their Primarch, went with him towards the bronze gates that led inside. The howling of the Wulfen built to a deafening crescendo. And high above, those howls were finally answered.
Magnus' Final Command
Magnus the Red finally answered the pleas of his dying sons as he made his presence known. He presented a glorious sight, clad in golden Artificer Armour, his wild red hair ablaze with psychic energy. His flesh burned with the touch of immense power, greater than anything it had ever contained before. His bladed staff threw off blinding arcs of lightning that destroyed armoured vehicles in thunderous explosions. Magnus swept his one good eye across the horrified Space Wolves, and all who met his gaze died in an instant as they were driven to madness by the stygian depths of infinite Chaos they saw there. Only Leman Russ and his Fenrisian Wolf companions stood unfazed by the sorcerous power of Magnus, a gleam of anticipation in the Wolf King’s eyes, as though he relished the idea of the coming conflict with his brother.
Using his powerful sorcery, Magnus slowed time down in order to issue his final orders to his most favoured son and senior Captain, bidding Ahriman to lead the surviving Astartes of the Thousand Sons within the Pyramid of Photep. There, Magnus' Equerry Amon awaited him, bearing a priceless gift for Ahriman to bear away from Prospero. The Primarch reached down and touched the jade scarab in the centre of Ahriman’s breast-plate. The crystal shone with a pale light, and Ahriman felt the immense power resting within it. Magnus explained that this crystal had been cut from the Reflecting Caves of Prospero, and that every Astartes of the Thousand Sons Legion bore one set in his Power Armour. When the moment came, Ahriman would know what it was meant to do, and that he was to concentrate all of his psychic energies on the this crystal and those of his Battle-Brothers. Not fully comprehending his Primarch's cryptic words, Ahriman reluctantly withdrew within the pyramid as instructed, followed by the remaining Thousand Sons as Magnus once more restored the flow of time to its proper course.
Masses of people filled the Pyramid of Photep, terrified civilians and exhausted soldiers of the Spireguard. The Thousand Sons poured inside, their armour black and dripping from the nightmarish deluge of ash drowning the world beyond. The horrifying scale of the loss staggered Ahzek Ahriman -- at a conservative estimate, he guessed that just over a thousand Astartes had escaped the attack of the Wulfen. Only a tenth of the Thousand Sons Legion had survived the Spaces Wolves' furious assault. Pushing down his grief, Ahriman searched for Amon. The Equerry held a chest up for Ahriman to open. Ahriman reached up and took hold of the lock, which snapped open at his touch. He opened the lid and drew in a breath as he saw the book within, its cover red and cracked with age, for it was none other than the legendary Book of Magnus, the complete summation of his Primarch's knowledge of sorcery and the Warp. Ahriman was now its guardian. Ahriman understood with sudden clarity that Magnus had no expectation of surviving his duel with Leman Russ.
Ahriman soon found out that other senior members of the Thousand Sons had survived the Wolves' assault, including such Veterans as Amon, Hathor Maat and Sobek. But it soon became clear that a number of his fellow Thousand Sons had succumbed to the Flesh-Change during the height of the battle, including the Lore-Keeper of the Corvidae Cult. Dozens of Thousand Sons Battle-Brothers had to be put down due to the sudden return of rampant mutation. All told, only 1,242 Thousand Sons Astartes had survived the razing of Prospero.
The Crimson King Faces the Wolf King
The Crimson King and the Wolf King met in battle, with the fate of an entire world balanced on the outcome, and they fought like the gods of ancient Terran legends. Forking traceries of lightning shot upwards from the ground, isolating them from the host of the Space Wolves and the Custodes. Russ rained down blow after blow on Magnus, shattering his horned breastplate, and in return Magnus struck his brother with a searing blast of cold fire that cracked his armour and set light to his braided hair. The Wolf King’s Frostblade struck at Magnus, but his golden Power Axe turned the blow aside as they spun and twisted in an epic battle beneath the madness of a blazing storm of sheet lightning and pounding thunder. This was a battle fought on every level: physical, mental and spiritual, with each Primarch bending every ounce of their almost limitless power to the other’s destruction.
Magnus used his powerful psychic magicks, battering Russ with fists of telekinetic force wreathed in fire and lightning. Yet, Russ was a Primarch and such powers had little effect on him save to drive him to greater fits of rage. Magnus drove his fist into Russ’ chest, the icy breastplate cracking open and shards of Ceramite stabbed into the Wolf King’s heart. In return, Russ snapped Magnus’ arm back, shattering it into a thousand pieces. A blade of pure thought unsheathed from Magnus’ other arm, and he drove it deep into Russ’ chest through his shattered armour.
The psychic blade burst from Russ’ back and the Wolf King let loose with a deafening bellow of pain. A chorus from his Fenrisian Wolves added their howls to that of their master. The two enormous lupine monsters that accompanied Russ leapt upon Magnus, fastening their jaws upon his legs. Magnus slammed his fist into the black wolf's head, driving it to the ground with a strangled yelp, its skull surely shattered. With a bellow of anger, Magnus tore the white wolf from his leg with a thought and hurled it away over the heads of the army at Russ’ back.
Magnus and Russ were locked in battle high above the causeway to the pyramid, the furious horror of their struggle obscured by ethereal fire and bursts of lightning. A flare of black light erupted and Russ cried out in agony. His blade lashed out blindly and struck a fateful blow against Magnus’s most dreaded weapon: his eye. Magnus reeled back from the Wolf King, one hand clutched to his eye as his shattered arm crackled with regenerative energies. As broken and bloodied as Leman Russ was, he was brawler enough to seize his opportunity. He barreled into Magnus and gripped him around the waist like a wrestler, roaring as he lifted his brother’s body high above his head. All eyes turned to Russ as he brought Magnus down across his knee, and the sound of the Crimson King’s back breaking tore through the heart of every Astartes of the Thousand Sons.
The Wolf King howled his triumph to the blackened heavens. Russ dropped Magnus to the mud and brought the Frostblade Mjalnar around to take the head of his defeated brother. With the last of his strength, Magnus turned his head, and his ravaged eye found his favoured son, Ahriman, "This is my last gift to you."
Leman Russ’ blade swept down, but before its lethal edge struck, Magnus whispered eldritch words of power as his body underwent an instantaneous dissolution, its entire structure unmade with a word, and Ahriman gasped as vast and depthless power surged into his body. As it swept through him, he knew what he had to do. Ahriman clasped his hands upon the jade scarab set in his breastplate. He knew everything about that gem, and pictured the identical artefact on the chest of each Astartes of the Thousand Sons. Even as he visualised them, the power in him spread to the entire Legion as Magnus gave the last of his strength to save his sons, teleporting his beloved and infamous City of Light, Tizca, from the surface of Prospero and through the Warp and into the Eye of Terror, to rematerialise upon the Daemon World known as the Planet of the Sorcerers. This new world preserved all of their precious knowledge hidden within its libraries that the Thousand Sons had gathered from all across the galaxy during the Great Crusade, and the Thousand Sons were saved from their enemies -- at the cost of their souls.
Magnus had willingly sacrificed the flesh that had contained his essence, and in so doing, had ascended to the more evolved form of a Daemon Prince, one free from the constraints of mortality and the limits of reality. He now appeared before his surviving sons as a large humanoid form wreathed in the light of stars and the power of infinite possibility, with brilliant wings of shimmering Warp fire. Magnus the Red had become the first of the Daemon Primarchs, and later he ascended further to become a Lord of Change, a Greater Daemon of Tzeentch.
The Thousand Sons themselves succumbed to the "gift" of their patron and true saviour from the Fall of Prospero, the Chaos God Tzeentch -- the full return of their aberrant genetic mutations, which threatened to turn all of the surviving Thousand Sons into mindless, gibbering Chaos Spawn. Appalled by the return of the dreaded Flesh-Change, Ahriman led a secret cabal of the most powerful Thousand Sons Sorcerer Librarians who had survived the Fall of Prospero and guided them in the invocation of a powerful daemonic spell later known as the Rubric of Ahriman. The spell was successful, but its success came at a high price: those Battle-Brothers of the Legion who lacked psychic abilities were transformed into living automatons. Their bodies were reduced to dust, and their souls were forever sealed within their suits of Power Armour -- every joint magically sealed, forever trapping the souls within in a nightmare existence of living death.
The minority of Thousand Sons Astartes who did possess psychic abilities and so did not succumb to the Rubric soon found their psychic abilities increased to a tremendous degree by the power of the spell. The ritual also accomplished its goal, halting the dreaded mutations, both in the surviving sorcerers and their undead brethren. Magnus was enraged by Ahriman's audacious spell and what it had done to his sons, but was secretly pleased with the level of sorcerous knowledge the Legion had attained through their metamorphosis. Confronting the cabal who had carried out the Rubric, Magnus nearly slew Ahriman in his rage, but Tzeentch intervened personally, sparing Ahriman's life, for he had proven to be a useful pawn.
Magnus exiled Ahriman and his remaining collaborators from the Planet of the Sorcerers and ordered them to forever roam the galaxy in search of understanding and knowledge of the true meaning of Chaos, a quest that continues unto the present day.
The Bloody Tally of Justice
All told well over thirty million lives were lost in the prosecution of the Emperor's justice on Prospero, the vast majority of these deaths being those citizens of the Imperium on the planet at the time of the Imperial Censure Fleet's arrival. Official records place the number of survivors from Prospero's civilian population at zero, and while in actuality there were certainly some thousands at large in the galaxy or who potentially escaped with one of the few bands of Thousand Sons to leave the planet alive, as a people the Prosperine branch of Mankind was now extinct. Of the Thousand Sons, official records before 014.M31 no longer listed the Legion, assuming it was completely destroyed until the Siege of Terra. Again, the actual truth is somewhat different, but still places the losses incurred for those Thousand Sons on Prospero at the time of the fleet's arrival at near-total, with the survivors scattered across the galaxy.
Some of those Thousand Sons detachments fighting in the Great Crusade elsewhere in the Imperium were to be destroyed by their allies before news of Prospero's destruction reached them: 2,000 under Sentor Rahme of the Ninth Fellowship were slaughtered in their encampments by the Ultramarines attached to the same force, and 300 Veterans of the Seventh Fellowship were abandoned to their deaths during the assault on Maktor VIII by the Imperial Fists to name but two of the more prominent cases. Of all the main contingents of the Thousand Sons abroad in the galaxy, only two were known to have escaped Imperial justice, the majority of the Fourth Fellowship, some 5,000 Legiones Astartes who abandoned their Great Crusade assignment after hearing of the attack on Prospero, and a force, perhaps of several thousand, of the Sixth Fellowship present on Zhao-Arkhad, as part of the agreement between the Legion and that distant and enigmatic Forge World. Worse still for the Legion, the destruction of Prospero and their status as Renegades left them bereft of all support and succour within the borders of the Imperium, with no means to resupply or recruit, barring open piracy.
The Censure Host fared only somewhat better, taking combined casualties of perhaps 49,000 in total and a far greater toll of munitions and machinery either destroyed or abandoned on Prospero. Driven by the cold rage of their Primarch Leman Russ to engage in some of the bloodiest fighting of the campaign, the Space Wolves suffered the heaviest casualties, with some 25,000 listed as killed in combat, and several thousand more besides, mostly of the Thirteenth Great Company simply listed as missing. The figure constituted a substantial amount of the Space Wolves' total strength and by the formal outbreak of the Horus Heresy, a mere handful of solar months later, they'd had little chance to replenish their numbers. Just as serious for the Space Wolves was the expenditure of munitions and equipment -- such was the zeal with which they prosecuted the war on Prospero that their reserves of such things were badly depleted and left them unable to engage in more than limited warfare during the early stages of the Heresy.
The Imperial Army units attached to the Censure Host, although an auxiliary, also suffered badly in the fighting, with an estimated 23,000 dead. Indeed, several units were simply disbanded or merged with other formations on their return to Terra. The Legio Custodes and Silent Sisterhood suffered relatively light casualties by contrast, although considering the smaller relative size of those forces, they could still be considered severe. Perhaps more telling was the damage done to the Legio Custodes' mythical invincibility in the minds of some -- for during the fighting on Prospero, some of their number had been engaged and beaten by mere Space Marines, a lesson that would be remembered by certain of the Astartes in later years. However, the wiser minds among the Legiones Astartes noticed the ease with which the Custodians had despatched their kind in turn, and wondered uneasily if perhaps this had been the very task they had originally been made for.
Order of Battle during the Fall of Prospero
The Defenders of Prospero
Being a roster of those military formations and notable leaders to have stood in defence of Prospero during the assault of the Imperial Censure Host in 004.M31. All those here named are declared Traitoris Extremis for the base act of raising arms against the rightfully empowered agents of the Emperor of Mankind, and all rights of sanctuary or redress under Imperial law are forfeit.
Senior Officer Cadre
- Magnus the Red, Lord of the XV Legion, Warden of Prospero - Deemed to be in violation of the Conventions of Nikaea and the Emperor's Decree Absolute.
- Lucretia Elunnirai, Seneschal Prime of the Prosperine Guard - Commander of the Planetary Defence Forces of Prospero.
- Magus Prime Tacitus Proctor, Forge-domini of the Prosperine Zhao-Arkad enclave and Eminarii Order - Declared 'Heretek in absentia' by the assembled conclave of the Martian Orders of the Mechanicum.
- Calvar Ibranum, Princeps-warden of the Legio Xestobiax Prospero Vigil
Known to be on Prospero at the time of the Space Wolves' assault were representatives of all of the various Fellowships of the the XV Legion, the Thousand Sons, as well as the commanders of all except the Fourth Fellowship. In total, it is estimated that of the Thousand Sons' known total strength of perhaps 80,000-90,000 Astartes, there were approximately 62,000 present on Prospero by judgement of after-action reports (many of which are contradictory), either within the capital city of Tizca or one of the smaller outposts elsewhere on the planet. Those Fellowships and Orders known to have at least a portion of their number present for the battle are recorded below:
- The First Fellowship, commanded by Chief Librarian Ahzek Ahriman - 9,000 Space Marines, comprising the majority of the Thousand Sons Terminator units and recently returned to full strength.
- The Second Fellowship, commanded by Phosis T'Kar - 7,800 Space Marines. As with most of the Fellowships, this comprised a mix of unit types divided along Cult and Order lines.
- The Third Fellowship, commanded by Hathor Maat - 8,200 Space Marines, reinforced from recent campaigns to near full strength.
- The Fifth Fellowship, commanded by Baleq Uthizzar - 6,200 Space Marines, reduced in strength after recent campaigns and with some companies operating on campaign.
- The Sixth Fellowship, commanded by Khalophis - 4,000 Space Marines. It is believed that a full half of the Sixth's active strength was deployed to the sectors around Zhao-Arkhad in the galactic south.
- The Seventh Fellowship, commanded by Phael Toron - 7,200 Space Marines, reduced in strength after recent campaigns and with some companies operating on campaign.
- The Eighth Fellowship, commanded by Auramagma - 8,400 Space Marines, reinforced from recent campaigns to near full strength.
- The Ninth Fellowship, commanded by Magistus Amon, Equerry to the Crimson King, commander of the Hidden Ones - 7,900 Space Marines, reduced in strength after recent campaigns and with some companies still active that were beyond recall range.
- The Order of Ruin - 1,900 Space Marines and 800 Battle-Automata. It is believed that approximately half of the Order of Ruin was attached to Thousand Sons detachments operating on campaign across the galaxy or despatched in the holds of the fleet.
- The Order of the Blind - 888 Space Marines. It is believed the entire complement of the Order had heeded Magnus' recall, arriving on Prospero via mysterious means before most other units.
- The Order of the Jackal - 604 Space Marines, divided into detachments attached to each Fellowship and contingent on Crusade.
- The Prosperine Guard - Comprising three distinct bodies; the Spireguard, Airguard and Expeditionary regiments. The Prosperine Guard regiments were outfitted to various standards, but in all cases were considered well-trained and equipped. Estimates place some 85,000 soldiers within the various barracks and training facilities of Tizca and smaller outposts scattered across Prospero at the time of the invasion.
- Northern Palatine Guard - This Imperial Army regiment, under the command of Colonel Katon Aphea, was deployed on the edges of the burning port of Old Tizca, which occupied the high parapets of the overlooking libraries and galleries of the Nephrate District. The Northern Palatine Guard were overran by Leman Russ and his Space Wolves in less than two solar minutes.
- Prosperine Spireguard - The primary Imperial Army regiment tasked with the defence of Prospero. There were some survivors of the Spireguard who were present at the Pyramid of Photep at the conclusion of the battle. Their fates remain unknown.
- 15th Prosperine Assault Infantry - The 15th Prosperine Assault Infantry was an Imperial Army regiment under the command of Captain Sokhem Vithara. They defended the old eastern quarter of the capital city, known as Old Tizca, from the initial ground attack of the Space Wolves Legion.
- Prospero Assault Pioneers - An Imperial Army regiment that rallied in defence of their homeworld after the majority of their regiment was wiped out when three of their four barracks were destroyed in the initial orbital bombardment. It is assumed that they were slain to a man during the battle.
- Skyguard Air Command - Prospero's primary air force. They launched every squadron of their two-man anti-gravity skimmers from their hangars to the south of Tizca. Armed with Heat Lances and Missile Pods, their disc-like aircraft duelled for supremacy with the Loyalist forces above the skies of Tizca. It is assumed that they were annihilated in the ensuing conflict.
- Zhao-Arkhad Taghmata - The defence forces of the autonomous Zhao-Arkhad collective were present within their enclave in the wilderness of Prospero as part of a treaty for the supply of the Legion. They consisted mainly of various combat-automata and other mechanised units, numbering perhaps 8,000 warriors and automata. Almost none of these were present within the city of Tizca and dwelt within the subterranean Geller Barrier-screened fane.
- Legio Xestobiax - A full Vigil of the Legio Xestobiax was stationed within the Zhao-Arkhad enclave, comprising some twelve Titans of varying marks. As with their Zhao-Arkhad overlords, the Prospero Vigil of the Legio Xestobiax was stationed outside the city of Tizca and ensconced in vast underground bunkers in their enclave.
- Citizen Militia Regiments - In theory, a large percentage of the adult population of Tizca could be marshalled for war and issued weapons form the reserve armouries scattered throughout the city, creating a force of men-at-arms numbering in the millions. However, in practice such a force was of negligible strategic value considering its lack of training and effective leadership.
- I Helikon Legion and the Magdan FreeKorps - Both of these regiments of the Imperial Army had been re-reouted some solar months prior to the attack on Prospero to resupply and layover at Tizca awaiting pick-up and redeployment after their completion of the Tigarth Pacification. The off-world regiments were stationed in general barrack blocks on the outer edge of the city designed for such transitioning forces, and were effectively cantoned there without access to the city. These two regiments, one of mechanised infantry and the other of lightly equipped skirmishers, shared little in common save that both originated from newly Compliant worlds whose governors bore little personal loyalty to the newly appointed Warmaster Horus. In both cases, the orders that saw them transferred to Prospero at such short notice came from officers assigned to the Warmaster.
The Censure Host, Beta-Garmon Contingent
Being those units assembled on Beta-Garmon to prosecute the Writ of Censure issued by the Emperor's hand in 004.M31 decreeing that Magnus the Red, Lord of Prospero and the XV Legion of the Legiones Astartes, be brought in disgrace to Terra, there to face the judgement of his father.
Senior Officer Cadre
- Leman Russ, Primarch of the VI Legion, Lord Regent of Fenris, Commanding General of the Censure Fleet - Granted the Emperor's deferment over his brother Primarch Magnus, and the right to mete High Justice within His realms to meet this end.
- Overseer Boros Kurn, Commander of the 16th Independent Assault Battalion, XVI Legion, the Sons of Horus - Emissary of the Warmaster.
- Princeps Senioris Maldis Drane - Commanding Princeps of the Legio Mortis.
The VI Legion, the Space Wolves -- comprising an approximate total of 73,200 Space Marines, including contingents previously on detached duties in proximity to Fenris or Beta-Garmon, and recalled for the Prospero campaign. (Companies are noted here using both the numerical designation used by the Divisio Militaris records and the more archaic titles used during available recitations of the Saga of Prospero -- additional notation of current observable operational factors from Beta-Garmon data included):
- Great Company Onn (One), The Breakers of Rings, commanded by Jarl Gunnar Gunnhil (Lord Gunn). 3,000 Space Marines, primarily formed of Varagyr Huscarl units equipped with Terminator Armour and fighting as bodyguard, and also comprising additional Legion command elements.
- Great Company Twa (Two), The Thread-cutters, commanded by unknown Jarl. 800 Space Marines, believed to comprise veteran infantry units relived from special duties with attached Dreadnought contingent (approximately 60 individual armours of varied patterns). Jarl unknown.
- Great Company Tra (Three), The Eagle's Keepers, commanded by Jarl Ogvai Ogvai Helmschrot. 9,800 Space Marines, mostly close assault infantry and support armour (noted in extemporaneous data as being proportionally high in Initiate-status Legiones Astartes).
- Great Company For (Four), The Blood-worm's Masters, commanded by Jarl Hvarl Red-Blade. 8,600 Space Marines, comprising heavy infantry and self-propelled artillery, including a large number of Breacher and Assault units (ref. "Bloodied Claw" tactical formation sub-type).
- Great Company Fyf (Five), The Blood-ice Storm, commanded by Jarl Amlodhi Skarssen. 10,000 Space Marines, comprising a mixed infantry force with light support armour, assigned while on Fenris for resupply.
- Great Company Sepp (Seven), The Wight-flame's Wielders, commanded by unknown Jarl. 5,200 Space Marines, comprised mostly of warriors of the "Black Cull" and destroyer and immolation units.
- Great Company For-twa (Eight), The Slaughter-fire Heralds, commanded by unknown Jarl. 9,500 Space Marines, comprising principally reconnaissance and infiltration units (ref. "Pale Hunter" tactical formation sub-type).
- Great Company Tra-tra (Nine), The Serpents of the Battle-moon, commanded by Jarl Sturgard Joriksson. 7,800 Space Marines, comprising infantry support units and notable heavy weapons units, including Rapier weapons platforms.
- Great Company Elleve (Eleven), The Sea-flame's Bearers, commanded by Varald Helsdawn. 9,200 Space Marines, comprising veteran infantry, believed to include a large proportion of early-induction Terran recruits.
- Great Company Tolv (Twelve), The Shield-gnawers, commanded by Jarl Oki (called Scarred; successor to Jaurmag (called Laughing Jaurmag, who was sent to Terra before Prospero campaign). 8,700 Space Marines, comprising close assault infantry with strong contingents of ground assault vehicles.
- Great Company Dekk-Tra (Thirteen), The Corpse-renders, commanded by Jarl Jorin Bloodhowl. 600 Space Marines, comprising pursuit units and light assault infantry.
- The Legio Mortis - Twelve Battle Titans of the Death's Heads, forming two full and one demi-maniple, including the Warlord-class Aeterna Virtus as its command element.
- 19th Cthonian Headhunters Regiment - Slightly less than 9,000 assault infantry raised on Cthonia, infamous within the Imperialis Auxilia for their savage and belligerent temperament and tendency to mutilate the dead for trophies.
- 3rd Ydranian Seekers Regiment - Light infantry from the Ydran Cluster (notably a sector of human-occupied space devastated by rogue psykers prior to Imperial Compliance at the hands of the Death Guard). Organised into three cohorts of 4,000 soldiers each and believed equipped with a variety of non-standard psi-warding technolgies -- the effectiveness of which deemed dubious by the Mechanicum.
- 73rd and 75th Echelons of the Hosts of Brass - Heavy infantry. Notably recruited from the sub-tech world of Brass, whose feudal lords long indoctrinated the population against the potential threat of "sorcerers" and other psychic phenomena. Numbering 8,000 per cohort and equipped with a variety of primitive but effective close assault weaponry and chemical slugthrowers.
The Imperial Censure Host, Terran Contingent
Being those units that were assembled on the Throne World of Terra to prosecute the Writ of Censure issued by the Emperor's hand in 004.M31 and decreeing that Magnus the Red, Lord of Prospero and the XV Legion of the Legio Astartes, be brought in disgrace to Terra, there to face the judgement of his father.
Senior Officer Cadre
- Constantin Valdor, Captain-General of the Legio Custodes - Granted the Emperor's Seal and the right to mete High Justice within His realms.
- High Marshal Markas Rhone, Commander of the 3rd Terranic Auxilia and senior officer of the Excertus Imperialis.
- Jenetia Krole, Senior Vigil-Commander of the Silent Sisterhood
- Dominus-Xelatcus Thrane Esmark, Commanding Princeps of the Chamber Occidentalis of the Ordo Sinister
- The Legio Custodes - 982 warriors constituting 91 separate Sodalities of the Legio Custodes.
- The Silent Sisterhood - Estimated 3,000 Sisters-Militant, constituting three full Vigils of the Silent Sisterhood.
- 3rd Terranic Auxilia - 5,000 Terran troopers of the Terranic Auxilia, known informally as the "Ironside Brigade," recruited primarily from Old Albia.
- Tyrian Exo-guard, Cohorts Siris, Asag, Rabisu, Asakku, Kur, Edimmu, Siduri and Atra - Each cohort consisting of 600 void-armoured Exo-guard and 100 helot auxiliaries.
- 9th Solar Auxilia Cohort - One of the renowned Saturnyne Rams regiments, 4,000 void hoplites and support vehicles.
- 10th and 42nd Sarcosan Voltigeurs - Recent arrivals on Terra in the wake of the Dark Angels campaign to bring their homeworld to Imperial Compliance. Each regiment comprised approximately 3,000 light infantry with a small detachment of Terranic Overseers.
- Charonid Sentinels, Third Fane - A full detachment of the dour, heavily augmented watchmen of the outer Sol System, replete with their full panoply of otherwise proscribed weaponry. The Third Fane numbered slightly more than 2,000 men-under-arms.
- Sydonian Taghmata Elements Ekriss, Norne and Ifrem Taghma - A small force of Mechanicum warriors, attached to the Censure Host as observers and to affect the inspection and potential dismantling of any Mechanicum assets or prohibited technology present on Prospero. (Note that the inclusion of this force seems to have been in response to a late and direct request from the Fabricator-General of Mars.
- The Chamber Occidentalis of the Ordo Sinister - Five Psi-Titans of the Ordo Sinister, all Warlord-class Psi-Titan machines.
- Secutarii Sinister - Approximately 1,000 Secutarii of the Ordo Sinister, attached to the force as support troops for the Chamber Occidentalis.
Other Notable Imperial Personnel
- Othere Wyrdmake (Deceased) - Rune Priest of the 5th Company killed by Chief Librarian Ahzek Ahriman of the Thousand Sons
- Aun Helwintr - Rune Priest of the 3rd Company
- Bjorn - Astartes, 3rd Company
- Godsmote - Astartes, 3rd Company
- Jormungndr - Astartes, 3rd Company
- Kasper Ansbach Hawser - Skjald of the Space Wolves Legion's 3rd Company and a secret, deep-cover member of the 'Hidden Ones' (the Scout Auxilia) of the Thousand Sons Legion.
- Lemuel Gaumon - A Neophyte under Azhek Ahriman.
- The Horus Heresy - Book Seven: Inferno (Forge World Series) by Alan Bligh, pp. 22-32, 38, 65
- A Thousand Sons (Novel) by Graham McNeill, pp. 225-226, 228-229, 230, 236, 241, 244, 255-259, 262-263
- Prospero Burns (Novel) by Dan Abnett, pp. 339, 342-343, 350-351, 353-355
- Age of Darkness (Anthology) edited by Christian Dunn, "Rebirth" by Chris Wraight
- The Outcast Dead (Novel) by Graham McNeill
- Horus Heresy: Collective Visions, pp. 91-94, 97-98, 138, 236-237, 240-241