Black Legion - Age of Betrayal, M30-M31: First Pacification of Luna (703.M30) - This early Imperial campaign was the first operation mounted by elements of the early Space Marine Legions beyond the skies of Terra. The Unification Wars were still raging across the surface of Mankind's birth world. Luna was the bastion of a conglomeration of resurrectionist gene-cults whose members believed that human nature was both fractal, fractured and transcendent. Each of these Selenar gene-cults clung to a different set of archetypes. Every cult member was a product of creation by the Selenar gene-wrights according to formulae crafted in the Dark Age of Technology. Resurrected in body time and time again they sought to distill the true personification of a single human archetype. In their subterranean complexes the cults were powerful, insular and resistant to the Imperial Truth. The Imperials would have normally dealt with these insular cults in the usual matter they handled all of the other Terran factions and techno-barbarian states that refused to accept the rule of the Emperor of Mankind -- by obliteration. The fact that the Selenar gene-cults had something that the growing Imperium needed complicated that position. The Selenar returned the Imperial entreaties for alliance with silence. As the threats of the Imperium soon began to outnumber its offers, the Selenar cults began to gird themselves for war. So it was that the Emperor finally ordered Luna to be pacified by the sword, their superstitious beliefs cast down before the Imperial Truth and their gene-craft yoked to the needs of the Imperium. To this task the Emperor set the three of His newborn Space Marine Legions most suited to this purpose on what some Imperial chroniclers name as the first true battle of the Great Crusade. The combined force of the VIIth, XIIIth and XVIth Legions (later named the Imperial Fists, Ultramarines and Luna Wolves) lifted from the surface of Terra in a scattering of rocket flame. The as yet unnamed XVIth Legion had been chosen to serve as the Space Marine force's vanguard, and had brought its full strength to bear. Cutting power to their assault craft, the Astartes of the XVIth Legion drifted silently towards Luna through the void like arrows fired into the night. As the smaller wave of assault craft belonging to the VIIth and XIIIth Legions approached the airless world, the Selenar defensive weapon systems embedded in Luna's surface lashed the oncoming Imperial force. The XVIth Legion's assault craft, unlooked for and unseen, struck their targets like a dagger in the night. Within six hours of the first shot being fired, Luna had been pacified and brought into Imperial Compliance, the first off-world conquest of the Imperium of Man. Faced with annihilation, the surviving Selenar cultists bent the knee instead, their surrender communique transmitted to Terra calling for the Emperor to "call off his wolves". Broken and humbled, the enslaved gene-wrights of Luna would help forge the next generation of Space Marine who would carry out Mankind's conquest of the stars. As for the XVIth Legion, they had earned their name -- the Luna Wolves.Hunting of the Ak'Haireth (Unknown Date.M30) - An alien menace known variously as the Ak'Haireth, or "Bone Drinkers" in the vernacular, were fungoid, predatory and parasitic life forms which acquired their sentience from operating as physically interwoven gestalt "blooms". Their existence was fuelled by the slow and agonisingly painful siphoning of nutrition from living animals, primarily human bone marrow. Given to no technological creativity of their own, the Ak'Haireth operated at the edge of the western Segmentum Solar, inhabiting the scavenged void ships of other species and raiding isolated colonies and Feral Worlds unable to resist their predations. Initially encountered in the early years of the Great Crusade, the Ak'Haireth had been subjected to extermination pogroms carried out both the Luna Wolves and the VIIIth Legion (not then yet formally known as the Night Lords) which had been thought to have been successful. However, a cowardly species, the Ak'Haireth had been wont to flee if not cornered in battle, and over time it became apparent that some marrow-blooms of the foul xenos had hidden themselves and survived. By 986.M30, reports of attacks against isolated outposts and shipping in the region of the stellar wastes near Olmec indicated that the Ak'Haireth were again dangerously growing in strength and number. The Alpha Legion, only a handful of years previously united with their Primarch, was assigned the order for the xenocide of the species before it could spread further, and in a successful campaign that lasted three years, the Bone Drinkers were all but wiped out.Fall of Reillis (Unknown Date.M30) - For the first thirty years after his discovery, Horus Lupercal and the Emperor had many occasions to fight alongside one another. At the fortified city of Reillis, a human settlement unwilling to accept the Imperial Truth, the defenders used secret tunnels to infiltrate behind the besieging Imperial army and hundreds of enemy shock troops swamped the Imperial command encampment. Unprepared and unarmoured, the Emperor and Horus fought back-to-back until a plasma blast stunned the young Primarch and sent him staggering to the ground. The Emperor stood over His fallen son and refused to give ground until reinforcements arrived to drive their attackers back.The Gorro Hollowing (Unknown Date.M30) - Within the Telon Reach was an Ork empire that rivalled that centred on Ullanor, and at its heart was the scrap world of Gorro. The Ork tech-caste, the Mekboyz, dominated the Orks of Gorro and had made the world their own. The dominant tech-caste on Gorro seemed to be fascinated by a form of plasma technology never encountered before or since. Capable of generating destructive yields of terrifying potency, these plasma weapons had done much to blunt the Great Crusade's advance across the Telon Reach. The Emperor decreed that Gorro must be destroyed. When a thousand-strong fleet of warships dropped out of the Warp above Gorro it was the Emperor Himself who gave the order to begin the assault. Horus, ever the dutiful and favoured son, stood at the Emperor's side and watched as tens of thousands of assault craft spread out from the fleet. The Luna Wolves teleported into the scrap layers beneath the planet's surface, forced to hollow out Gorro from within due to the planet's high resistance to orbital bombardment. In the vanguard was the Emperor and by His side was Horus and a guard of black-armoured Justaerin Terminators from the Luna Wolves' 1st Company as well as the golden-clad warriors of the Legiones Custodes. As the Space Marines attacked, the Ork resistance they faced was nearly overwhelming. The Orks of Gorro were huge and augmented with scavenged bionics. Some stood taller than Dreadnoughts and their weaponry burned through Power Armour easily. At the height of the battle, the fury of the Orks split the Emperor from His guards. Alone He slew hundreds of them until a blast from an Ork plasma weapon weakened His defences and one of the Ork leaders seized Him. The creature's strength was so great that it took hold of the Emperor and buckled His armour. As the creature's grasp closed to throttle the Master of Mankind, Horus stormed through the press of battle and cut the Ork's arms from its body with a single blow. Together father and son led their forces deeper into the vast sphere of scrap until they reached the centre of Gorro. The Emperor worked to collapse the self-sustaining plasma sphere that powered much of the world's scavenged Ork technology and that contained a Warp-fold envelope, so that Gorro would implode into the Warp. The Emperor proved successful, and without its power source, the scrap world collapsed in on itself. A hollow skin of rusted metal around an empty void was all that remained to mark the death of the great Ork empire of Gorro. Horus had returned the favour of the Emperor saving his life on Reillis. This incident helped to forge an unusually close bond between the Emperor and His gene-son, closer than that between any of the other Primarchs and their father.War in the Shedim Drifts (Unknown Date.M30) - During the war in the Shedim Drifts against the marauding Eldar of Craftworld Mór-ríoh'i, a vast Imperial force comprised of no less than four Titan Legions which consisted of the Legio Atarus, Legio Mortis, Legio Fureans & Legio Osedax, was assembled and placed under the overall command of Commander Horus Lupercal and his Luna Wolves Legion. The apocalyptic battle which raged upon the planet's surface saw a full demi-Legio of the Legio Atarus encircled and all but destroyed. The Lupercal had cruelly used them, without their foreknowledge or consent, as a ruse to divert the strength of the enemy away from the direct defence of their craftworld while his Legion undertook a surprise assault against it. The war of the Shedirn Drifts was a great victory for Horus and all those of the Imperium who fought in the campaign gained glory because of it, but at the expense of the Legio Atarus, an injury that the Firebrands would not forget.Castigation of Terentius (Unknown Date.M30) - When the forces of the Great Crusade first entered the Ordoni Cluster, they encountered the formidable warlord Vatale Gerron Terentius. Observing the forces arrayed against him, Terentius was forced to take the path of survival and surrendered to the Imperium. The Imperium had need of men like Terentius, and the Great Crusade gave him opportunities and riches such as he had never dreamed. Given a small fleet of warships and a handful of Imperial Army regiments, Terentius grew his forces by conquest. For five decades he rose in power and reputation, conquering worlds around the Halo Stars in the name of the Emperor. At the height of his powers, he had the ear of Malcador the Sigillite and the countenance of several Primarchs. When he finally turned against the Imperium, many were shocked. Terentius began to conquer already Compliant planets, his contra-Crusade conquering system after system in his own name, rather than for the sake of all Mankind. Soon he had entire fleets of warships, tens of millions of soldiers and the loyalty of a hundred human-settled worlds. Ringed by fortress worlds, this rebel human empire began to eat up Imperial worlds around the Halo Stars. The Imperium responded by sending Horus and his Luna Wolves Legion to not only break the Renegade but to demonstrate to any others who harboured similar ideas within the Imperial forces the inevitability of a betrayer's defeat. Horus elected to not only use his Legion to complete the task at hand but sent personal requests to his brother Primarchs for support which saw substantial strength from the Night Lords, Iron Hands, and the Alpha Legion joined to the might of the Luna Wolves. Soon the rebel forces were fragmented, driven by tales of culled worlds. It is said that it was at the very moment that Terentius realised he could not win that the Luna Wolves came for him. As they dropped from the Warp within weapons' range of Terentius' warships they annihilated half of his command fleet in one fell swoop. Horus himself teleported onto the bridge of Terentius' flagship along with 50 of the Luna Wolves 1st Company's elite Justaerin Terminators and slaughtered all they found there. Terentius died unrepentant, ending his life impaled upon Horus' Talon. With Terentius dead, his rebellion crumbled as the castigation continued with renewed fury. Horus, his pride slighted by Terentius' decision to betray the trust the Primarchs and the Emperor had once put in him, is said to have ordered the Night Lords to decimate every world within Terentius' rebel empire. The power of the Iron Hands and elements of the Ordo Reductor were brought to bear on every structure on Terentius' bastion worlds. Soon the rebels of his realm were slaughtered, their cities smashed to dust, and his homeworld's very air laced with toxins. Once the castigation was complete, Horus sent the gold-dipped skull of Terentius to Terra with the ironic warning carried on the lips of the messenger who bore it, "So perish all traitors".Compliance of Molech (869.M30) - The Luna Wolves took part in the massive Imperial Compliance campaign on the newly discovered Knight World of Molech, which was led by the Emperor Himself, and included multiple Legiones Astartes, including the Dark Angels, Emperor's Children and the White Scars, as well as thousands of troops of the Imperialis Auxilia and assets from the Mechanicum and Legio Titanicus. After achieving victory, Cyprian Devine of House Devine was named Planetary Governor of Molech. In the presence of several of His Primarch sons, the Emperor led them to a Warp portal hidden underground, where He proceeded to enter into the Realm of Chaos to parley with the Ruinous Powers. When He finally returned, the Emperor appeared aged, but much more powerful. He then suppressed His sons' memories of Molech and stationed a large garrison force comprised of nearly 100 Imperialis Auxilia regiments, three Legio Titanicus cohorts, and detachments from two Space Marine Legions to protect the secrets of the Warp portal on Molech.The Keylek Genocide (921.M30) - Early in the Great Crusade the Luna Wolves encountered the hostile alien reptilian race known as the Keylekid on the world of Keylek. The grotesque Keylekid were greatly skilled in the arts of combat, and rose against the XVIth Legion angrily the moment the 63rd Expeditionary Fleet made contact. This genocidal campaign proved to be a long, bloody, and miserable affair for the Luna Wolves. At this time Horus was referred to simply as "The Commander" by the Astartes of his Legion.Compliance of 63-8 (Davin) (941.M30) - The Feral World of Davin, codified as Sixty-Three Eight (63-8), was the eighth world brought into Imperial Compliance by the XVIth Legion's 63rd Expeditionary Fleet some 60 standard years before the start of the Horus Heresy. The indigenous feral warriors of this world briefly attempted to resist being conquered by the Imperium, but were forced to surrender as they were overwhelmingly outmatched militarily by the Astartes. The warrior tribes were allowed to remain mostly intact as they had impressed Horus with their courage on the battlefield and their willingness to learn to adapt to Imperial culture. The military campaign was brief, and the Luna Wolves departed after the surrender of the Davinites, taking with them their concept of the Warrior Lodge, which was quickly adopted throughout the Luna Wolves fleet. A detachment of the XVIIth Legion, the Word Bearers (then known as the Imperial Heralds), under the command of First Captain Kor Phaeron was left to shepherd the people of Davin into the light of the Imperial Truth. The Imperial governorship of the planet was given to Commander Eugen Temba of the Imperial Army, a close friend and confidante of Horus. Long after the 63rd Expeditionary Fleet departed the star system, the new Planetary Governor soon found that the inhabitants of Davin's moon refused to comply with Imperial rule. This would eventually result in Governor Temba and his Imperial garrison force being struck down by a sorcerous attack unleashed by Davinite shamans of Chaos on Davin's moon, an attack that would twist their perceptions away from their oaths of fealty to the Imperium, succumbing to the corrupting influence of the Plague God, Nurgle. Unknown to the Imperials, the entire population of Davin had long been servants of the Dark Gods of the Warp. The corruption of Temba and his Imperial Army garrison forces would ultimately necessitate the return of the Luna Wolves Legion 60 years later, and lead to the eventual corruption of Horus.Compliance of Darrowmar (Unknown Date.M30) - The Luna Wolves fought alongside the Night Lords Legion in bringing the world of Darrowmar into Imperial Compliance.Compliance of Tethonus (Unknown Date.M30) - The Luna Wolves fought against a xenos-adversary whose identity is not recorded in existing Imperial records while bringing the world of Tethonus into Imperial Compliance. This Compliance action was a long siege of the xenos fortress-states on Tethonus. Horus had tasked the masters of the Forge World of Diamat to create continental siege machines; vast artillery pieces that could devastate the most powerful fortifications. But the war machines took much longer for the forge masters to complete than planned. By the time they were finished, the campaign on Tehonus had been over for more than a standard year and a half, and Horus had moved on to other conquests. So the weapons were put into a depot on Diamat for the day when he would come to claim them. Fifty standard years later, Horus would reveal his perfidy at Istvaan III, and would send raiding forces to claim these siege engines for later use in his attempt to overthrow the Emperor of Mankind.Assault on Dahinta (Unknown Date.M30) - On the world of Dahinta, the Luna Wolves fought against a race of self-aware machines called the Overseers, who were led by the artificial intelligence known as the Archdroid. One of the Emperor's longest-standing commands was that no sentient machines could be allowed to exist, for they had nearly caused the extinction of Mankind when they had rebelled against their human overseers during the Dark Age of Technology. Despite heavy casualties amongst themselves, the thinking machines were wiped from the face of Dahinta by the savagery of the Astartes. Only after the campaign had ended was the full truth learned: the Overseers had been created by a vanished offshoot of humanity that had settled Dahinta, perhaps during the Age of Technology. The Overseers had cared for their lost masters' crumbling cities long after they had become extinct or left their homeworld behind.Battle of Gyros-Thravian (Unknown Date.M30) - The Battle of Gyros-Thravian was a massive joint Imperial Compliance action carried out by three Space Marine Legions, composed of the Luna Wolves, Death Guard and Imperial Fists against the extremely powerful Ork Warboss Gharkul Blackfang, one of the most powerful Ork warlords ever encountered up until that time. Despite the strength arrayed against the vile Greenskin, it were the Imperial forces who were soon on the verge of defeat. It was then that the Emperor Himself, aboard His flagship Bucephelus, came to the aid of His sons. He personally led a force composed of 1,000 Legio Custodes into the heart of the mighty Ork horde. Blackfang was confronted by the Emperor and killed atop his Gargant while the Custodians proceeded to lay waste to the rest of the Greenskin horde. The Custodians accounted for the slaughter of the Orks, slaying over 100,000 of the savage xenos, with the loss of only three Custodians. Following their momentous victory, the Emperor commemorated the Custodians' sacrifice by engraving the names of the three fallen Custodians into His own personal Power Armour.Pacification of Schravaan (Unknown Date.M30) - This was a joint Imperial Compliance conducted by the Luna Wolves, Iron Warriors, Imperial Fists, and the Emperor's Children Legions against the xenos Badoon on the world of Schravaan. The Iron Warriors won a great victory when they stormed the final refuge of the Badoon. They breached the defences and held while the other Legions carried the city beyond. During the following victory feast, Horus proclaimed Perturabo the greatest master of siege warfare in the Great Crusade. Fulgrim, the Primarch of the Emperor's Children then inquired to his brother Dorn whether he thought even the defences of the Imperial Palace could resist the Iron Warriors, in which Dorn replied that he regarded the defences as being proof against any assault if well-planned. Perturabo flew into a rage and unleashed unfounded accusations against his brother. After this the two rarely spoke, and neither Legion would serve again in the same campaign for the remainder of the Great Crusade.Compliance of Krypt (Unknown Date.M30) - The Compliance of Krypt was a relatively short campaign conducted during the Great Crusade by both the Luna Wolves and the Death Guard Legions against the Orks upon the frozen plains of the world of Krypt. Fighting together for more than a week across the frozen surface of the planet, the Space Marine Legions turned the blue ice dark with xenos blood. The Luna Wolves' Captain Garviel Loken and his 10th Company are known to have fought alongside Death Guard Battle-Captain Nathaniel Garro and his 7th Great Company at this time.Pacification of Zaramund (970.M30) - A joint-Compliance campaign that was conducted by the Luna Wolves and a contingent of Death Guard led by First Captain Calas Typhon and a contingent of Dark Angels led by Luther, the acting Regent of Caliban. Following their victory, a celebration was held, but soon the festivities were marred when an enraged Lion El'Jonson arrived to rebuke Luther for disobeying his orders to remain on Caliban.Disovery of Primarch Alpharius Omegon (ca. Late-970s.M30) - Extant accounts state that Alpha Legion Primarch Alpharius was discovered accidentally by the Luna Wolves when they were lured into a trap after receiving a distress beacon from one of their own battleships. When they went to assist, Horus' own flagship came under attack by an unknown enemy, and a single assassin broke into the flagship and fought his way clear to Horus' command chamber. Horus himself was forced to confront him, but thankfully, did not slay his attacker but recognised him instead as his lost brother; Alpharius. Unfortunately, the validity of this account is considered highly suspect.Tyrade System Compliance (ca. 998.M30) - The Luna Wolves served alongside a detachment of the Vth Legion, the White Scars, during the Imperial Compliance of the Tyrade System. This action occurred seven years before the Battle of Istvaan III and the start of the Horus Heresy.Compliance of Melchior (ca. 999.M31) - The Imperial Compliance of Melchior was a joint campaign that was carried out by both the XVIth Legion and the Blood Angels Legion. The world was the last bastion of the xenos known as the Nephilim -- hulking entities of roughly humanoid shape who were smooth like carvings of soapstone, with abstract shapes approximating arms and legs. Their dome heads emerged from their shoulders without a neck, and an array of olfactory slits and eye-spots ringed the surface of their skulls. In the light, the Nephilim looked like objects crafted of blown glass, their semi-transparent flesh glowing in the bright day. The Nephilim possessed an unhurried, careful agility like that of sea-going creatures seen through the walls of a glass tank. They moved deceptively slowly through air as if they were swimming in water, but they could move fast if they wished, darting and spinning, becoming difficult to hit. The alien giants, mocking humanity's great dream of peace and unity, had left a trail of destruction behind them that had claimed a hundred worlds before they had come to rest upon Melchior. Sagan, the DeCora Spine, Orpheo Minoris, Beta Rigel II; each of these planets had been denuded of all human life, populations herded into empath-chapels as big as mountains and then slowly consumed. Even their name, Nephilim, the name of the fallen seraphs, was a name taken from ancient human mythology -- that of Terra, Caliban and Barac. The true horror of it was that the Nephilim used those they preyed upon to do their soldiering for them, snaring the pliant, the lonely, the sorrowful with their ideal of an attainable godhood. They plied their victims with stories of eternal existence for the faithful, of endless sorrow for the agnostic; and they were very good at it. Perhaps the xenos really believed that what they were doing was somehow taking their victims closer to a form beyond flesh, to an afterlife in an eternal heaven-state; it did not matter. With their advanced technology they implanted bits of themselves into their thralls to further their communion. They cut their own flesh and made living masks to mark their devotees. The Nephilim controlled minds, either through the transmitted power of their will or through the weak character of those they chose. They were an affront to the Emperor's hope for the creation of the rationalist, secular galaxy outlined by the Imperial Truth. They represented not only an offence to the purity of a precious human ideal but in their insidious cuckoo-nest displacement of those who foolishly gave them fealty. For what the aliens fed upon, what the Scout Marines of the Blood Angels and Luna Wolves had seen and reported back, were the very lives of those who cherished them. The empty chapels were piled high with stacks of desiccated corpses, bodies that had been aged years in only hours as all living essence was siphoned from them. The Primarchs of the Legions were disgusted as the true understanding of the enemy they faced was revealed. The Nephilim fed on adulation. In the strategium of his flagship, the Vengeful Spirit, Horus showed his brother Sanguinius, the Primarch of the Blood Angels, the plan that he had conceived to break the will of the Nephilim. Horus wanted the Blood Angels to march shoulder-to-shoulder with their cousins, cowing the aliens with the sight of an army of thousands of powerful Astartes rolling without pause to the gates of their last bastion. And then through those gates, over the battlements, not stopping, not pausing to parley or hesitate. "Like the ocean these things sprang from", Horus had said, "we will roll over the aliens, drag them down and drown them." The sheer bombast of the plan was its greatest strength, but Sanguinius had not been easily swayed to it. This blunt, brute-force approach was better suited to their more intemperate brother Primarchs, to Leman Russ or to Angron. Sanguinius felt that neither he nor Horus were so artless, so focused upon the target to the detriment of all else, but in the end he agreed. When the time came to enact their audacious plan, Horus and his Luna Wolves met the xenos army on the sparkling white plains of the Silver Desert. Before open hostilities began, Horus attempted to parlay with the Nephilim one final time, but the overconfident xenos refused to capitulate, casually informing the humans that they could not win. Horus informed the xenos commander that it had made a grave error, for it would be the Nephilim who would fall. The Luna Wolves would be the anvil upon which the xenos would break, and the Blood Angels would be the hammer. With lightning speed, the heavens screamed as a rain of ceramite Drop Pods tore through the outer atmosphere of Melchior and fell like flaming meteors towards the Silver Desert. Falling with them were Stormbird and Thunderhawk assault gunships that turned and wheeled through the air towards the gargantuan Nephilim encampment, carrying company upon company of the IXth Legion. The speed of their assault was the key to victory; the alien invaders and their zealots had successfully been drawn out to confront the massed forces of the Luna Wolves, leaving the defences on their flanks thinned and permeable. But the xenos giants were not slow in their thinking, and the moment they understood that they had been duped, they would attempt to regroup and fortify. The Blood Angels did not allow that to happen. The Nephilim were broken and cut down, their cohesion shattered by the brutal deep strike. Caught between the brutal fury of two Space Marine Legions on Melchior's shining sands, the Nephilim were finally put to the sword.Ullanor Crusade (ca. 999.M30-000.M31) - The Ullanor Crusade was a vast Imperial assault on the Ork empire of the Overlord Urrlak Urruk during the Great Crusade of the early 31st Millennium. The capital world of this empire, and the site of the final assault, lay in the Ullanor System of the Ullanor Sector, which had long been under the dominion of Urrlak Urruk's Greenskin pocket empire. The Crusade included the deployment of 100,000 Space Marines, 8,000,000 Imperial Army troops, and thousands of Imperial starships and their support personnel. The Luna Wolves spearheaded the assault into the heart of Urlakk's fortress-palace. During the height of the assault, Horus and a retinue of Luna Wolves Terminators from the elite 1st Company came face to face with the massive Ork Warlord and a retinue of 40 Ork Nobs. Horus charged into the Nobs, hacking them apart with his Lightning Claws until he finally faced the Ork Overlord himself. Urlakk was simply no match for the Primarch's skill and unnatural power. First crippling his enemy, Horus hefted Urlakk's broken body out onto the roof of the Greenskin's palace and threw it screaming from the battlements to fall far below amongst the horde of Orks still assaulting the lower levels. Seeing their leader defeated sent a panic through the Greenskin forces, which started to fall back from the Terminators. But the fleeing mobs found they had nowhere to run, as the outer walls had been breached by the attacking Luna Wolves, and the day turned into a slaughter. In the Overlord's chamber, Horus found every Ork and Terminator dead, apart from the gore-drenched First Captain of the 1st Company, Ezekyle Abaddon, who was surrounded by crushed Ork bodies. The Ullanor Crusade marked the high point of the Great Crusade's vast effort to reunite the scattered colony worlds of humanity. The Orks of Ullanor represented the largest concentration of Orks ever defeated by the military forces of the Imperium of Man before the Third War for Armageddon began during the late 41st Millennium. Following the defeat of the Orks of Ullanor, the Emperor of Mankind returned to Terra to begin work on His vast project to open up the Eldar Webway for Mankind's use. In His place to command the vast forces of the Great Crusade He left Horus. Horus was raised to the rank of Imperial Warmaster and given command authority over all of his fellow Primarchs and every Expeditionary Fleet of the Great Crusade. But the Primarchs never came to terms with the Emperor's absence. Their hurt feelings over His seeming abandonment of the Great Crusade to pursue a secret project whose purpose He chose not to reveal to His sons laid the seeds of corruption that would ultimately blossom into the Horus Heresy. Yet the Emperor sent word from Terra that in honour of the great victory at Ullanor, the Luna Wolves should henceforth be known as the Sons of Horus, in honour of their Primarch's singular deeds, though Horus, with typical humility, chose not to rename his Legion at this time.Subjugation of the Akum-Sothos Cluster (ca. 000.M31) - The Aukum-Sothos Cluster, which had been brought into Compliance by the Luna Wolves early in the Great Crusade, mysteriously rebelled against Imperial rule due to the actions of controlling xenos. Horus had formulated a plan to cast down these so-called Unsighted Kings, the xenos-possessed leaders of the insurrection, in a lightning war that would purge the afflicted population while retaining the cluster's highly developed infrastructure for future re-population. The Warmaster's plan called for the bulk of four Legions -- the Luna Wolves, Space Wolves, Iron Warriors and Raven Guard -- to converge on the heavily fortified lair of the Unsighted Kings before a final, overwhelming assault was launched. Despite his misgivings, Corax complied, and assigned the majority of his Terran-borne veterans of the old XIXth Legion, especially those who readily agreed to the Warmaster's plans, as the assault's vanguard element. At the height of the battle, with the assault companies decimated and the attack faltering in the face of overwhelming fire, Corax himself led the forlorn hope, his battle cry firing the Legion to such efforts that the breach was carried and Gate Forty-Two taken. The honour of slaying the Unsighted Kings was claimed by Horus as Warmaster and at the moment of their execution, the xenos' hold over the population was dispelled. The Akum-Sothos Cluster was delivered and Horus' prize was reclaimed. The cost was terrible however, thousands of Raven Guard, the bulk of them Terran-born, had given their lives before the shattered walls of Gate Forty-Two.Compliance of 63-19 (001.M31) - The Imperial Compliance action of the world codified as Sixty-Three Nineteen (63-19) took place in the 203rd year of the Great Crusade. Forced off course by a Warp Storm, the Luna Wolves' 63rd Expeditionary Fleet discovered a system of 9 planets orbiting a yellow sun quite by accident. After entering the system they were contacted by a technologically-advanced human society based on the third planet. This world was ruled by a self-appointed "Emperor of Mankind" who claimed to be the predestined ruler of all the scattered remnants of humanity across the galaxy. He invited a delegation from the Imperial fleet to treat and pay fealty to him. The Warmaster sent his most favoured commander, Captain Hastur Sejanus and his Glory Squad to meet with this supposed "Emperor". Though initial negotiations appeared to proceed smoothly, they irrevocably broke down when the Astartes Captain dared to suggest that there was another, true Emperor of Mankind. Perceived as an insult, Captain Sejanus and his men were taken by surprise during a diplomatic parley and cut down. The death of Horus' favourite son and Mournival member would open an emotional chink in the Primarch's psyche that would later be exploited by First Chaplain Erebus of the Word Bearers Legion upon the Feral World of Davin during Horus' corruption by Chaos in the Temple of the Serpent Lodge. Though intensely grieved by Sejanus' death, Horus miraculously did not order an immediate retaliatory strike. Instead, he mobilised an Astartes "speartip" unit to stand by and prepare for a planetary assault. Horus then attempted to negotiate a second time by despatching Maloghurst and another contingent of Luna Wolves, but this mission also ended in disaster when Maloghurst's Stormbird was shot down and presumed lost. A great fleet of over 600 warships rose up from the planet's atmosphere to meet the 63rd Expeditionary Fleet, throwing down a challenge. The Warmaster responded in kind. The great naval battle that ensued is not recorded in detail in the existing Imperial records of this time, but eventually the Imperial fleet ultimately prevailed. The massive ground assault spearheaded by the Luna Wolves was led by First Captain Ezekyle Abaddon, as well as a half-dozen Titans which provided ground support while Assault Craft provided close-air support. The Luna Wolves were eventually able to close and penetrate the capital city's defences. The Luna Wolves fought their way inside the Imperial Palace until they came face-to-face with the supposed "Emperor". The false Emperor offered to surrender to the Imperial forces, but only to their overall acting commander, not his subordinate captains. The request was transmitted to the fleet, but Captain Garviel Loken of the 10th Company quickly realised that this was merely a ruse to draw Horus down to the Throne Room to be assassinated. 1st Company Captain Kalus Ekaddon, commander of the Catulan Reaver Squad, swiftly killed the man he believed to be the false Emperor. Then the true false Emperor revealed himself, striking with deadly force against those Luna Wolves that were present, and nearly succeeded in neutralising both Loken, Ekaddon and the other members of the Catulan Squad. He was only stopped by the timely intervention of the Luna Wolves' Primarch, as Horus teleported directly into the Throne Room and slew the false Emperor with a single, well-aimed Combi-Bolter shot to the head. The main part of the campaign was concluded with the death of the false Emperor. With the death of their leader, the main resistance on 63-19 collapsed, although there were some elements of the world's military forces that continued to wage a guerrilla war around the planet as well as three other worlds within the system. These resistance elements were eventually expunged through the efforts of the 63rd Expedition's attached Byzant Janizars Imperial Army regiment over the next few months. The last pocket of serious resistance to Imperial Compliance occurred in the Whisperhead Mountains located in the southern hemisphere. This last pocket of resistance would eventually be excised by Captain Garviel Loken's 10th Company over a period of three months. These hold-outs made their final stand within a formidable fortress carved out of the rock of one of the range's highest peaks. When the 10th Company fought their way inside the mountain fortress they discovered what appeared to be several primitive religious fanes or shrines. The Luna Wolves presumed that they were somehow connected to this region's superstitious worship of a being referred to as Samus. This being turned out to be a minor daemonic Warp-entity who had dwelled on and interacted with the inhabitants of 63-19 for many millennia. During the ensuing battle Samus possessed the body of one of the 10th Company's sergeants and was able to eliminate over a dozen Astartes and a number of Remembrancers that had accompanied the Luna Wolves before being cut down by the combined Bolter fire of Captain Loken and Sergeant Nero Vipus. The two Luna Wolves fired over 90 Bolter rounds into the possessed sergeant's body and then incinerated the remains with a Flamer. This was the first recorded incident in Imperial history of its military forces encountering the malefic powers of Chaos. The entire course of events was classified on the orders of the Warmaster, in order to hide the fact that an Astartes had turned on his fellow Battle-Brothers and that it was possible for the supposedly invincible Astartes to be corrupted by the malignant powers of Warp-entities, who were themselves a well-kept secret of the Imperium. Overall governorship of the world after it was brought into Imperial Compliance was given to General Rakris of the Byzant Janizars, while the adaptation of the cities and infrastructure of the world to Imperial standards was given over to Peeter Egon Momus. 63-19 was the first world that the newly-arrived Remembrancers of the 63rd Expedition added to their own records of the Luna Wolves' exploits.Compliance of 140-20 (Urisarach/"Murder") (ca. 001.M31) - The Death World of Urisarach (officially codified as One-Forty-Twenty but unofficially dubbed "Murder" by the Astartes who fought there) was the twentieth world encountered by the 140th Expeditionary Fleet, a contingent of the IXth Legiones Astartes, the Blood Angels, commanded by Captain Khitas Frome. Unable to translate the warnings from the orbiting satellite beacons placed in orbit of the world by the advanced human civilisation known as the Interex that warned approaching starships to stay away from Urisarach as a dangerous xenos species had been quarantined there, Captain Frome ordered his fleet's entire contingent of three companies of Space Marines to begin landing operations to investigate and bring the planet into Imperial Compliance. Due to the extreme atmospheric turbulence present on the world, all of the Blood Angels' assault craft attempting to land on the planet became scattered and were thrown far off-course, leaving the Imperial landing parties isolated from one another. The turbulent atmosphere also affected Vox (radio) communications and made it difficult for the Imperial forces to coordinate their movements. Ground teams soon started sending garbled transmissions to the fleet's vessels in orbit, reporting that the planet was inhabited by an extremely hostile intelligent arachnoid species, later dubbed the Megarachnids. The Megarachnids were an old enemy of the Interex civilisation, who had exiled the surviving members of the species to the world they called Urisarach as an act of mercy rather than committing xenocide as was standard policy for the Imperium. The Interex stripped the Megarachnids of their interstellar travel capabilities. To keep the aliens isolated on their new homeworld, the Interex constructed weather control devices that created powerful atmospheric disturbances and interfered with radio communications in the shape of large "trees" across the planet to deter vessels from landing on the Death World. As reports of horrific combat from the surface continued, the xenos were described as too numerous and formidable to defeat without reinforcements. Not long afterwards, the Blood Angels made urgent distress calls requesting immediate reinforcements and extraction. The last transmission received by the fleet of the 140th Expedition came from Captain Khitas Frome himself, who noted through clenched teeth, "This. World. Is. Murder." This name stuck, becoming the Imperium's informal appellation for Urisarach. A company of Astartes from the IIIrd Legion, the Emperor's Children, arrived in response to the Blood Angels' distress calls. They made the same mistakes during the initial assault as the Blood Angels, and their landing parties were scattered by the planet's powerful atmospheric disturbances. The company took heavy casualties but just as the Emperor's Children were about to be overwhelmed, a relief force of newly-arrived Luna Wolves Astartes from the Warmaster Horus' own 63rd Expeditionary Fleet began to land through the breach in the atmosphere. The Megarachnids assaulting the Emperor's Children were scattered and a full-scale Space Marine assault on the hostile xenos of Murder began in earnest. Ten companies of Luna Wolves, the remnants of the Emperor's Children's company, tens of thousands of Imperial soldiers drawn from the Imperial Army's Byzant Janizars, and several Legio Mortis Titans proceeded to level entire swathes of the grass stalk forests and destroy every one of the atmosphere-altering "trees" they encountered, which steadily eroded Murder's atmospheric barrier. The Warmaster Horus, who commanded the Imperial assault from his flagship Vengeful Spirit in orbit, was very pleased with the progress being made. Some consideration had been paid to initiating a withdrawal from Murder now that a proper landing zone was available to allow an easy extraction of the troops, when an unexpected visitor suddenly arrived. The Primarch Sanguinius had come to Murder to inspect the dead of his original Blood Angels landing force that had been wiped out early in the campaign. With tears in his eyes Sanguinius asked his brother Horus if he would join him in a campaign of vengeance against the foul xenos. The Warmaster replied: "Yes, let us murder Murder." Adding 5 companies of Blood Angels to the Imperial invasion force, Sanguinius fought alongside the Warmaster against the aliens. Thousands of Megarachnids poured out of the forests and canyons of Murder in an endless wave. Despite never retreating from the Imperial assault, the Megarachnids only continued to lose ground. By the sixth month of the campaign it seemed the Megarachnids would soon face extinction, when a fleet deployed by the Interex arrived in-system to determine who had assaulted the Megarachnids' reservation world. Finding contact with the highly-advanced humans of the Interex to be a more pressing issue that needed to be dealt with, the Warmaster ended the campaign against the xenos of Murder. The Megarachnids had been saved from extinction for a second time by their old enemy. Imperial records do not indicate the final fate of this savage species once the Horus Heresy began.Interex Compliance (ca. 002.M31) - The Interex were a highly advanced civilisation of humans that maintained a close alliance with various xenos races, including the ape-like Kinebrach. In many ways their technology was even more highly advanced than the technology employed by the Imperium at its height. Their world of Xenobia was first encountered by the 63rd Expeditionary Fleet during the Great Crusade. The Interex were devoted to fighting the menace of Chaos (referred to by them as "Kaos") and were therefore highly suspicious of the Imperium's intentions, as they believed that the interlopers from Terra might be servants of the Ruinous Powers. While Horus and his Mournival were treating with the leaders of the Interex, First Chaplain Erebus of the Word Bearers, who had been accompanying the Warmaster as part of his entourage and who was already a secret follower of the Chaos Gods like most members of his XVIIth Legion, infiltrated the Hall of Devices on Xenobia, a museum that contained various artefacts and weapons drawn from the history of the Interex and their allied alien species. His objective was to steal a highly valuable and deadly Kinebrach blade known as an Anathame, a Chaotic artefact sacred to the Plague God Nurgle. After claiming the blade, Erebus rigged the building to explode to make good his escape. Feeling betrayed by the Imperials, who they took for agents of Chaos for stealing a known Chaotic artefact, the Interex's troops immediately attacked the bewildered forces of Horus, sparking a deadly confrontation. The Warmaster was evacuated off-planet by his Astartes as the Luna Wolves unleashed their full might upon the Interex. The Anathame would later play a pivotal role in the corruption of Horus by the Dark Gods upon Davin's moon. The Interex were later destroyed by an Imperial campaign and all of their worlds were brought into Imperial Compliance.Battle of Davin's Moon (004.M31) - Sixty Terran years after the world of Davin was brought into Imperial Compliance, Horus was influenced by the Word Bearers' First Chaplain Erebus to return to the feral planet. He informed the Primarch that the Imperial Governor of the world, Eugen Temba, had turned from the light of the Emperor, and foresworn his oaths of fealty to the Imperium. According to Erebus, Temba had found the inhabitants of Davin's moon unwilling to comply with Imperial rule, and so the Planetary Governor had led an occupying force to the moon in an attempt to bring the wild tribes of the moon into the light of the Imperial Truth. But during the parley with the tribesmen, Temba and his men were struck down by a sorcerous attack that twisted their perceptions away from their loyalty to the Imperium, and they succumbed to the temptations of power and immortality offered by Chaos and more specifically by the Plague God Nurgle, who claimed Davin's moon -- and Temba -- for his own. Horus personally led a combined assault force of Luna Wolves, an Imperial Army regiment of Byzant Janizars, and a detachment of Titans of the Legio Mortis onto the moon's surface. They soon discovered the wreck of Temba's flagship, the Glory of Terra, which was now a ruined derelict. The mass grave of rotting bodies of the Imperial Army garrison left on Davin were found in the nearby swamp, wearing the remnants of the uniforms of the 63rd Expeditionary Force. They seemed to confirm that Temba and all his men had perished, but this was not the case. The corpses of the Imperial Army troops were reanimated through the power of Nurgle as Plague Zombies that emerged from the swamps and attacked the Imperial forces en masse. The Luna Wolves and Byzant Janizars cut down the reanimated corpses. After this confrontation, the Warmaster led a speartip assault of Astartes into the derelict flagship. The bloated, mutant form of the Nurgle-corrupted Imperial Governor was discovered deep within the rotting vessel by Captain Verulam Moy of the 19th Company. Temba attempted to convert the Luna Wolves captain to Chaos, but Moy refused, and so the corrupted Planetary Governor cut him down. Horus arrived shortly thereafter to confront the Chaos-corrupted Temba, whose long-deceased body was now grossly enlarged, swollen with the corpulent putrescence of Nurgle. During their confrontation, the Warmaster discovered that Temba's corrupted form was immune to most forms of conventional injury. Horus also noted that Temba seemed to posses preternatural swiftness for a being so bloated and bulky, as well as formidable skill in swordsmanship. Horus fought like never before, his every move needed to parry and defend. Eugan Temba had never been a swordsman, so where his sudden, horrifying skill came from Horus had no idea. This was most likely due to Temba being armed with the stolen Kinebrach Anathame, the xenos chaotic weapon that had been secretly stolen only scant weeks earlier from the Interex's Hall of Devices on Xenobia by the scheming Word Bearers First Chaplain Erebus. The Anathame was a tailored weapon, a blade of sentient metal dedicated to Nurgle that had been crafted by the Kinebrach metallurgists, using a technique now utterly forbidden by the Kinebrach's Interex allies. When such a blade was selected for use against a specific target, it became that target's nemesis, utterly inimical to the very molecular being of the chosen target. During the vicious battle, Temba stabbed the fell blade into the Warmaster's shoulder where his Power Armour had been torn away. Though in agony, Horus managed to finally subdue his foe and mortally wound him. As the corrupting power of Nurgle fled his ravaged and decaying body, Temba was wracked with guilt over what he had done. Before dying, he attempted to warn Horus against the power of the entities that lived in the Warp. Temba prophesised that only Horus could avert a grim future of never-ending war, where the Emperor was trapped in living death and Mankind was held in bondage to a nightmarish hell of bureaucracy and superstition. The spark of life finally fled Eugen Temba and he died, his soul consumed by the Warp. The wounded Horus was found by his Astartes and taken back to his flagship in orbit of Davin. Soon the Warmaster fell ill from the effects of the Anathame and was struck down by a mysterious malady sufficiently virulent to affect even his superhumanly resilient immune system. His mysterious illness was even beyond the skills of the Legion's Apothecaries to cure, and so, in desperation, Horus was brought to the surface of Davin to be "healed" in the Temple of the Serpent Lodge. First Chaplain Erebus had convinced the Sons of Horus to bring their Primarch to the Davinite priests, in direct violation of the Imperial Truth. The secret sect on Davin was really a Chaos Cult, and using sorcery (which had been outlawed by the Emperor at Nikaea) the cultists managed to warp the mind of the Warmaster against the Emperor by playing on the seed of jealousy and resentment that he felt for his father after the Emperor had left the Great Crusade behind to return to Terra. Magnus the Red, the Primarch of the Thousand Sons Legion, used his own potent command of sorcery to intervene and unmask Erebus, revealing his manipulations, but Horus' corruption by the power of Chaos Undivided could not be stopped as he gave in to his feelings of jealousy, egotism and bitterness. The Warmaster emerged from the Temple of the Serpent Lodge fully healed, but subtly changed in both mind and body, as he was now infused with the power of Chaos. Once Horus fully recovered, he finally took up the Emperor's offer to rename the Luna Wolves after himself as the Sons of Horus. He then schemed with the Astartes of his Legion's Warrior Lodge, aided and abetted by Erebus, to overthrow the Emperor and purge the XVIth Legion of its remaining Loyalist elements. Horus intended to unleash the greatest betrayal in human history in pursuit of his own mad ambition.Destruction of the Auretian Technocracy (004.M31) - Shortly after Horus' miraculous recovery on the Feral World of Davin, the newly renamed Sons of Horus encountered the human civilisation of the Auretian Technocracy on the world of Aureus during the Great Crusade. This human society had been founded during Mankind's early exploration of the stars during the Dark Age of Technology and had evolved along lines very similar to that of the Imperium, and more particularly to that of the Mechanicus of Mars. Horus and a contingent of Sons of Horus Astartes met with the Technocracy's leader, the Fabricator Consul, who represented the human government in its diplomatic talks with the Imperium. During their initial discussion aboard the landing bay of the Vengeful Spirit, Horus learned that the Auretian Technocracy made use of highly-coveted, lost Standard Template Construct (STC) technology. Upon learning this, the Warmaster turned his Combi-Bolter upon the Fabricator Consul and summarily executed him. He then ordered his men to annihilate the Fabricator Consul's personal guard who were known as the Brotherhood and who made use of Power Armour and weapons very similar to those of the Space Marines. Unknown to most of the Astartes within the Legion, the rot of corruption had begun to spread throughout the Legion shortly after Horus made his dark bargain with the Ruinous Powers. The official explanation for the Sons of Horus Legion's grievous actions against the Technocracy stated that the staff brought by the Fabricator Consul aboard the XVIth Legion's flagship possessed a weapon which he planned to use to assassinate the Warmaster. This prompted the resulting conflict with the Auretian Technocracy which lasted for over six bloody months. The World Eaters fought alongside the Sons of Horus on the Technocracy's homeworld of Aureus, and their Primarch Angron personally lead the final Imperial assault on the Iron Citadel held by the Brotherhood of the Auretian Technocracy. When the blood-maddened warriors of the World Eaters' Assault Companies stormed a breach in the walls, the Brotherhood detonated explosive charges that buried the warriors under thousands of tonnes of rubble. Angron tore his way free and butchered the remaining warriors of the Brotherhood with his monstrous chain-glaive. Ephraim Guardia, the Senior Preceptor of the Brotherhood Chapter Command and Castellan of the Iron Citadel, died in the first seconds of Angron's attack. The campaign had been a brutal one, as the Brotherhood made use of highly advanced power armoured suits similar to those employed by Legiones Astartes, but they were eventually defeated and their technology was requisitioned by the XVIth Legion. Horus would use the seized Auretian STC databases to entice a faction of the Adeptus Mechanicus to turn against the Emperor and join his rebellion. These Traitors would eventually form the core of what became the Dark Mechanicus and their treachery would unleash the terrible civil war within the Mechanicus that became known as the Schism of Mars.Cleansing of Ariggata (004.M31) - This was an Imperial Compliance action that was carried out jointly by the Luna Wolves, the Ultramarines and the World Eaters Legions against the world of Ariggata. A technologically advanced world, Ariggata had been isolated from the rest of humanity for many centuries, and when Imperial envoys arrived bearing word of the Emperor and the Imperial Truth, they were executed in a bloody gesture of independence. The military might of Ariggata was formidable, and thus the honour of its pacification fell to the Warmaster Horus and two other Space Marine Legions under his command. Most of the planet was quickly conquered, except for the massive fortress within which most of the leaders of the planet cowered. Eager to be on his way, Horus commanded Angron, the Primarch of the World Eaters, to take back the citadel and kill only the leaders. Eagerly, Angron led the assault. However, the fortress was heavily defended and the casualties were horrendous, a dozen World Eaters falling for a meter of land. Eventually, a ramp of corpses led up to a single breach in the wall, and the Astartes of the World Eaters Legion plunged in. Filled with rage over their fallen brothers, they were merciless. By the time the Ultramarines arrived, the battle was all but over. The inside of the fortress was filled with the dismembered and mangled corpses of the defenders, for not one soul had been spared the vengeful fury of the World Eaters. It was an absolute slaughter, the fortress having been transformed into an abattoir of human blood. The Ultramarines were disgusted by this savage behaviour and reported the World Eaters' growing barbarism to the Emperor. But Horus, already corrupted by the tempations of Chaos, knew that the World Eaters' savagery would make service to Khorne a good fit for the Legion -- and particularly for its rage-fueled Primarch.Istvaan III Atrocity (005.M31) - The Imperial Planetary Governor of Istvaan III, Vardus Praal, had been corrupted by the Chaos God Slaanesh whose cultists had long been active on the world even before it had been conquered by the Imperium. Praal had declared his independence from the Imperium, and had begun to practice forbidden Slaaneshi sorcery, so the Council of Terra charged Horus with the retaking of that world, primarily its capital, the Choral City. This order merely furthered Horus' plan to overthrow the Emperor. Although the four Legions under his direct command -- the Sons of Horus, the World Eaters, the Death Guard and the Emperor's Children -- had already turned Traitor and pledged themselves to Chaos, there were still some Loyalist elements within each of these Legions that approximated one-third of each force; many of these warriors were Terran-born Space Marines who had been directly recruited into the Astartes Legions by the Emperor Himself before being reunited with their Primarchs during the Great Crusade. Horus, under the guise of putting down the rebellion against Imperial Compliance on the world of Istvaan III, amassed his troops in the Istvaan System. Horus had a plan by which he would destroy all of the remaining Loyalist elements of the Legions under his command. After a lengthy bombardment of Istvaan III, Horus dispatched all of the known Loyalist Astartes down to the planet, under the pretence of bringing it back into the Imperium. At the moment of victory and the capture of the Choral City, the planetary capital of Istvaan III, these Astartes were betrayed when a cascade of terrible Life-Eater virus-bombs fell onto the world, launched by the Warmaster's orbiting fleet, unleasing the event known later as the Istvaan III Atrocity. Captain Saul Tarvitz of the Emperor's Children, however, was aboard his Legion's flagship Andronius and discovered the plot to wipe out the Loyalist Astartes of the Traitor Legions. He was able, with help from Battle-Captain Nathaniel Garro of the Death Guard who was in command of the Death Guard frigate Eisenstein, to reach the surface of Istvaan III despite pursuit and warn the Loyalist Space Marines of all four Legions he could find of their impending doom. Those that heard or passed on Tarvitz' warning took shelter before the virus-bombs struck. The civilian population of Istvaan III received no such protection: 12 billion people died almost at once as the lethal flesh-dissolving virus called the Life-Eater carried by the bombs infected every living thing on the planet. The psychic shock of so many deaths at one time shrieked through the Warp, briefly obscuring even the glowing beacon of the Astronomican. The Primarch of the World Eaters, Angron, realising that the virus-bombs had not been fully effective at eliminating all the Loyalists, flew into a rage and hurled himself at the planet at the head of 50 companies of World Eaters Traitor Marines. Discarding tactics and strategy, the World Eaters Traitors worked themselves into a frenzy of mindless butchery fed by their growing allegiance to the Blood God Khorne. Horus was furious with Angron for delaying his plans, but Horus sought to turn the delay into a victory and was obliged to reinforce Angron with troops from the Sons of Horus, the Death Guard, and the Emperor's Children. Fortunately, a contingent of Loyalists led by Battle-Captain Garro escaped Istvaan III aboard the damaged Imperial frigate Eisenstein and fled to Terra to warn the Emperor that Horus had turned Traitor. On Istvaan III, the remaining Loyalists, under the command of Captains Tarvitz, Garviel Loken and Tarik Torgaddon, another Loyalist member of the Sons of Horus, fought bravely against their own traitorous brethren. Yet, despite some early successes that delayed Horus' plans for three full months while the battle on Istvaan III played out, their cause was ultimately doomed by their lack of air support and Titan firepower. During the battle the Sons of Horus Captains Ezekyle Abaddon and Horus Aximand were sent to confront their former Mournival brothers, Loken and Torgaddon. Horus Aximand beheaded Torgaddon, but Abaddon failed to kill Loken when the building they were in collapsed. Loken survived and witnessed the final orbital bombardment of Istvaan III that ended the Loyalists' desperate defence. To prove his worth and loyalty to Lord Commander Eidolon of the Emperor's Children -- and thus to his Primarch, Fulgrim -- Captain Lucius of the 13th Company of the Emperor's Children, the future Champion of Slaanesh known as Lucius the Eternal, turned against the Loyalists that he had fought beside because of his prior friendship with Saul Tarvitz. Lucius slew many of them personally, an act for which he was then accepted back into the Emperor's Children Legion on the side of the Traitors. In the end, the Loyalists retreated to their last bastion of defence, only a few hundred of their number remaining. Finally, tired of the conflict, Horus ordered his men to withdraw, and then had the remains of the Choral City bombarded into dust for a final time from orbit.Drop Site Massacre of Istvaan V (566.006.M31) - The world of Istvaan V was the location of the infamous Drop Site Massacre where the Traitor Legions of the Warmaster Horus redeployed following the virus-bombing of the Traitor Legions' own Loyalist members at Istvaan III at the start of the Horus Heresy. Upon learning of the terrible atrocity Horus had committed, the Emperor deployed seven Loyalist Legions of Space Marines to bring Horus to account for his actions. The Iron Hands, Salamanders and Raven Guard made up the first wave of the attack, but were pushed back by the superior tactics of Horus' maddened Chaos Space Marines. During the course of the first wave of the attack, the Sons of Horus contingent fought on the defensive, limiting themselves to the core and most heavily defended bastions, and driving the Imperial Army before them into the Loyalists' guns. There was, however, one notable exception to this; their Reaver and Assault companies who deployed to counter the strike units of the Raven Guard in the maze of ravines and rock falls that flanked the walls of the Urgall Depression. The Loyalist reserves were called in during the second attack wave, but the four Space Marine Legions comprising them -- the Iron Warriors, the Alpha Legion, the Word Bearers and the Night Lords -- had also secretly betrayed the Emperor and were prepared to follow Horus and swear themselves to Chaos. Once the tide of the battle turned, the Sons of Horus attacked in force against the reeling and wounded Loyalists, with Horus himself taking to the field to lead them. The three Loyalist Legions were almost annihilated in the resulting crossfire but several thousand survivors from each Legion managed to escape off-world, though they were too decimated to play much of a further role in the defence of the Imperium from Horus' betrayal. The ensuing civil war pitched the whole Imperium into anarchy and chaos. It was not only the Legions aligned to Horus that rebelled, for the Warrior Lodges and the taint in general had spread far and wide by the time of the Drop Site Massacre. The Imperial Army was split almost in half, regiment fighting regiment and fleet fighting fleet. The Titan Legions of the Mechanicus, were equally affected, and soon fully half of the Emperor's hosts were engaged in bitter conflict with the other. Barely a single world in the Imperium was untouched by a war that lasted for seven standard years and cost countless billions of lives before finally culminating in Horus' assault on Terra itself.The Manachean War and the Dark Compliances (007-009.M31) - His treachery revealed at last, the Warmaster began his relentless advance on Terra, forcing his Dark Compliance of countless regions across the northern Imperium to provide his forces with a resource base to fight what would now become a protracted and relentless war. Foremost among his targets were the Manachean Commonwealth, the Coronid Deeps and their surrounding regions, where a particularly savage campaign was conducted by the Sons of Horus and Death Guard which brought the economically vital worlds of the Manachean Commonwealth to fuel the Traitors' cause. This wider campaign also placed the fleet anchorage of Port Maw under the Warmaster's talon and saw the stubbornly Loyalist Forge Worlds of Lucius and Mezoa isolated and besieged, while the Traitor-aligned Forge World of Cyclothrathe began to carve out its own pocket empire in the region.The Burning of Ohmn-Mat (008.M31) - The Forge World of Ohmn-Mat in the Ultima Segmentum fell into a state of civil war as its Synod Magos were split in their support for Loyalist and Traitor causes, drawing in contingents of Sons of Horus Dark Compliance forces and Iron Hands Istvaan survivors as the conflict escalated. Ohmn-Mat was destroyed in the conflagration and its fires still rage till the present.The Dagonet Incident (008.M31) - The hidden clade-masters of Terra, with the direct approval of Malcador the Sigillite, despatched their most potent assassins as the first Execution Force to the recently fallen world of Dagonet in an attempt to strike down the Warmaster. They were unsuccessful, but from their failure Terra learned much of the new and dreadful powers wielded by its foe.Second Battle of Paramar (008 or 011.M31) - The Sons of Horus provided a large garrison force alongside the Word Bearers and elements of the Dark Mechanicum's Traitor Titan Legions that defended the strategic world of Paramar V from a Loyalist attempt to retake the planet from Traitor forces during the Second Battle of Paramar.The Battle of Arissak (009.M31) - Having pursued the numerous attack cells made up of Iron Hands, Salamanders and Raven Guard survivors of Istvaan V, Captain Tybalt Marr of the Sons of Horus finally brought them to battle, destroying the massed fleet of Shadrak Meduson's so-called "Shattered Legions" force at Arissak.Destruction of Dwell (009.M31) - Horus arrived upon the world of Dwell, a world settled during the Dark Age of Technology by settlers from the nearby Knight World of Molech. The Warmaster was intent upon utilising the ancient repository on Dwell that contained information that would lead him in search of the Emperor's power back to Molech, where he had unknowingly taken part in that planet's Imperial Compliance campaign decades earlier, and had his memories suppressed by the Emperor. Shortly after the infamous campaign on Istvaan V, the Sons of Horus were also forced to recoup their losses. Another change, forced on the XVIth Legion, was the loss of the Mournival. With the deaths of two of their former brothers, the Loyalists Garviel Loken and Tarik Torgaddon on Istvaan III, there were openings available to those that might be deemed worthy. Captain Horus Aximand approached First Captain Ezekyle Abaddon with the proposition to select two new members to fill the vacancies. They argued over who they thought would be worthy to join a newly reconstituted Mournival. After much debate, they both finally came to an accord, agreeing on suitable replacements. These would be Falkus Kibre, the commander of the Catulan Reaver Squad and Sergeant Grael Noctua. With rumours of the infamy of Horus' actions in the Istvaan System spreading across the nearby systems, a series of ferocious repercussive combats had flared through the Momed, Instar and Oqueth Sectors. The instigator was a leader of the Iron Hands Legion's "Iron Tenth", a warleader of the Sorrgol Clan named Shadrak Meduson. He had marshalled the Loyalists against the approaching Traitors of the 63rd Expeditionary Fleet. The Iron Hands warleader and his formations had come too late to stand with his Primarch Ferrus Manus at Istvaan V. He had gathered 58 full battalions of the Imperial Army about him -- warhosts from the Momed Voidhives, along with a flotilla of siege hulks from Nahan Instar, a half-broken cadre of Salamanders Astartes, some Mechanicus claves, and a White Scars raid-force rerouted from a return voyage to the Chondax war front. The world of Dwell, with its fortified cities, orbital batteries, ship schools, and eight million pinnacle-grade fighting men, would be the cornerstone of Meduson's defensive line. The Iron Hands warleader positioned himself at the Mausolytic Precinct which was situated on a high plateau overlooking Tyjun and the Sea of Enna. The Sons of Horus launched a planetary assault against Dwell, butchering the regular human Loyalist defenders, but were caught by surprise when they encountered the ad hoc Loyalist Astartes force that had secretly fortified the system. When the Sons of Horus assault units breached the fortifications, Horus Aximand slew Meduson's second-in-command, the Iron Hands Lieutenant Bion Henricos, but "Little Horus" was then attacked by a White Scars kill-formation disguised as statues. Meduson's co-commander, Captain Hibou Khan of the White Scars, led the Loyalist counterattack against the Traitors, but they were quickly driven off with the arrival of Sons of Horus reinforcements. One of the White Scars managed to gravely wound Aximand by slicing off his face. The XVIth Legion's Apothecaries managed to reattach Aximand's severed face, but the muscle grafting left a wicked scar which made him look more brutal. It set the character of the face differently, altered the seating of the muscles so that his appearance now matched the growing corruption within his heart. Somehow, the wrongness, the imperfection, made him seem even more like Horus, not less. Having escaped death at Arissak, one of Shadrak Meduson's surviving Shattered Legion attack cells launched a daring assassination attempt on Warmaster Horus at Dwell. With his brother-Primarchs Fulgrim and Mortarion at his side, Horus prevailed, but having had the true threat revealed to him, he granted Tybalt Marr permission to take any action he deemed appropriate to eradicate the so-called "Shattered Legions".Battle of Molech (009.M31) - Horus led both the Sons of Horus and the Death Guard Legions in the invasion of the Fortress World of Molech. Having recovered some of his memories in regards to the earlier campaign that took place decades earlier, Horus uncovered the truth about the hidden subterranean Warp portal that led into the Realm of Chaos. Wanting this power for himself, he launched a massive strike on the unsuspecting world. During the height of the conflict, the Knight House Devine turned against the Imperium and joined the invading forces, betraying the defenders to their deaths. A force of the elite Knights-Errant, a secretly founded Order of Loyalist agents, was dispatched to Molech by Malcador the Sigillite to prepare the way for a direct assault by the Space Wolves against the Warmaster's flagship. After his sojourn through the portal into the Realm of Chaos, and winning the full blessings of the Ruinous Powers, Horus was nigh unstoppable, and only a handful of Knights-Errant managed to effect their escape to bring news of his redoubled strength back to Terra.Siege of Terra (014.M31) - As the events of the Horus Heresy neared their tragic conclusion seven years after the fateful betrayal at Istvaan III, those Loyalist Legions not committed to the defence of Terra raced through the Warp, converging on the homeworld of Mankind. The Traitor Legions also massed above Terra to assault the Imperial Palace. The Siege of Terra was the final confrontation of the Horus Heresy that raged on Terra itself between the forces of Chaos led by the Warmaster Horus and the Loyalist armies of the Imperium of Man led by the Emperor of Mankind Himself. The Loyalist forces ultimately proved victorious in their defence of the Imperial Palace, though only just barely, and Horus was ultimately slain by the full psychic powers unleashed by the Emperor on the deck of his massive Battle Barge the Vengeful Spirit, though the Master of Mankind was mortally wounded and had to be interred within the cybernetic life support mechanisms of the advanced psychic augmentation technology known as the Golden Throne. The outcome of the Siege of Terra shaped the destiny of humanity for the next 10,000 standard years. The Traitor hosts began their fighting withdrawal, and in the anarchy and confusion Horus' body was recovered by his Legion from his flagship. Having fought their way clear of the Sol System the XVIth Legion fled for the Eye of Terror where the Sons of Horus established a world that was at once the tomb of their lost Primarch and a fortress from which they would launch further attacks both upon their fellow Traitor Legions and against the smouldering Imperium. Thus began the Long War of the Forces of Chaos to overthrow the Corpse Emperor. With Horus slain, First Captain Ezekyle Abaddon emerged as the Warmaster's heir, commanding both the Sons of Horus and what remained of the splintering Forces of Chaos. Soon known as Abaddon the Despoiler, he renamed the Sons of Horus the "Black Legion" and declares himself the new Warmaster of Chaos Undivided. Highly favoured by the Chaos Gods, Abaddon intends to complete the task begun by Horus and see the Emperor slain and the Imperium ground beneath the boots of the XVIth Legion.Slave Wars/The Legion War (Unknown Date.M31) - Using slaves captured from their campaigns against the Imperium during the Heresy, the XVIth Legion was able to build a massive fortress on the Daemon World of Maeleum and entombed the corpse of their slain Warmaster Horus within it. However, not long after, the Eye of Terror Slave Wars erupted and the Emperor's Children Legion launched a devastating surprise assault on Maeleum, devastating the Sons of Horus' fortress and stealing Horus' corpse in an attempt by the corrupted Apothecary Fabius Bile to clone the dead Warmaster of Chaos and restore the fortunes of the Forces of Chaos in the wake of the Imperium's victory. It was at this time that Abaddon the Despoiler returned to lead his forces to recover Horus' corpse. Following the successful defeat of the Emperor's Children and the shattering of that once-proud Space Marine Legion into gibbering, hedonistic warbands, the Sons of Horus recovered the corpse of their former leader. Abaddon returned it to Maeleum where he had it destroyed so that no further attempts to clone Horus could ever be attempted. At the same time, he came to the epiphany that Horus was dead because Horus had been a weak fool, unable to complete his task of slaying the Emperor and taking control of the galaxy in the name of the Dark Gods. Abaddon swore that he would succeed where Horus had failed in overthrowing the "Corpse-Emperor" and proclaimed himself the new Warmaster of Chaos. He had the Sons of Horus repaint their viridian Power Armour black, the colour of mourning and of vengeance, and cast-off the XVIth Legion's former moniker of the Sons of Horus. From then on, they became known as the Black Legion. The Black Legion then abandoned the ruins of the Sons of Horus' fortress and left Maeleum behind, choosing to become a fleet-based Legion with scattered holdings all across the Eye of Terror.The Black Legion Rises (Unknown Date.M31) - Ascending to dominion of the Sons of Horus, Abaddon embarks on a quest to slay the clones Fabius Bile has crafted from Horus' remains. Destroying the Primogenitor's hidden laboratories and the abominations he created, Abaddon leaves behind no trace of his gene-father. With the final and utter destruction of Horus, Abaddon renames his Legion the Black Legion.