Chaos Space Marines

A Chaos Space Marine, also sometimes called a Traitor Marine, is a former Loyalist Space Marine of the Imperium of Man who has chosen to betray the service of the Emperor of Mankind and dedicate his soul to the service of Chaos and its foul deities. Such corrupt Astartes normally belong to one of the 9 Traitor Legions that betrayed the Emperor during the ancient civil war called the Horus Heresy more than 10,000 standard years ago, while others come from Space Marine Chapters created long after the Heresy ended that have turned Renegade. Chaos can corrupt Astartes of any time and place just as its siren call leads many lesser men to their damnation.

During the Horus Heresy, the terrible Imperial civil war that pitted the Battle-Brothers of the 18 known Space Marine Legions against one another, there were two factions. These were the Loyalist Space Marines who continued to serve the Imperium and the Emperor of Mankind and the Chaos Space Marines of the Traitor Legions who betrayed the Emperor's trust and pledged their souls to the dark service of the 4 Ruinous Powers of Chaos. The Traitor Legions were led by the Warmaster Horus, once a Primarch of the Imperium and the Emperor's most trusted friend, son, and adviser before he was corrupted by the promises and lies of the Dark Gods and his own inner flaws.

The Traitor Legions were the most powerful component of the Forces of Chaos which fought during the Heresy, which also included the myriad daemons of the Warp, human Traitors from the Imperial Army, the Dark Mechanicus and Chaos Cultists drawn from across the galaxy. The flesh and Power Armour of Chaos Space Marines often warps and twists into new, darker and inhuman forms under the influence of the Chaos energies they are exposed to as their shapes morph to embody the corrupted Astartes' new allegiance. Chaos Space Marines fight for everything they were once forbidden to indulge in as the ascetic servants of the Emperor and the selfless guardians of Mankind. Pleasure, wealth, but above all else the power to rule their fellow men in the name of the Chaos Gods, is the driving ambition and goal of every Chaos Space Marine.

History
The Traitor Legions of the Chaos Space Marines represent 9 of the 20 original First Founding Legions of Space Marines who were created by the Emperor of Mankind from the genomes of his 20 Primarchs in the late 30th Millennium to fight the Great Crusade that forged the Imperium of Man. At this time Horus, the Warmaster of the Imperial forces and Primarch of the XVI Legion, the Luna Wolves, (which the Emperor allowed him to rename the Sons of Horus in his honour before the onset of the Horus Heresy to demonstrate his status as first-among-equals among the other Primarchs), was corrupted by Chaos and instigated the galaxy-wide Imperial civil war known as the Horus Heresy in his determination to replace the rule of the Emperor with his own.

After the death of Horus at the hands of the Emperor aboard his Battle Barge Vengeful Spirit during the Battle of Terra that ended the Horus Heresy, the remnants of the 9 Traitor Legions fled, along with the other Traitor Imperial forces that now served Chaos, into an area of the galaxy where the Warp bled into realspace, creating the permanent Warp Storm known as the Eye of Terror. Due to the nature of Chaos, and the temporal instability of the Warp, many of the very same Chaos Space Marines who revolted against the Emperor more than 10 millennia ago continue to fight against the Imperium today, having effectively been granted a tortured immortality by the will of the Ruinous Powers.

The Traitor Legions have kept their old names, with the exception of the Sons of Horus who were renamed the Black Legion by their new leader, Abaddon the Despoiler, once Horus' chief lieutenant and the First Captain of the Luna Wolves before he followed Horus into damnation. Besides Horus, 2 other Traitor Primarchs were killed during or shortly after the Heresy (Alpharius of the Alpha Legion and Konrad Curze of the Night Lords). The 6 surviving Traitor Primarchs have since been transformed into Daemon Princes by the Chaos Gods they serve. These daemonic Primarchs rarely take part in the affairs of their Legions or are major players in the affairs of the galaxy. Four of the Traitor Legions have pledged a singular loyalty to one of the great Chaos Gods. while the others serve the interests of Chaos as a whole in the form of Chaos Undivided. Due to the nature of Chaos and those who choose to serve it, not long after the end of the Heresy the Traitor Legions, save for the Word Bearers, largely stopped operating as unified military organisation and instead devolved into a series of separate and often competing warbands. The Traitor Marines who command these warbands, all potent Chaos Champions, sought their own personal glorification and the eventual opportunity to become Daemon Princes in their own right by earning victories in the cause of Chaos.

Due to the fractious nature of the Dark Gods, the warbands in service to a particular Ruinous Power often view other Traitor Marine warbands who serve its patron's rival deity as even more appropriate targets for their wrath than the servants of the Emperor. With such an attitude prevailing among the corrupted Astartes, it has often proven impossible for the Traitor Legions to present a united front against the Imperium since the death of Horus, once reason why they have never enjoyed a similar series of military successes over the past 10 millennia. The closest thing to unity that has appeared amongst the Traitor Legions and other Chaos Space Marines was when Abaddon the Despoiler, the successor of Horus as the Warmaster of the Black Legion, launched one of his periodic Black Crusades into Imperial space under the banner of Chaos Undivided, which is a temporary period of unity amongst all the Forces of Chaos when they seek to overwhelm the Imperium's defenses surrounding the Eye of Terror and drive on Terra once more. Abaddon is the only Champion of Chaos since Horus himself who is able to command, however begrudgingly and briefly, the loyalty of all 9 Traitor Legions, and he has led 13 Black Crusades out of the Eye of Terror against the Imperium of Man. The latest, the 13th Black Crusade, was launched in 999.M41 and has proven the most successful for the Forces of Chaos since the Horus Heresy. The Chaotic troops were able to seize a foothold on the surface of the Fortress World of Cadia, though the Imperial Navy has so far managed to blockade Abaddon's Traitor Marines and the other Forces of Chaos from breaking out into the Cadian Gate, the only clear pathway through the Warp from the Eye of Terror into open Imperial space. Should the Chaotics manage to eventually break out of the Imperial Navy's stranglehold, the Chaos Space Marines may at last, after 10,000 years, bring down the realm of the Corpse Emperor and gain their vengeance for long millennia of exile. Then the galaxy will tremble as the servants of the Dark Gods at last throw down the Corpse Emperor and claim the souls of Mankind for their own.

Chaos and Loyalist Space Marine Differences
All men of power can choose to devote their lives to the pursuit of great good or great harm to others, and the Space Marines are no different from other mortals in this respect. Genetically engineered as an adolescent to be a superhuman warrior, and armed and armoured with the Imperium's most advanced technology, a Space Marine is intended to serve as the ultimate defender of Mankind. Not only is his body protected against the weapons of his foes, but his mind has been toughened through the use of potent psycho-conditioning and indoctrination methods to expunge all fear, pain and temptation. To become an Astartes is to surrender one's own life and aspirations to the service of the Emperor and Mankind, and to wholly dedicate oneself to this singular purpose forever more. Those who live secure behind the shield of valour created by the Space Marines can never truly understand the true enormity of the sacrifice that the Astartes have made for their fellow men -- for they have sacrificed their own humanity in service of those they have sworn to protect.

When an Astartes falls from grace, he will fall further than other mortals. A lifetime dedicated to self-deprivation and selflessness is simply thrown aside and the Space Marine indulges his newfound independence in thought and deed to its fullest extent. Freed from the constraints of the discipline, traditions and responsibilities that define the Adeptus Astartes, a Chaos Space Marine can exercise his every whim, whether it be for bloodshed, mayhem, sensual pleasures long denied, ambition, love or simple vengeance. Given full reign to his long-supressed personal desires, his incredible physical powers and mental strength can be turned to the pursuit of the most malevolent acts, untrammeled by any sense of either mercy or guilt. When an Astartes' will finally breaks, the result is catastrophic as the whole edifice of his purpose and psyche tumble into an often violent maelstrom of unleashed and pent-up desire.

Having been created for combat, most Chaos Space Marines first turn to the only thing they have ever known -- the pursuit of war. Though their ideals and goals may have been cast aside, their superhuman bodies and tactical and strategic skills remain intact. Released from the confines of the need to follow orders and pursue missions prescribed by others, a Chaos Space Marine can become a cold and psychopathic killer without morals or restraint. He pursues this bloody life to its fullest extent, glorifying in the power of his genetically enhanced body and the ability it renders him to unleash death and misery upon those he once served.

Some Chaos Space Marines never grow past this point and remain bloodthirsty Renegades, corsairs and pirates for the rest of their long lives. Others, now free to explore the temptations of the galaxy all around them, reach out in all direction to widen their mental horizons and experiences. Once a subservient cog within their Legion or Chapter's machinery dedicated to the service of a distant Emperor, a Chaos Space Marine may come to relish the chance to be a master rather than a servant, enslaving nations and whole worlds into the service of himself and the Ruinous Powers. Other prefer to pursue other avenues, such as the study of once-illicit texts or a passion for technical or sorcerous knowledge forbidden to the servants of the Imperium. Some Chaos Space Marines prefer to inflict pleasure and pain upon themselves, pushing their bodies and minds to the limits of what they can withstand and beyond, desperate for a sensual reward that mortals, even Astartes, were never intended to experience.

To be a Chaos Space Marine is ultimately to feel a near god-like power over other beings, particularly one's fellow men. Having been freed for decades, if not centuries, from the experience of fear and now released from responsibility, a Chaos Space Marine does not dread either retribution or punishment for his deeds. For most Chaos Space Marines, all memories of their heroic pasts are soon lost amidst the rivers of blood and the ecstacies of new sensation, and any thoughts of the future are but half-imagined cravings for more...more power, more killing, more pleasure, more pain.

By dedicating himself body and soul to the Dark Gods, an Astartes not only finds a patron who approves and encourages his new life, but who will actually reward him the further down that path he walks. For one whose sole existence was once defined by the necessity of self-denial and utter obedience, the euphoria of this realisation of true freedom can be an even more potent intoxicant than the pride he once felt at being accepted as one of the Emperor's Space Marines.

It is this temptation that constantly beckons to all Loyalist Space Marines. They cannot claim to be ignorant of its existence, as the teachings of their Chapter and its Chaplains remind them daily of both their purpose and their duties. No Space Marine casually walks away from these once-welcome bonds, no matter what might occur in his life. For an Astartes to turn to the service of Chaos he must consciously make the choice to walk a radically different path, to chose profane freedom over righteous service. Once made, it is a decision that can never be recanted, for from the moment that a Space Marine renounces his service to the Emperor, he is truly lost and irrevocably damned.

The Chaos Space Marines have the same genetic origins as the Space Marines in the gene-seed created by the Emperor from the genomes of the 20 Primarchs, and thus have the same physical abilities as their uncorrupted counterparts. Due to their allegiance to Chaos, Veteran Chaos Space Marines often suffer from extreme mutations (or Chaotic "gifts" depending on the point of view). Traitor Marines are virtually immortal due to their sojourns within the Warp, and their millennia of experience afford them levels of tactical mastery and advanced battlefield skills that the much younger Loyalist Space Marines have not yet have earned.

Chaos Space Marines are equipped with the ancient patterns of Power Armour and weapons they had when they initially betrayed the Imperium at the start of the Horus Heresy, which are broadly the same as those used by the current Loyalist Space Marines (although some differences now exist with regard to Jump Packs, Power Armour appearance, etc). At present in the late 41st Millennium, some 10,000 standard years after the Horus Heresy, the Imperium of Man has made a few, mostly minuscule technological advancements, due to the recovery of certain Standard Template Construct (STC) technologies from the interstellar human civilisation that existed during the Dark Age of Technology, though in most ways the Imperium has either completely stagnated or even regressed from the technological level prevalent across the Imperium during the Great Crusade in the early 31st Millennium. Chaos Space Marines have far more limited access to the handful of new inventions that have appeared on the galactic scene in the last 10,000 years. In general, anything developed since the Heresy is unavailable to the Traitor Marines unless it has been captured or was already deployed among Space Marines who went Renegade in more recent centuries; for example, the Iron Warriors Traitor Legion is well-known for capturing and using more modern patterns of Imperial tanks and armoured vehicles. While Chaos Space Marines may possess older technology than their Loyalist counterparts, they compensate for this weakness through the ability to summon daemons from the Immaterium and make use of daemonic technology like daemon engines, as well as the unbridled power of arcane sorcery drawn from the Warp without fears of limitation or corruption.

Because the Chaos Space Marines have all dedicated their souls to Chaos, they are extremely fearful of death, knowing that their souls will ultimately be consumed by the Ruinous Powers, unless they can earn the rare promotion to become Daemon Princes in their own right. The Chaos Gods do not truly care for their Chaos Space Marine servants, any more than they do for any mortals who serve them. The Dark Gods would gladly see them tortured for all eternity within their realms in the Immaterium simply for their own pleasure. Worshipers of Khorne are cursed to feel eternal rage but denied the ability to slaughter, the children of Nurgle are forever consumed by despair and the wracking pains of a hideous death, those who serve Slaanesh as their patron will be tortured for the sheer pleasure of the Prince of Chaos until the end of time, and the servants of Tzeentch know only endless insanity as their souls constantly change in form and the knowledge of the universe they crave is forever placed just out of their reach. In theory, those souls who choose to serve Chaos Undivided are either shared or fought over by the Chaos Gods in the afterlife of the Immaterium.

Only the promise of eternal life as a Daemon Prince, a dubious honour earned through unbridled success in the service of Chaos, reassures those mortals who pledge their lives and souls to Chaos. This fear of death, however, does nothing to slow or halt the vicious might of the Chaos Space Marines, who are quite sure that the power they have received from the Chaos Gods in return for their souls will ultimately provide them with rule over their fellow men, as is the right of every Astartes. It will also provide the opportunity to earn the necessary glories required to appease the Dark Gods and claim the daemonic immortality they offer as ultimate reward.

Gods and Champions of Chaos
In the Immaterium, similar thoughts and emotions of the sentient beings of the galaxy join together like rivulets of water running down a cliffside. They form streams and flows of anguish and desire, pools of hatred and oceans of pride. For billions of standard years these tides and waves of psychic energy have flowed unceasingly through the Warp and such is their power that they eventually formed intelligent creatures hewed from the energy of the Empyrean. These instinctual, formles entities eventually gained rudimentary consciousness and the Chaos Gods were born -- great psychic presences composed of the best dreams and worst nightmares of the galaxy's mortals. As the sentient races of the galaxy prospered and grew, their hopes and dreams, their rage and conflicts and their loves and hatreds, all fed the growth of the Chaos Gods and nurtured their power. Eventually, the gods reached into the dreams of mortals to demand both their praise and their service.

A Chaos God can only increase its power through the collective actions and thoughts of the galaxy's mortals, regardless of their species of origin. Those that worship a Chaos God and behave in a way that feeds its psychic nature are rewarded with strange gifts, mutations, extraordinary psychic powers and potentially the greatest reward -- ascension as an immortal Daemon Prince. As the Chaos Gods battle one another within the Warp and the Realm of Chaos, so to do their followers wage war upon one another in the material universe. The victors of these battles earn more power for their masters, although the machinations and natures of the Chaos Gods are such that often a victory is unnecessary, merely the acts of sacrifice and battle in and of themselves.

When the devotees of Chaos die, their psychic energy, their souls in the Warp, do not fade away to an unknown destination, are not destroyed and are not devoured by daemons like the souls of others. Instead their souls are swallowed by the collective power of the gods, sustaining them and increasing the eternal power of Chaos.

Although untold billions of sentients worship the Chaos Gods under a myriad of different guises, names and aspects, for the majority of those who serve Chaos, the Dark Gods offer simply the chance for more power and wealth in a universe where such things are rarely easily attained. But there are those few men and women who dedicate their lives to becoming true warriors of the Chaos Gods. For these devotees, the allure of Chaos is even stronger. The Champions of Chaos have a deep, fervent belief in the Ruinous Powers and their committment is total: they swear themselves body and soul, in life and beyond, to Chaos.

Those who dedicate themselves to the service of Chaos are doomed to an all-or-nothign existence as Chaos Champions in the service of one of the Dark Gods or another, or even of Chaos Undivided. The reward for those who please their god is ultimate power; for those who fail it is only eternal oblivion. To achieve greatness in the eyes of their god, Chaos Champions will perform any act, no matter how immoral, insane or vile. A Champion of Chaos does not simply praise and venerate the Chaos Gods, he swears his life and soul to their service, bargainign his own being in exchange for power and the rewards of their patronage. Granted the forbidden knowledge and strength of Chaos, a Champion can lead armies, conquer whole worlds and achieve greatness and ultimately, immortality. At the same time, the gods who choose to favour this Champion can bring their influence to bear upon him, so that even as he furthers his own ambitions, he also furthers the dominance and plots of his patrons. Chaos Champions are the leaders of the Forces of Chaos and the majority of them are Chaos Space Marines, though some have far more mundane origins. It is a great irony that the same abilities that make Space Marines the greatest defenders of the Imperium are also extraordinary assets for those who would become the most potent warriors of the Chaos Gods.

The genetic alterations that create a Space Marine also make Astartes more resistant to the mutational affects of exposure to the energies of Chaos, which allows a Chaos Space Marine to better survive the attentions of his oft-capricious new patrons. Just as their bodies benefit from the changes wrought upon them by the ancient technologies pioneered by the Emperor, so too are the minds of Space Marines honed to an incredible focus and possessed of a potent force of will. These are qualities that stand a man in great stead if he wishes to become a Chaos Champion--those who lack a certain clarity of thought, who lack the mental steel required to be successful, will soon be engulfed and lost to the constant anarchy of service to Chaos or will be swiftly overthrown and slain by more ambitious and ruthless subordinates and comrades. Chaos cares little for loyalty -- power is given to those strong enough to claim its rewards.

Chaos Warbands
Save for a few Champions dedicated to the most pure service of Khorne, Chaos Champions do not live and fight alone. Other followers of Chaos are drawn to them, either through the will of the gods or through the draw of a Champion's own glory and reputation. These groups form the warbands of Chaos and they can vary in size from a handful of individuals to massive armies that rival an Imperial Guard regiment in size and power. The most successful Chaos Champions command vast armies of devoted warriors. For Chaos Space Marines these warbands are mostly composed of comrades they fought alongside in their Traitor Legions or their Renegade Chapter. Yet it is not uncommon for Renegades with very different histories to find a common caise in their service to the Ruinous Powers, as Chaos recognises neither hierarchy nor structure, only results.

These warbands compete with each other as much as they fight against xenos and the forces of the Imperium. Resources are precious and hard-won in the Eye of Terror and the Maelstrom and control of cities, continents and worlds is vital to the maintenance of power. Most valued over all other things is the favour of the Chaos Gods. Champions and their warbands must constantly prove their continued dedication to their patrons. The Chaos Gods are embodiments of the question: what have you done for me lately?

Champions earn rewards from their gods by destroying their patron's enemies and succeeding on obscure missions and quests. On the Daemon Worlds in the Eye of Terror, hundreds of warbands struggle in battle to best each other for possession of daemonic artefacts, ancient knowledge, weapons and war machines left over from the days of the Horus Heresy and from before the Fall of the Eldar. They are pitched into eternal conflict as sacrifices to their gods and to earn the power to summon daemons to their cause. When not battling one another, the warbands of Chaos Space Marines are a roving threat, for they are wandering bands of nomadic warriors intent only on slaughter and loot. From bases hidden in asteroid fields and upon the surfaces of deserted moons, aboard painstakingly maintained starships that date back to the Great Crusade, they watch and wait for their prey to appear, gathering strength wherever a new blow can be struck against the despised Imperium of Man and its hated Corpse Emperor.

Ascension
In the end, every Chaos Champion faces one of three fates. A life of constant warfare is a dangerous one and most will die upon the field of battle, forgotten by their god as just another failure but immortalised in legend by their remaining followers and comrades. These Champions are nothing more than blood-soaked sacrifices to Chaos, their goals and ambitions forever unfulfilled.

A Chaos Champion who survives the constant battles will slowly gain more and more favour from their chosen god. These gifts can come in many forms. Some Champions may be "sent" more followers. Those with a taste for such things might learn potent spells of psychic sorcery, while all Champions will eventually exhibit strange, inhuman powers. Most of the "gifts" offered by the Chaos Gods take the form of physical and genetic changes -- mutations. Some mutations are beneficial, some are harmless -- and others are downright debilitating.

Though such changes can make a Chaos Champion a fearsome warrior, he risks receiving so many such "gifts" and become so mutated, that he loses all control of himself and degenerates into the hideous creature known as a Chaos Spawn. Even the superhuman, genetically-engineered body of an Astartes can only withstand so much genetic corruption and can contain only so much unnatural power. When this limit is finally breached, the Space Marine or other Champion will be lost forever, transformed into a gibbering and mindless Chaos Spawn. Driven insane, Chaos Spawn are nothing more than mindless, howling monsters of tortured, mutated flesh. Most die quickly and painfully, their bodies ripped apart by cascading and uncontrollable mutations as the power of Chaos is made wholly manifest within them. Of those who do not die instantly upon surpassing the limit of the Chaos power that their bodies can withstand, some are abandoned by their warbands to wander the Daemon Worlds until they are slain, while others are kept as pets and war beasts by those who were once their followers.

But the third fate of a Chaos Champion is the reward to which all devotees of Chaos dedicate themselves: ascension to daemonhood. The Champion's ultimate reward is ascension to become a Daemon Prince of his patron god. His flesh is transformed into the immaterial substance of the Warp and his mortal life is entirely cast aside. A follower of Chaos who ascends to become a Daemon Prince is an immortal and all-powerful warrior who will serve his god for all eternity and never know death or fear again. Some Daemon Prince leave their mortal followers behind and join the nightmare hosts of the Daemons of Chaos to plague worlds across the gulfs of space and time as embodiments of the power of their gods. Others choose to remain the leaders of their warband, now granted an eternity to bask in the adoration of their minions and earn perhaps even greater power from the Dark Gods that they have served so well.

Chaos Space Marine Traitor Legions
Each of the 9 Astartes Traitor Legions fights using a different style of warfare that is defined by their Legion's culture and nature; also, 4 of the 9 -- the Emperor's Children, the World Eaters, the Thousand Sons and the Death Guard -- are dedicated specifically to the service of 1 of the 4 major Chaos Gods, Slaanesh, Khorne, Tzeentch and Nurgle, respectively. The other 5 Traitor Legions essentially serve the interests of all of the Ruinous Powers collectively in the form of Chaos Undivided.

The 9 Chaos Space Marine Traitor Legions are (in order of their Founding):

Renegade Space Marine Chapters
Through the passing of the centuries since the Horus Heresy, the Forces of Chaos have been further swelled by those Space Marines from the later Foundings who have turned from service to the Emperor of Mankind to pursue their own agendas. According to the current records of the Inquisition's Ordo Malleus, approximately 50 Loyalist Chapters or elements of Loyalist Chapters have turned Renegade in the ten millennia since the Horus Heresy. Examples include the Sons of Malice, the Damned Company of Lord Caustos, the Violators, the Thunder Barons, and the Astral Claws (known as the Red Corsairs since their rebellion against the Imperium during the Badab War). A more complete list can be found here.

Freed from the Imperial dogma and traditions of their Chapter, these so-called Renegade Space Marines fully indulge the needs of their superhuman bodies and their militant minds. They most often become corsairs, pirates and mercenaries, using their unparalleled combat skills to garner wealth and power for themselves, rising as tyrannical masters of pirate fleets and the masters of desolate frontier worlds. As they explore their new freedom from the discipline and strict purpose of the Adeptus Astartes, these Space Marines inevitably turn at some point to the Chaos Gods to gain more power to do as they will. From this point on, they are fated to walk the path of the Chaos Champion as much as any of the original Traitors of the Horus Heresy. These Renegades are hunted men -- loathed by all the other Space Marine Chapters, who consider it their foremost duty before the Emperor to destroy any Renegade Astartes lest their vile shame and dishonour leave a black stain upon all the Loyalist Space Marines who have never turned their face from the light of the Emperor or their duty to Mankind for their own selfish gain.

Though never equal in size or power to the original Astartes Legions, a modern Space Marine Chapter is a potent military force in its own right and when an entire Chapter turns Renegade it presents a grave threat to the Imperium. With all the resources of a Space Marine Chapter at their disposal, the Renegades of Chaos destroy Imperial armies, conquer Imperial worlds and despoil whole sectors of the Imperium. Such events warrant an extreme response from the Imperial forces, not to mention the other, Loyalist Space Marine Chapters. It is perhaps the greatest test of faith for a Space Marine to fight another Astartes and these internecine conflicts often have a terrible effect on other nearby Chapters. In these circumstances, such inter-Chapter wars tend to escalate quickly, engulfing many worlds with bloodshed. On Occasion, those forces sent to deal with the Renegade Chapter may actually end up, in whole or in part, becoming corrupted and joining with those they were sent to destroy, just as happened to many among the Traitor Legions so long ago.

An example of just such an outcome infamously took place in the 34th Millennium during the Obscuran Uprisings. During the curse of 400 Terran years of anarchic separatist rebellions that shook much of the Segmentum Obscurus, at least 7 Loyalist Space Marine Chapters broke their oaths to the Emperor and took part in the looting and pillaging of hundreds of these Imperial worlds. Of these Chapters, 2 of them, the Sons of Vengeance and the Silver Guards -- had at first fought on the side of the Imperium but turned Renegade after their actions against the Chaotic Free Council of Hannedra II.

The Forces of Chaos
The Forces of Chaos is an all-encompassing term that includes the Chaos Space Marines and all the other beings and entities who serve the Ruinous Powers of Chaos and make war upon the Imperium of Man and the many other intelligent races of the Milky Way Galaxy. Among their number are included the Traitor Legions and Renegade Space Marines, human, mutant and alien Chaos Cultists, Traitor Imperial Guard, Traitor Titan Legions, the Tech-Priests of the Dark Mechanicus, Chaos Spawn cannon fodder, and daemons of every shape and level of power as well as countless other foul beings too horrific to be mentioned here. All of these forces can be led into battle by the Chaos Space Marines, who are collectively the most powerful mortal servants of the Ruinous Powers who have ever lived.

The Lost and the Damned
There are also many normal humans and mutants who serve the Ruinous Powers as Chaos Cultists or belong to ancient regiments of the Imperial Army, the Traitor Titan Legions or the Dark Mechanicus. These groups joined Horus in his rebellion and then fled with the Traitor Legions into the Eye of Terror 10 millennia ago after Horus' defeat. These groups are often used by the Chaos Space Marines to bolster their ranks. These Traitors, mutants and heretics are collectively labelled the "Lost and the Damned" by the Inquisition.