Imperium of Man

"The martyr's grave is the keystone of the Imperium."

- The Liber Imperialis

The Imperium of Man is a galaxy-spanning interstellar human empire, the ultimate authority for the majority of the human race in the Milky Way Galaxy in the 41st Millennium AD. It is ruled by the living God who is known as the Emperor of Mankind. However, there are other humanoid species classified as Imperial citizens, mainly mutant offshoots of genetic base-line humans who are known as Abhumans and include such human sub-races as the Ogryns, Ratlings and Squats. The founder and ruler of the Imperium is the god-like Emperor of Mankind, the most powerful human psyker ever born. The Emperor founded the Imperium over 10,000 Terran years ago in the late 30th Millennium during the Unification Wars on Old Earth following the terrible period in human history known as the Age of Strife. The Emperor continues, at least nominally, to rule the Imperium as both its political master and its primary religious figure, though His badly damaged body is interred within the cybernetic life support mechanisms of the arcane device known as the Golden Throne following His mortal wounding during the interstellar civil war known as the Horus Heresy. Because of this terrible fate, the Emperor is incapable of interacting with others on a day-to-day basis and has left the basic governance of His Imperium to the Senatorum Imperialis, an oligarchic ruling council of the most powerful lords and Adepts in the galaxy.

The Imperium of Man is a war-torn empire, teetering on the brink of collapse. For 10,000 Terran years it has been ruled by the deathless Emperor, a being of almost limitless psychic power, to whom thousands of souls are sacrificed daily. The peoples of the Imperium live in a place where daemons are real, mutation is frequent and death is a constant companion. To be alive in the late 41st Millennium is to know that the universe is a terrifying and hostile place. It is a place where you are but one amongst billions and, no matter how heroic your death, you will not be missed. A truly vast domain, the Imperium is spread amongst the many stars of the galaxy. Its territories encompass untold millions of stars and countless more human lives. In its name, terrible wars are fought and desperate sacrifices made, yet even this river of carnage and blood is a small price to pay, for the Imperium is the guardian of Mankind. Were it to pass into nothingness, so too would the human race, destroyed by enemies uncountable, to the braying laughter of the Dark Gods.

The Imperium is the largest and currently most powerful political entity in the galaxy, consisting of at least 1,000,000 human-settled worlds dispersed across most of the Milky Way Galaxy. Consequently, an Imperial planet might be separated from its closest neighbour by hundreds or even thousands of light years. As a stellar empire, the size of the Imperium cannot be measured in terms of contiguous territory, but only in the number of planetary systems under its control. However, most humans in the galaxy have little day-to-day contact with the government of the Imperium unless they serve in one of its Adepta or run afoul of its various protectors, such as the Inquisition or the Adeptus Arbites.

The Imperium is primarily an interstellar tribute empire, allowing its member worlds to largely govern themselves as long as they recognise the authority of the Emperor and His servants and support the state religion, the Imperial Cult, which holds the Emperor to be the one, true God of Mankind. Every world of the Imperium must also pay the Imperial taxes levied on them in the form of men and materiel that is known as the Imperial tithe. These resources go to the service of the Imperial Guard and the Imperial Navy, the armed forces which keep the Imperium united and safe. The Imperial tithe supports the overall economy of the Imperium by redistributing resources where needed, usually to shore up one region of the Imperium where conflict is raging by drawing resources from more peaceful sectors. In general, the Imperium promotes the development of a neo-feudal political system, which the High Lords of Terra and the Inquisition have long believed to be the most stable form of human government. There are few human-settled worlds in the galaxy where any but the most wealthy nobles have any say in the government of their planet, and the Imperial establishment generally characterises any movements toward "democracy", self-rule or the overthrow of the neo-feudal system as outright heresy against the divine plan of the God-Emperor. This intense need for political stability and the growing military demands upon the Imperial system presented by the myriad and growing threats of the 41st Millennium have created a repressive and stagnant galactic government. In the present Imperium, science and human progress have essentially been halted in service to the need to simply maintain the crumbling status quo. It is not for nothing that many Imperial savants consider the current age the "Time of Ending" for Mankind.

Several alien species and dark forces (the Forces of Chaos, the Tyranids, the Eldar, the Dark Eldar, the Orks, the Tau, and the Necrons) increasingly challenge the supremacy of the Imperium and humanity's predominant place in the galaxy. From within its own creaking and increasingly stagnant and repressive edifice, the Imperium is threatened more insidiously by rebellion, mutation, dangerous psykers and subversive Chaos Cults. However, despite its myriad problems, without the admittedly authoritarian and often harsh protection of the Imperium, Mankind as a whole would have fallen prey to the countless perils that threaten it. Without the Imperium of Man and Mankind's faith in the Emperor who guides it, the human race would have become extinct long ago.

History
The Imperium was founded by the Emperor of Mankind, also called "The God-Emperor" and the "Master of Mankind", at the end of the Age of Strife, in the 30th Millennium AD. The Emperor, an immortal being born around the year 8,000 BC in central Anatolia on Old Earth, was the collective reincarnation of all the human shamans who possessed true psychic abilities during the Paleolithic and Neolithic Ages. Imbued with their combined psychic, physical and intellectual power, the Emperor was born an immortal being of unparalleled physical strength, psychic ability, charisma and intellect. The Emperor helped humanity as a whole survive and prosper through the long millennia. In various eras of human history He intervened through various personas, some of them well-known historical personages, to guide Mankind, though such interventions were always brief and shrouded in legend and historical mystery. At the end of the Age of Strife the man who would become the Emperor finally took a direct, public, and permanent role in shaping the future of humanity, believing that the damage done to the human race by 5,000 years of terror, isolation and violence could not be reversed unless He openly guided humanity as its leader. As such, He shed all His prior identities and simply revealed Himself in the 30th Millennium on Terra as the Emperor of Mankind, determined to unite the entire species under His stern but benevolent rule. He intended to replace superstition, fear, poverty and intolerance with reason, science, progress and hope.

Prehistory
The Age of Strife, also sometimes called Old Night, was a 5,000-year-long period of anarchy, war, and destructive technological regression from the 25th to the 30th Millenniums that brought Mankind to the brink of extinction -- and reversed the highly advanced scientific and technological discoveries made by the galaxy-spanning interstellar human civilisation of the Dark Age of Technology that had preceded it. The Age of Strife was caused by the negative psychic and physical effects of the vicious Warp Storms that ravaged large portions of the galaxy beginning in the 25th Millennium, which were the "ripples" in realspace of the psychic gestation of the new Chaos God Slaanesh in the Immaterium. Slaanesh was forming within the Warp as a result of the growing hedonism and utter excess of the ancient Eldar empire in the millennia before its Fall. One result of the Warp Storms was the impossibility of faster-than-light travel or telepathic interstellar communication through the ravaged currents of the Warp, which led to the subsequent isolation of human colony worlds and star systems separated by multi-light-year distances. Human civilisation in the colonised portions of the galaxy fragmented, and where it survived, it took on wildly different forms. On Earth, the planetary economy collapsed with the loss of interstellar trade and communication with the rest of humanity even as the social order broke down. Wars, rebellion, and disease were rampant. Vast swathes of the advanced scientific and technical knowledge accumulated in the previous millennia was lost or forgotten, and a slow descent into pre-industrial barbarism seemed inevitable. Brutal warlords emerged, who carved out new kingdoms to serve as their fiefdoms. The emergence of these often brutal neo-feudal kingdoms, the new nations of the people later termed "techno-barbarians" by Imperial historians, imposed an uneasy peace on the Earth that was frequently interrupted by feudal conflicts. The human race seemed on the brink of extinction at the start of the 30th Millennium, when the man who would become known as the Emperor of Mankind once more inserted Himself into the affairs of humanity.

The Great Crusade
The Emperor sensed that the Warp Storms that had marked the Age of Strife were starting to subside, and that this offered an opportunity for Mankind to reunite in pursuit of a new Golden Age. The Emperor first emerged from his secret fortress beneath the Himalazian (Himalayan) Mountains after ca. 800.M30 to unify all the techno-barbarian states of ancient Terra under His rule through either diplomacy or the waging of the brutal military campaigns later called the Unification Wars against the techno-barbarians tribes that ruled vast swathes of the Earth's blighted surface. These wars were waged with soldiers later known as the Thunder Warriors who had been genetically-engineered by the Emperor's genius to be faster and stronger than base-line humans. Such warriors would provide the early foundation from which He would later decide to create the Space Marines.

After conquering the last of the independent techno-barbarian states of Old Earth, the Emperor began to lay the foundations of His burgeoning Imperium. Understanding that no one man, even one such as He, could rule alone, the Emperor formed his War Council, comprised of his most able generals and a number of high-ranking administrators, the most formidable of which was known as Malcador the Sigillite. Malcador was not a warrior but a man of learning with the bearing of a priest. His origins unknown to all save perhaps the Emperor himself, whom some believed was distantly related, Malcador was appointed to run the Emperor's Palace and Court, and through this managed the administration of newly conquered Terra as his master's left hand. Where Terra had been a place of unending war it now became a place of unceasing activity, production and planning.

Just as the conquest of Old Earth was complete a mighty and unforeseen cosmic event occurred. A massive shock wave blasted across the Immaterium, clearing the warp storms that had plunged the galaxy into tumult and raged for more than five thousand years. It seemed to some divine providence, fuelling the beliefs of those that considered the Emperor to be himself divine (no matter how much he decried this claim). The way to the galaxy was now open and the Emperor's armies would now be able to take to the stars, with the other planets of Terra's solar system the first step upon the road. The Great Crusade had truly begun.

After conquering the last of the independent techno-barbarian states of Terra, the Emperor secured the allegiance of the Cult Mechanicus of Mars who controlled the most advanced remaining industrial fabrication and scientific research facilities in the human-settled galaxy. The Emperor promised to protect the Tech-priests and respect the sovereignty of the Mechanicum and their Forge Worlds across the galaxy, affording them a level of independence unequalled within the Imperium. Furthermore the Emperor gave to the service of the Mechanicum six of the Houses of Navigators, so that their ships might once again travel safely through the Warp. The powerful Fabricator-General of Mars was given a seat on the War Council of the Great Crusade. With access to the giant factories of Mars, this enabled the Emperor to vastly increase the power of his Legions with improved wargear and supply, and in addition the Tech-priests of Mars lent their arts to construction of the massive warp-capable battleships that could transport the Emperor's Legions across the galaxy, and provided the mighty city-crushing war machines known as the Titans to the ever-expanding Imperial military.

With Mars now part of the Imperium, the Great Crusade began in earnest and the rest of the solar system was the first region of space to be conquered by the Emperor and his newly rearmed and re-equipped Space Marine Legions. The Legiones Astartes secured the scientific research installations and spacedocks of Luna which had once been controlled by the Selenar gene-wrights. 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. Alien invaders were flushed from the moons of Saturn and Jupiter and their wretched enslaved human inhabitants repatriated to Earth, the once-human creatures of the Neptunian Deeps were exterminated without mercy, and the baleful false-world of Sedna at Sol's edge-light was boiled away to vapour under the guns of the new-forged war fleet. The next step was beyond.

The Great Crusade marked the beginning of the period that would later be known as the Age of the Imperium. This campaign was a mammoth operation on an unconceivable scale and complexity involving billions of troops and tens of thousands of ships, and it is perhaps true that only a mind such as the Emperor's could have had a hope of successfully comprehending and executing it. In order to manifest this conquest the Imperium's forces were divided up into an expanding and frequently reconfigured series of Imperial Expeditionary fleets -- semi-autonomous battle groups assigned to voyage the stars and make war in the Emperor's name. they were composed in chief of a bewildering array of void ships great and small. The paths of these fleets were dictated both in general by the Emperor and his War Council, but also as the will of their commanders who were entrusted to seek out the enslaved and destroy the alien under their own sway.

But even before He had begun His campaign to reunite the Earth, the Emperor had used His highly advanced knowledge of genetic engineering and the psychic arts to create the Primarchs, 20 superhuman military commanders possessed of preternatural physical, mental and social attributes who had been created through the fusion of variations of His own genetic material with the power of the Warp. The Emperor had known that the greatest foe of His plans to reunite the human race and bring Order to the galaxy would be the Ruinous Powers of Chaos and their daemonic servants. He had sought to protect his gestating Primarchs from the Dark Gods while they grew in their gestation capsules in the Emperor's secret laboratories deep beneath the Himalazian (Himalayas) Mountains, but the Chaos Gods saw through all his wards and protections. They opened a Warp portal in the Emperor's own laboratory and stole the infant Primarchs away from Terra, scattering them across the galaxy and tainting many of them with the power of Chaos.

Undeterred by this tragedy, the Emperor utilised what remained of the Primarchs' genetic material. He had first crafted the Thunder Warriors to unite Old Earth. He then proceeded in the last days of the Unification Wars to transform ordinary Terran men into a new corps of transhuman warriors who would lead Mankind back out into the stellar void. These men were the Emperor's Astartes, theLegiones Astartes, superhuman warriors who knew no fear. The Imperial military comprised the entire force of the Space Marine Legions, who thanks to influxes of technology and resources from around the solar system were growing in numbers and capability at an exponential rate. The Space Marine Legions were the spearhead -- the Great Crusade's killing edge against which the strength of a foe was broken and which toppled empires, human or alien, by ripping out their hearts.

During the 200 standard years that the Great Crusade spread the Imperium across the galaxy, the Emperor slowly made contact once more with all of His scattered gene-sons, the Primarchs, and to each He gave command of the Space Marine Legion that had been created from that Primarch's specific genome. Horus was the first of the Primarchs to be rediscovered, on the barren Mining World of Cthonia only a few light years from Terra itself. Horus campaigned with the Emperor for 30 Terran years before the next of the Primarchs was recovered, and during that time the two developed a special bond, the deep affection between a father and His favoured son. The Astartes Legions, combined with the might of the Imperial Army (which was later separated into the Imperial Guard and the Imperial Navy after the Horus Heresy), reunited thousands upon thousands of human-settled worlds into one interstellar civilisation, in the name, and under the rule of, the Emperor and the Imperium of Man. But the Great Crusade was ended abruptly by the corruption and treachery of the Imperial Warmaster Horus, who was both the Primarch of the Sons of Horus Legion and the overall military commander of the Great Crusade in its last days. This was an honour that had been granted to him by the Emperor, who had sought to leave the campaign so that He might return to Terra and oversee a highly-secret project intended to open up the Eldar Webway to human use.

But Horus and many of the other Primarchs deeply resented the Emperor's absence from the Great Crusade and were even more disturbed by His attempts to replace the direct rule of the Imperium by the Emperor and His Primarchs with a bureaucracy of normal humans. Having established the Council of Terra, the new governing body of the Imperium to carry out the day-to-day work of ruling tens of thousands of worlds and trillions of human beings, the Emperor took refuge in his vast laboratories and workshops beneath the Imperial Palace. He began work in earnest on his new project. While the Emperor was locked away in his subterranean factories, trouble was brewing. The formation of the Council proved to be a contentious decision with the distant Primarchs, who were appalled when news of the formation of the Council of Terra finally reached them on the frontiers of the Great Crusade. Some of the Primarchs took great exception to being ruled by those they deemed less worthy of such an honour than themselves. The less stable Primarchs felt that this was a betrayal of all they had fought and won in the Emperor's name and that their victories now counted for nothing. Some of the Primarchs took great exception to being ruled by those deemed less worthy of such honours than themselves. They, and many of their Astartes, felt that it was they who had suffered and sacrificed the most to build the Imperium and thus it was they who should have the greatest say in how it was ruled, not a council composed of effete Terran nobles and faceless bureaucrats. This was one of many growing resentments that allowed the Ruinous Powers to infect and corrupt several of the Primarchs.

Riven by jealousy and ambition, Horus proved to be easy prey for the temptations of the Chaos Gods and the machinations of his own brother Lorgar, the Primarch of the Word Bearers Legion, who had come to secret service of Chaos during the course of the Great Crusade. Given the opportunity, the Dark Gods falsely convinced the arrogant Warmaster that the Emperor had intended all along to simply use the Primarchs and the rest of humanity to transform Himself into a God. Enraged at this notion, the Ruinous Powers then promised Horus their support in his bid to seize the Imperium for himself. Horus ultimately convinced 9 other Primarchs and their Space Marine Legions to join his cause and serve the designs of Chaos. He instigated the terrible Horus Heresy -- a galaxy-wide rebellion against the Emperor -- and eventually one-half of the Imperium's vast military forces, as well as elements of the Mechanicum, rallied to the Traitors' cause, unleashing the greatest conflict Mankind had ever known upon an unsuspecting galaxy.

The Horus Heresy
The Horus Heresy was fought across the galaxy for more than seven years, beginning with the terrible Istvaan III Atrocity where Horus cleansed four of the Traitor Legions under his command of their remaining Loyalist elements and the Drop Site Massacre of Istvaan V, where Horus and his Traitor Legions nearly decimated three entire Loyalist Space Marine Legions through the most basest of treacheries. Horus, sought to achieve a swift and decisive victory over the Emperor after pledging his soul to the service of the Ruinous Powers of the Warp, leading his Traitor forces directly to Terra over the next seven standard years, slaughtering tens of billions of people and destroying much of what the Emperor had built over the last two centuries. In a final decisive battle between the Emperor and Horus at the end of the great Battle of Terra, the Warmaster was slain, leading to the end of the rebellion when the Forces of Chaos naturally began to turn on one another without Horus' ambition, titanic charisma and influence to keep them united in pursuit of a single goal. Over the next several years, the Traitor Legions and their Chaotic allies slowly withdrew from Imoperial space, eventually fleeing Imperial pursuit into the great Warp rift in the Segmentum Obscurus known as the Eye of Terror.

However, the Master of Mankind was Himself mortally wounded during the battle, which took place on Horus' Chaos-twisted Battle Barge, the Vengeful Spirit, in orbit above Terra. The Emperor's body was recovered by the Primarch Rogal Dorn of the Imperial Fists Legion and according to His last instructions, the Emperor was placed on the life-preserving Golden Throne, an arcane artefact from the Dark Age of Technology that served as both a psychic amplifier and a potent cybernetic life-support system that the Emperor had originally intended to use to create a portal into the Webway. For over 10,000 years now, the Emperor has remained immobile on the Golden Throne. Though physically a broken, dying carcass incapable of movement and unable to communicate normally with the outside world save through the rare telepathic contact and the Emperor's Tarot, the Emperor's psychic will, almost omnipotent, extends through the Immaterium across the million worlds of the Imperium. It produces the psychic beacon of the Astronomican that is used by all Imperial starships to travel through the Warp, soul-binds weaker psychic humans to make them useful Sanctioned Psykers of the Imperium while leeching the lives from other psykers to sustain His psychic presence, and struggles against the encroaching daemons of the Warp, protecting Mankind from their realspace predations. In all this, the Emperor endures the constant agony of His dying body only through a sheer exercise of will, and the sustenance that the life forces of the sacrificed psykers provide. Yet the masses of humanity worship the Emperor as both a God and their only saviour. It is an article of faith in the Imperial Cult that against all the threats faced by the human race, only the Emperor protects...

The Scouring
In the wake of the Horus Heresy, the Imperium was a dismal, shattered thing. As the beauty and grandeur of the Imperial Palace had been burned black in the flames of betrayal, so great swathes of the Emperor's star-spanning realm had suffered a similar fate. The Master of Mankind was a broken husk, and his dream of unity erased forever. Yet for all this, the Imperium retained might enough to exact a bloody revenge upon its foes. There could be no forgiveness for the crimes of the Traitor Legions -- those who now ruled in the Emperor's name had neither the ability nor the desire to prevent a war of reciprocity. So began the time known in the histories of the Imperium as the Scouring. Before actually being confined for all time within the life support mechanisms of the Golden Throne, the Emperor had pronounced judgment on the Traitors: he declared them Excommunicate Traitoris, and determined that they were to be driven into the hellish region of the Warp rift called the Eye of Terror, which would hold them for all eternity. All records and memory of the Traitor Legions were to be expunged from the Imperial archives. Worlds such as Istvaan V and Davin would be scoured clean of all life because of their corruption by Chaos. The Traitor Legions' associated troops from the Dark Mechanicus, the Titan Legions or the regiments and starships of the Imperial Army that had turned to Chaos were to be destroyed or driven into the great Warp rift known as the Eye of Terror. It would be as if the Traitor Legions had never existed to sully the Imperium with their betrayal.

This was a period of monumental violence, of confusion and darkness. Though the newly founded Imperium fought to root out corruption and expose wrong-doers to the cold light of Imperial justice, the galaxy's scope and dark, shadowed reaches worked against them. With new betrayals and cries for vengeance emerging daily, a great many bloody-handed deeds went unseen. The ravaged Space Marine Legions were no exception to this, with many striving to cover up their own misdemeanours or exact their pound of flesh from those who wronged them. The Dark Angels, the Space Wolves, Iron Hands and even the Ultramarines, all followed their own agendas as the wars of the Great Scouring gathered pace. Fighting continued for another seven standard years after the Heresy had ended with Horus' death on the bridge of his great flagship, the Vengeful Spirit, before the Traitor forces were wholly destroyed or exiled into the Eye of Terror. Many Chaos-corrupted star systems were cleansed and placed under the watch of the newborn Inquisition. Horus' death had not ended the fighting, but it had renewed the resolve of the Loyalists to destroy the Traitors. Many Imperial worlds during the Heresy had refused to commit their forces to either side, or seceded entirely from the Imperium to regain their independence. Such indecision was punished by Loyalist and Traitor forces alike. These forces were often bled white attacking the rebel strongholds of worlds that only wanted to be free of the Imperium entirely, whether it swore allegiance to the Emperor or to the Dark Gods.

Changes swept both the military and the offices of government. The Space Marine Legions, the vast fighting formations so instrumental in Mankind's victories during the Great Crusade, were broken down into many smaller Chapters comprised of 1,000 Astartes. Overseen by Roboute Guilliman, the Primarch of the Ultramarines Legion, he penned his magnum opus, the Codex Astartes -- a great and sacred tome which covered every conceivable topic of military organisation, strategy and tactics. This transition allowed for greater tactical flexibility without placing the command of an entire Space Marine legion into the hands of one individual -- never again would the awesome power of one hundred thousand Space Marines be misused. The Loyalist Space Marine Legions that had been decimated during the Drop Site Massacre on Istvaan V -- the Raven Guard, Iron Hands and Salamanders -- were slowly reestablished using what little gene-seed the survivors had managed to escape with. The original First Founding Space Marine Legions were divided into smaller Successor Chapters - one Chapter maintained their parent Legion's original name, badge and colours, while the remaining Chapters took new names and heraldry. These original Chapters are known as the Second Founding Chapters, which occurred in the early 31st Millennium, which coincided with the beginning of what was known as the Reformation of the Imperium.

Another vast change wrought upon the Imperium's mighty military redefined the nature of the Imperial Army. Once including both the great battleships that plied the stars and the countless soldiers that landed to fight planetside, now the two were divided into the Imperial Navy and Imperial Guard. Across all the agencies of the Imperium, offices and institutions were split, their previous responsibilities fractionalised into separate functions and departments. Many of the countless branches within the sprawling Adeptus Administratum were spawned at this time. With the instigation of these changes, it was not unusual for two separate organisations, each unaware of the other, to be tasked with the same jobs, such as verificator scribes and tithe enumerators poring over the same data, each producing the same reports. These byzantine systems were put in place as fail-safe measures, which have since spiralled out of control into administtative excess. Beyond any such bureaucracies, and standing watch over all, was the newly formed Inquisition, a secretive organisation outside the established hierarchies. Ever vigilant, their role was to question everything in their constant search for threats to humanity. None save the Emperor himself escape their uncompromising and watchful gaze.

Imperial Stagnation
"Mankind stands upon the bring; on the one hand lies a realm of unimaginable power, on the other awaits darkness, death and utter damnation. Only those that follow the guiding light of the Emperor may save their souls."

- Inquisitor Damarn, Ordo Malleus

The Imperium of Man at the end of the 41st Millennium is a dystopic society by the standards of the men and women of the 21st Century. The unexpected horrors of the Horus Heresy fatally weakened the nascent Imperium, but more importantly, starting with the Emperor himself, claimed some of its best warriors, technocrats, administrators and diplomats - who fell either in battle with the Traitor Legions or were corrupted by Chaos themselves. But perhaps the most significant consequence seems to have been that like the Emperor, the Imperium itself entered a slowly decaying stasis, while Chaos and the Imperium's myriad xenos enemies are ascendant.

It is known that the period immediately following the Heresy was one of near-anarchy, and that the continuity of the Imperium was not assured. Roboute Guilliman, the Primarch of the Ultramarines, was one of those credited with taking decisive action that kept the Imperium together, possibly with the help of other Loyalist forces and of newly-created Imperial organisations such as the Inquisition and the Officio Assassinorum (it is known that at least one Assassin Temple, the Callidus, was already operating with Imperial sanction, and had successfully assassinated Konrad Curze, the Primarch of the Night Lords Traitor Legion). Ironically, while the Imperium survived, it also seems to be fulfilling predictions or prophesies made about its future by a variety of Chaotic enemies, Traitors, and more neutral or potentially sympathetic observers like the Eldar. Supreme among such ironic twists is the deification of the Emperor and the attendant creation of the Ecclesiarchy, the galaxy-wide church dedicated to the Imperial Creed that teaches that the Emperor is the God of Mankind. The Emperor's express purpose and one of the pillars of the pre-Heresy Imperial doctrine known as the Imperial Truth that was spread by the Imperial forces during the Great Crusade was the elimination of superstition and of belief in supernatural powers, gods, and religion and the promotion of reason and science. It is worth noting that among the ploys used by the Ruinous Powers to turn Horus to their service were uncannily accurate visions of the post-Heresy Imperium in which the Emperor and his Loyalist Primarchs were worshiped by the Imperial masses as a God and his saints, respectively. Of course, unknown to Horus, this was a future caused by his actions, not prevented by them.

Another measure of the Imperium's stagnation has been the lack of real technological progress over the last 10,000 Terran years and a fear of unknown or ancient technology that sometimes borders on irrational superstition. It seems that the last major era of human technological advancement was the era of discoveries and technological applications made during the planning and execution of the Great Crusade.

In short, the Imperium has become a repressive regime marked by extreme levels of superstition, political repression, religious intolerance, bureaucratisation, economic stagnation, technological regression and inequality. Corruption and injustice are rampant and human life is increasingly worth very little in a galaxy teeming with literally trillions of people. But though the Imperium is repressive and stagnant, it is also the only thing holding the enemies of Mankind at bay. Many in the highest levels of the Imperium know that it must reform if it is to survive, but they fear that the cure might very well kill the patient. And in small pockets of the Imperium there are men and women willing to shoulder the burden of making their small corner of the universe a better place for all by shouldering the responsibilities and the burdens of heroes.

But recently, in 999.M41, the Adeptus Mechanicus has secretly reported to the High Lords of Terra that in addition to all the other problems besetting the Imperium, the mechanisms of the Golden Throne are malfunctioning and they no longer possess the necessary knowledge to repair them. Whether the nobles of the Imperium like it or not, a terrible change is coming...

The Adeptus Terra
The Imperium covers a wide area of galactic space, sprawling over countless worlds. There are few universal constants amongst these wildly varying planets. Culture, language and even the human form appear in seemingly infinite variation across the galaxy. One of the few constants (at least amongst those worlds of the Imperium that are aware of its existence) is the network of Imperial feudal obligation and responsibility. Each Imperial planet owes fealty to a Planetary Governor. This individual in turn renders to the Imperium’s priesthood a tithe of men, materials and loyalty. The governor is also expected to reject enemies of the Imperium, and to ensure that the psykers upon his planet do not fall into witchery or daemonic possession. In return, the governor can call upon the Priesthood of Earth (or Adeptus Terra as they are properly known) in times of dire threat and request aid. The Adeptus Terra comprises a bewildering variety of departments, bureaus, sub-divisions and offices, each of which deal with a particular aspect of maintaining the continuity of the Imperium. Each order has an obligation to care for its given area of control.

This weight of responsibility grows as feudal obligation passes up through a mind-numbing array of ranks within each Adepta. From lowly scribes computing a hive world’s annual nutra-slurry yield to mighty Sector Commanders overseeing the assemblage of a Crusading fleet, vassalage and power passes ever upwards to the titular heads of the Imperium, the High Lords of Terra. These powerful individuals rule from ancient Terra in the Emperor’s name. Based on Terra itself, the Emperor of Mankind is a silent being of awesome power. His withered carcass is cradled within an arcane artefact of incredibly advanced design from the Dark Age of Technology. This Golden Throne, as it is known, sustains the Emperor’s life force whilst He guards humanity from the Daemonic beings that would destroy Mankind utterly. For hundreds of centuries He has fought this psychic battle and for hundreds of centuries mankind has offered Him their fealty, worship and devotion.

The Imperium is still nominally ruled by the Emperor of Mankind as an absolute monarch. However, since his ascension to the Golden Throne, the duty of actual high-level governing of the Imperium falls to the Senatorum Imperialis - the Imperial Senate, formed by the 12 High Lords of Terra. The identities and responsibilities of these High Lords may vary, as individuals inevitably die and their influence grows and wanes, but its members are always the leaders and representatives of the most powerful Imperial organisations.

Ultimately, the High Lords are in control of the Imperium as a whole, and are responsible for maintaining the functioning of the Imperium through the Adeptus Terra and the Imperial Commanders who govern each Imperial world, sub-sector, sector and Segmentum. However it is not feasible to maintain a completely centralised government over such vast interstellar distances, even with faster-than-light travel and telepathic communication. This means that the Imperium is structured like a neo-feudal confederacy, with the planetary rulers acting as feudal lords subject to the higher authority of the Adeptus Terra and responsible for providing men to the Imperial Guard, but largely free to run their worlds day-to-day as they see fit. Therefore, many Imperial worlds are left to fend for themselves without any direct involvement of the central government save in a time of crisis.

The flow of information in the Imperium is tightly controlled, with several Imperial bodies withholding information (chief among these is the Inquisition, an ever-present Censor) or engaging in misinformation and propaganda (such as the Ecclesiarchy among others). Other organisations zealously protect information that could be used for the benefit of the Imperium as a whole, such as the widespread hoarding of technological and scientific information that is the common practice of the Adeptus Mechanicus. The censorship has been justified by the terrible and dangerous nature of some of this information, and by the sheer immensity of the task of governing the Imperium.

The stellar empire that is the realm of the Emperor is so massive and sprawling that it includes a wide variety of diverse worlds, ranging from pastoral Agri-worlds to jungle planets inhabited by Neolithic savages to polluted ecumenopoleis, great hive cities that are home to billions of people that in some cases cover entire planets. For example, the world of Gudrun is similar to an idyllic 18th Century Georgian-era Great Britain, with stately manors controlling vast estates of rolling green hills studded with small agricultural villages, while Catachan is a hellish Death World covered in a deadly jungle that is populated by giant carnivorous plants and animals (see Planets of Warhammer 40,000).

Most of the organisations or organs comprising the Imperium's government are divisions of the vast Adeptus Terra (also referred to as the Priesthood of Earth), the great bureaucracy of the Imperial government. The priesthood which serves the Lord of humanity is often referred to as “the right hand of the Emperor”. It falls to the Adeptus Terra to interpret His will and minister to the Imperium. Many hundreds of thousands of souls labour across the galaxy to serve this vast organisation. There are numerous ancient institutions that make up the priesthood, each with various names on various planets. These varying Adepta, as they are traditionally known, each have a specific function to carry out in the Emperor’s name.

There are countless divisions within the Adeptus Terra, and some are so secretive that their existence is known only to a few officials at the very top of the massive Imperial hierarchy. Perhaps the most well-known of the "secret" organisations is the Inquisition, the Imperium's secret police, which was created at the start of the Horus Heresy by the Emperor's regent, Malcador the Sigillite, to seek out any hidden threat to the Imperium from without or within. The existence of the other secret Imperial organisations is known only to the higher Imperial echelons. For example, one of the most secretive of Imperial organs is the Officio Assassinorum, the arm of the Imperium tasked with carrying out assassinations deemed necessary to the Imperium's security and survival. Other organisations are secret enough that nothing other than the fact that they exist is known, such as the saboteurs of the Officio Sabatorum and the Templars Psykologis, who carry out psychological warfare operations.

The most important and well-known Imperial Adepta include:


 * The Adeptus Administratum, which is responsible for the day-to-day administrative and bureaucratic functions of the entire Imperium. The Administratum is the largest division of the Adeptus Terra, and contains among its teeming numbers of Adepts countless scribes and petty officials. It administrates the Imperium at every level, assessing tithes and taxes, conducting population censuses, recording and planning and even delineating which threats to the Imperium must be dealt with and by which of the Imperium's myriad military forces. The Administratum consists of innumerable subdivisions, offices and departments. Needless to say, its servants are legion. At the will of the Adeptus Terra, the Administratum collects the Imperial tithe, sends out colonists, mobilises the military, catalogues planets and much, much more. Truly stultifying levels of bureaucracy exist within the Administratum and some wayward souls believe that the Imperium survives despite, rather than because of, its efforts. The Administratum has become synonymous with the Adeptus Terra in many places and, incorrectly, the terms are often used interchangeably. The faceless servants of the Administratum can be found all over the Imperium, ensuring that all things are accomplished in the correct manner, even if that may take a thousand years.
 * The Departmento Munitorum, itself officially a department of the Adeptus Administratum, which is responsible for supplying the armaments, materiel and basic logistics for the Imperial Guard across the galaxy.
 * Adeptus Astra Telepathica is the Imperium's network of Astropaths, the Sanctioned Psykers who are responsible for telepathically transmitting faster-than-light messages through the Immaterium and maintaining Mankind's fragile network of interstellar communications across the galaxy. Blessed are the blind, for they have looked upon the glorious light of the Emperor directly and no true servant of the Golden Throne could ask for more. Through the agonising ritual of soul-binding, these psykers have been gifted with a small portion of the Emperor’s own incredible will. Thus protected from the worst evils of predation by Warp entities, these unseeing servants of Terra can fulfil their primary function, preserving communication between the far-flung worlds of the Imperium.
 * The Adeptus Astronomica is the Adepta responsible for maintaining the Astronomican which is used by the mutant psykers known as Navigators to navigate all Imperial starships, military or civilian, through the Warp. The Black Ships of the Adeptus Astra Telepathica bring thousands of psykers to the birthplace of Mankind every day and many of those so tithed find themselves contributing to the vast psychic choir of the Astronomican. This steady beacon burns bright in the Warp; it is the Emperor’s will manifest, shining from Terra, and guides Navigators across the Imperium. The process of lending their psychic power to focus the beam quickly leaves the choristers as lifeless husks, but they give themselves willingly, for without the Astronomican the Imperium would cease to exist.
 * The Navis Nobilite is the Imperial aristocracy that is comprised of noble familes of mutant Navigators who pilot all Imperial vessels, military or commercial, through the constantly shifting dangers of the Warp and were the first known humans to display psychic abilities during the Dark Age of Technology.
 * The Adeptus Mechanicus is the priesthood of technicians and scientists dedicated to the religion of the Cult Mechanicus who build and maintain all advanced Imperial technology, vehicles, starships, and weapons of war and whose headquarters is located on Mars. The Adeptus Mechanicus believes that all knowledge in the universe is a sacred emanation of the Machine God and that the Emperor of Mankind is His Omnissiah. Needless to say, the Tech-priests and Adepts of the Mechanicus are viewed as only slightly better than the average heretic to the Priests of the Ecclesiarchy. Outside of Mars, the Mechanicus controls all of the Imperium's Forge Worlds, the planets where the production of most of its advanced technological items is done. The domains of the Adepts of Mars exist semi-autonomously within the Imperium, an empire within an empire, a right given to them by the Emperor Himself when he signed the Treaty of Mars that created the modern Imperium in the late 30th Millennium. They are the guardians of technology, the magi of machinery. It is theirs alone to know how to coax forth the life of a sun in a plasma containment field, how best to apply the blessings of activation and maintenance to the massive Titan war machines, how to ensure that the engines of the Emperor’s starships run smooth and true. The Adepts of Mars worship the Emperor in the guise of the Machine God. To them, Mankind is in a fallen state from the height of its powers during the Dark Age of Technology, when the secrets of the universe were known to all. Knowledge then, lies in the past and the Adeptus Mechanicus will go to any lengths to uncover the great secrets of antiquity, scouring the universe for any scrap of information from their holy book—the Standard Template Construct system. They hold that, were the knowledge contained within the ancient STC database to be restored in full, it would reveal all of the powers of the hallowed past. The Tech-Priests venerate machines and regard them as superior to flesh. Many of them believe that the Machine God desires them to shed this weakness and so they often sport numerous bionic modifications. These mechanical enhancements add to their air of otherness and further help to set them apart from the rest of humanity. Through rune and hammer, the Tech-Adepts are the wards of the arcane and they guard their knowledge jealously. But for all their might, they are not beyond the watchful gaze of the Inquisition.
 * The Adeptus Custodes are the genetically-emgineered superhumans who serve as the guardians of the Emperor's physical form. They are essentially the Emperor's bodyguards and royal guardsmen within the Imperial Palace on Terra and they are considered the greatest warriors of the Imperium, more powerful than even the Astartes of the Space Marines. However, despite their skill in battle they very rarely ever venture beyond the confines of Terra. These are among the mightiest warriors in all the Imperium, the praetorians of the Emperor. They stand ever-vigilant outside the brazen doors which seal His holy chamber. They are entirely beyond reproach and they are among the few in the Imperium over whom the Inquisition has no power. They never leave the inner sanctums of the Imperial Palace and serve from birth to death within its hallowed halls. Yet they are among the few servants of Mankind who will ever look upon the Emperor directly, and for that they receive blessings beyond all measure.
 * Adeptus Arbites - The Adeptus Arbites are the guardians of the Lex Imperia -- Imperial Law. It is given to them to maintain order amongst the higher echelons of Imperial governance -- wherever a Planetary Governor seeks to abuse his rule, wherever populist unrest seeks to unseat the rightful dominion of the Imperium, wherever thoughts of personal gain at the Emperor’s expense cross the minds of the ruling classes, there you will find the dogged agents of the Lawgivers. The Arbites enforces Imperial Law across the galaxy and its Arbitrators possess the right to serve as judge, jury and executioners on every Imperial world.
 * Officio Assassinorum - The Officio Assassinorum is the most covert of all the known Imperial agencies, whose assassins are responsible for removing the key leaders of any enemy of the Imperium as determined by the High Lords of Terra - whether that enemy is a threat from without or within.
 * The Imperial Inquisition - The Imperium is assailed by countless enemies both from within and without. The attentions of unclean xenos, the invidious influences of the misguided followers of the Ruinous Powers, planetary unrest, mutation, rogue psykers, rebellious Imperial lords and more all work constantly to bring the Imperium down, which will lead to the ultimate extinction of Mankind. Yet somehow it survives and humanity endures. The Inquisition is one of the many reasons for the persistence of Man in an extremely hostile universe. Known as the “left hand of the Emperor”, the Inquisition operates across the Imperium and beyond to suppress and eliminate those forces that would destroy the holy dominion of Mankind over the galaxy. Inquisitors are empowered to go anywhere and do anything —- whatever they must to ensure the survival of the Imperium. Their Inquisitorial Rosetta opens all doors, and even the vaunted Planetary Governors must acquiesce to their demands without complaint or delay, lest they be themselves regarded as suspect. They will commit acts, no matter how vile, to maintain the unchanging integrity of the Imperium, and they will put whole planets to death in order to see that this is so. The members of the Inquisition vary enormously in physical appearance, methodology and mentality. Some operate alone and in secret, hidden from the eyes of the common man, while others operate openly and carry dozens of acolytes and agents in their cadre. What they do have in common is that they answer only to their Order, and each Order answers only to the Emperor. Their efforts can be checked by no Adepta and they are utterly, fanatically devoted to the defence of the Imperium. Even the most loyal and honest Imperial citizen is likely to break into a cold sweat on learning that the Inquisition is nearby -- and that suits its members perfectly. The Inquisition is itself divided into three major Orders: the Ordo Malleus, which hunts daemons and those corrupted by the Ruinous Powers of Chaos; the Ordo Xenos which eliminates the threat that other intelligent alien civilisations present to humanity's rule of the galaxy; and the Ordo Hereticus which hunts down mutants, heretics of the Imperial Cult, and all those who would threaten the Imperium from within--including within the Ecclesiarchy itself. The Inquisition's agents necessarily exist and operate beyond the control of the Adeptus Terra, since part of the Inquisition's role involves rooting out corruption and gross incompetence from within the highest levels of the Imperium itself. Inquisitors ultimately answer only to the Emperor and to themselves and they are perhaps the most powerful organisation within the Imperium after the Chapters of the Adeptus Astartes.
 * The Adeptus Ministorum is the ecclesiastical hierarchy of the Imperial Cult that promulgates and maintains control of the Imperial Creed and the galaxy-spanning faith of the God-Emperor of Mankind. The Adeptus Ministorum is not formally part of the Adeptus Terra. Rather it is a sister organisation which works hand-in-glove with the Priesthood of Earth. The Adeptus Ministorum derives its power and authority from the common Imperial belief in the Emperor’s divinity. Also known as the Ecclesiarchy, after its high priest, the Ecclesiarch, the Adeptus Ministorum is vast and powerful. Its duty is to guide and interpret the innumerable ways that humanity has found to worship the Emperor, shepherding the myriad worlds of man along the unsteady path that lies between heresy and true devotion. Whole worlds lie within its administration and on many others it represents the most powerful Imperial institution. Like the Administratum, the Ecclesiarchy is a complex and byzantine organisation. A bewildering hierarchy of priests, confessors, cardinals, novices, clerics, bishops and missionaries all owe fealty to the Ecclesiarch in the Ecclesiarchical Palace on Terra. Just as varied are the various roles within the Ministorum, from wandering missionaries, to charismatic preachers and theosophical scholars. Two of the most famous institutions within the Adeptus Ministorum are the training orphanages of the Schola Progenium and the Battle-Sisters of the Orders Militant of the Adepta Sororitas.

Imperial Military Forces
Mankind has always excelled at the art of war, and the Emperor’s armies are spread across the galaxy. The threat or effects of war are never far away, no matter where you go in the Imperium. Mankind seeks to purge the stars of its enemies, and the bloody carnage it wreaks in doing so shows no sign of abating. The Imperium’s military is at once mighty, glorious and terrible.The military forces of the Imperium include:
 * Imperial Guard - The Imperial Guard is the backbone of the Imperium’s military might. Millions upon millions of well-trained men and women, organised into thousands of regiments, make up the Guard. With Lasgun and bayonet they march upon alien battlefields and garrison vital worlds. They form the Imperium’s first line of defence and they strike the first blow in many Crusades. Its Regiments are drawn in great tithes of manpower from the Imperium’s worlds and each Regiment has a unique character and fighting tradition, from the rigid discipline of the Armageddon Steel Legion to the stealthy brutality of the pale-skinned Stygians and the unflinching bravery of the Vostroyans. Vast conscript armies, elite special forces, massive tank columns and glorious sabre-wielding cavalry can all be found in the Imperial Guard, often fighting alongside one another on Emperor-forsaken worlds they have never heard of. Regiments do not remain on their homeworlds but are raised explicitly to be sent to fight and die light years away from home. And they do die, for the Imperial Guard bear the weight of the Imperium’s wars. It is said that the Emperor knows the name of every soldier that has fallen fighting in His wars—but if that is true, He is the only one who can comprehend just how many Imperial Guardsmen have died in the ten thousand years since the Emperor "ascended" to the Golden Throne. Those who survive the grinding horrors of a lifetime of war are frequently gifted a portion of the very land they fought to conquer as a reward. As with many things in the Imperium, this is a mixed blessing indeed. The Imperial Guard Regiments are raised from the local armies of the Imperium’s worlds as part of a planet’s tithe to the Imperium. These regiments are normally deployed according to the orders of the Adeptus Terra. However, when the High Lords of Terra declare a major military campaign (often referred to as a “Crusade”) they appoint a Warmaster chosen from among high-ranking Imperial Guard officers to command the campaign's regiments. One of the most famous Warmasters, Macharius, was given the title Lord Solar when he became the Imperial Commander of the entire Segmentum Solar. Macharius proved to be the greatest Imperial general since the Horus Heresy when conquered a thousand worlds on the Imperium’s Eastern Fringe and expanded the Imperium to the very edge of the Astronomican’s reach.
 * Adeptus Astartes - The Adeptus Astartes, better known as the Space Marines, are the elite warriors of the Imperium. They are few in number and regarded with almost mythical awe by most folk, for they are inheritors of traditions founded by the Emperor Himself. The Space Marines are divided into Chapters, each possessing 1,000 Space Marines along with its own support staff and spacefleet. It is said that there are around a thousand such Chapters in the Imperium. A Space Marine is recruited in adolescence from among the most violent cultures of the Imperium. His body is hugely enhanced with new genetically-engineered organs promoting muscle and bone growth to give him immense strength, size and resilience. His mind is similarly enhanced; hypno-doctrination and sleep-learning give him both a fervent belief in the Imperium and the knowledge of weapons and tactics to bring the Emperor’s wrath to the battlefield. Upon completing his augmentation and training (which not all novices survive), he is issued with his wargear, including a suit of Power Armour. This armour is one of the most powerful symbols of Imperial might, depicted in statuary and stained-glass windows in cathedrals all across the Imperium. Equipped with nerve-fibre bundles so it moves in sync with his body, a Space Marine’s armour not only grants him great strength and protection but is a work of art, resplendent in the heraldry of his Chapter. Each Chapter is independent from the Adeptus Terra. While most will eagerly answer the summons of an Imperial Warmaster or a plea for help from somewhere in the Imperium, some Chapters have their own agendas and cannot be relied upon entirely. All, however, serve the Emperor loyally with complete devotion. All Chapters have proud traditions and distinct characteristics that translate into the way they fight. The ferocious Space Wolves, for instance, are more fiercely independent from the Adeptus Terra than most other Chapters and fight on their own terms up close with Chainswords and Bolt Pistols. The Iron Hands, on the other hand, have close ties to the Adeptus Mechanicus and are the masters of siege warfare, arming their warriors with an array of devastating heavy weapons and tanks. Many Chapters are legends, and names such as the Blood Angels, Ultramarines, Dark Angels and Imperial Fists are spoken of with reverent awe among Imperial citizens. A Space Marine Chapter has its own fleet of fast spacecraft and can react far more quickly to a threat than the Imperial Guard or Imperial Navy, making the Adeptus Astartes one of the only forces in the Imperium that can mount a rapid response to a crisis. The Space Marines are extremely few in number compared to the size of the Imperium and few citizens will ever see one in the flesh, but without them the Imperial military and the human race would slide ever faster towards destruction.
 * Grey Knights - The Space Marines of the Grey Knights Chapter are amongst the most highly specialised of the Adeptus Astartes, designed to specifically defend the Imperium against the threat of Chaos. The Grey Knights are permanently attached to the Ordo Malleus as its Chamber Militant and their leaders are rumoured to serve terms as members of the Inner Conclave of the Inquisition. No ordinary warriors, Grey Knights are chosen from amongst the most fearsome and savage feral cultures, each one an emergent psyker who has undergone arduous tests of faith, strength, endurance and courage that would break all but the strongest. Grey Knights fight in baroque, heavily ornamented suits of armour, carrying mighty sigil-encrusted swords and halberds. These warriors alone can stand before the might of a Greater Daemon with any hope of banishing it back to the Warp. The millennia the Grey Knights have spent in battle against the Forces of Chaos has furnished them with blasphemous knowledge, painstakingly pieced together by the Inquisitors of Ordo Malleus. Each warrior carries a copy of the sacred Liber Daemonica, the holy battle rites of the Chapter, in a Ceramite case on his breastplate, and it is this tome which symbolises a Grey Knight’s most potent weapon: his unshakable faith in the Divine Emperor of Mankind. For above all else, the Emperor protects...
 * Deathwatch - The Space Marines of the Deathwatch are mysterious figures who battle in black Power Armour, fighting with preternatural skill and dedication against the most terrible of alien creatures or xenos, as they are called in the Imperium. They usually appear without warning and vanish as quickly as they arrived, leaving no trace of themselves or of the creatures they have fought. These are the Imperium’s most highly trained xenos fighters, known simply as the Deathwatch. Forming the Chamber Militant of the Inquisition's Ordo Xenos, the Deathwatch uniquely draws its members from across the many different Space Marine Chapters, all of which have sworn sacred oaths to maintain specially trained xenos fighters and stand ready to deploy them at a moment’s notice when the Inquisition requests their aid. These specialised warriors are drawn together as and when needed by the Ordo to combat alien menaces whenever and wherever it rears its vile head. Rumour has it that Ordo Xenos maintains a number of secret fortresses at the fringes of the Imperium where the Deathwatch keeps a silent and constant vigil, ever watchful for the tell-tale signs of alien encroachment.
 * Collegia Titanica - The Collegia Titanica is the division of the Adeptus Mechanicus that includes the Legions composed of Titans, the colossal Imperial robotic war machines that are the most powerful engines of war in the Imperium of Man. The Collegia is also more rarely known as the Adeptus Titanicus (a contraction of "Adeptus Mechanicus Collegia Titanica").
 * Sisters of Battle (Orders Militant of the Adepta Sororitas) - The Adepta Sororitas, also known as the Sisters of Battle, are an all-female division of the Imperial Cult's ecclesiastical organisation known as the Ecclesiarchy or, more formally, as the Adeptus Ministorum. The Sisterhood's Orders Militant serve as the Ecclesiarchy's fighting arm, mercilessly rooting out corruption and heresy within humanity and every organisation of the Adeptus Terra. There is naturally some overlap between the duties of the Sisterhood and the Imperial Inquisition; for this reason, although the Inquisition and the Sisterhood remain entirely separate organisations, the Orders Militant of the Sisterhood also act as the Chamber Militant of the Inquisition's Ordo Hereticus. The Adepta Sororitas and the Sisters of Battle are commonly regarded as the same organisation, but the latter title technically refers only to the Orders Militant of the Adepta Sororitas, the best-known part of the Adepta. The Sisterhood serves as the Ministorum's only official military force because the Decree Passive laid down by the reformist Ecclesiarch Sebastian Thor held that in the wake of the Age of Apostasy of the 36th Millennium, the Ecclesiarchy cannot maintain any men under arms. This was supposed to limit the power of the Ecclesiarchy. However, the Ministorum were able to circumvent this decree by using the all-female force of the Sisterhood.
 * Imperial Navy - The Imperial Navy holds nearly all of the Imperium’s fighting vessels; local governments, Warmasters and others are forbidden to maintain their own fleets of warships. Their spacecraft include some of the most potent engines of destruction in the whole galaxy, including mighty battleships thousands of years old. The Navy’s ships range from small escorts with a crew of a few dozen to the immense Emperor-class Battleships which might have 20,000 souls or more on board. The Navy also includes fighter and bomber crews and aircraft that support the Imperial Guard on the ground. The Navy’s officer class is highly traditional and aristocratic in character. The Imperium’s noble families frequently boast naval officers among their number and naval dynasties dominate many battlefleets. Elitism is a virtue on most ships, where the officers’ lives are in stark contrast to those of the ratings and engine crews. With thousands of crew living and dying on ships that can spend decades without seeing port, a ship of the Imperial Navy becomes a city in space. Mutinies are not unknown and the Naval security battalions of Armsmen are a familiar sight on the decks of all naval ships, their black visors and shotguns constantly reminding the men that obedience is their duty to the Emperor. The Navy relies on many other organisations to function. Perhaps most importantly, these ancient and complex ships could not function without a complement of Tech-Priests who know how to appease the starships’ Machine Spirits and maintain technology that is too old and mysterious to be replicated. The Navy is also reliant on the Tech-Priests of Mars for refits, upgrades, repairs and new starships. It is usual for a warship to have Astropaths on board, for proper communication is essential if the Imperium is to be defended. Many captains are glad to have Ministorum clergy among their crew, ministering to the spiritual needs of the men and steeling their spirits with sermons. Commissars are appointed to the larger ships, watching over the moral fibre of the crew and providing a watch against mutiny and impiety. Then, of course, there is the Navigator of each vessel, whose family can occupy entire spires jutting out into space atop the ship.
 * Skitarii, the Legio Cybernetica and squads of Combat Servitors - These are three types of autonomous military ground forces deployed the Adeptus Mechanicus to protect their Forge Worlds and to assist Imperial military campaigns when necessary.
 * Inquisitorial Storm Troopers - The Inquisition maintains its own own corps of highly-trained special operations forces who are similar to the Imperial Guard's elite Storm Troopers that guard the secret installations of the Inquisition across the galaxy. The Inquisition maintains a number of fortresses throughout the galaxy, both secret and known to the inhabitants of the Imperium. Inquisitorial Storm Troopers are used by the Imperial Inquisition to guard their fortresses and the Black Ships as they make their purity runs across the Imperium's sectors, and they also augment an individual Inquisitor's personal forces with reliable and effective soldiers. Many Storm Troopers of particular skill are chosen to become an Inquisitor's Throne Agents. Inquisitorial Storm Troopers are selected from families with a record of unwavering faith in the Emperor and prior duty to the Inquisition, usually from the Schola Progenium. They are trained and equipped in a manner similar to Imperial Guard Storm Troopers, albeit lacking the rapid insertion and infiltration skills, as they are not expected to undertake such types of missions which are more often carried out for the Inquisition by the Officio Assassinorum.

Imperial Cult
The Imperial Cult is one of the few common factors that link the disparate worlds of the Imperium together. No matter what conditions prevail upon a world within the Imperium, the Imperial Cult will be found there. The ways in which the Emperor is worshipped in human space are multitudinous. To some He is revered as a distant, patriarchal and human figure. Others identify Him with some aspect of nature, many others, such as the primitive Epheisians of Dwimlicht, regard Him as a Star God, for His agents only visit occasionally and they descend from the heavens when they do so. But all the creeds of the Cult agree upon this one thing: there is only one Emperor. To worship a pantheon of Gods and put other Gods alongside Him is heresy. However, there have been many individuals over the millennia who have been seen as His saints, people visibly touched by the Emperor, and they are venerated all over the Imperium. There are saints for every aspect of life and there is a thriving trade in their relics on many worlds.

The worship of the God-Emperor is, in the main, highly organised across the Imperium. Cathedral complexes can be found in the capitals of all worlds of any meaningful populations. On the densely populated, teeming hive worlds, these can occupy entire spires. The graceful structure of the Cathedral of the Emperor Triumphant, constructed after the Second War for Armageddon at Hive Primus on Armageddon, climbs delicately skyward, its main tower nearly a full kilometre in height. The statue of the Emperor at the top brushes the planet's troposphere, looking benignly down upon the seething, polluted Hive World below. Most towns will have a church or temple dedicated to the Emperor and even the crudest village of the most primitive tribesman will sport a sacred cave or grove dedicated to his name. Of course, in some places, the worship of the Emperor supercedes all other aspects of life—these are the Shrine Worlds of the Imperium, where perhaps one of the great saints, or even, in the distant past, the Emperor Himself, performed a great deed.

These planets can be one, vast, religious complex, or huge cemetery worlds such as Granithor, where the wealthy spend vast fortunes bringing the dead scions of their families for burial, usually those who have perished in the service of the Emperor. Then there are the Cardinal Worlds, which attract millions of pilgrims and are the strongholds of the Cult. These planets are directly governed by the Ecclesiarchy and are the seats of functionaries high in the Cult, responsible for the spiritual health of vast areas of human space. The Ecclesiarchy maintains and promotes the Cult galaxy-wide and, where possible, tries to sanction the worship of the Emperor no matter how bizarre it may seem. Very few practices are proscribed, and even such abominations as human sacrifice to the Emperor are useful to the Imperium, for it is easy to convince a newly encountered culture that approves of such custom to give up its psykers to the Black Ships.

One of the Ecclesiarchy’s tasks is to record this multiplicity of tradition with which the Emperor is honoured. In that way, two Preachers from opposite sides of the galaxy will know, no matter what their title or manner of expressing their devotion might be, that neither is a heretic. The Ecclesiarchy sends out mission fleets for precisely this purpose, whose flotillas of blessed spacecraft slowly circle a particular part of the galaxy, recording new variants of the Cult, correcting serious heresies and proselytising to newly discovered populations of humans. To all, the Emperor is a living God. He may be tens of thousands of light years away, but that He exists, the inhabitants of the Imperium know, so faith is an easier thing in the 41st Millennium than it has been at other times in human history. Some amongst the Ecclesiarchy and Inquisition may argue that men should be more ardent in their devotion to Him, but though some may be lax in their adulation and may blaspheme or heretically curse the Master of Mankind for their lot, it is nevertheless rare to meet a man who would dare to deny the Emperor’s divinity.

The Ecclesiarchy presides over the souls of the Imperium’s citizens, dividing its countless dioceses into parishes, some of which are centred upon a particular planet, others focused to tending to a particular locale or holy shrine. Each parish is ministered by a priest called a Preacher, seeing to the well-being and purity of his flock’s souls. It is their duty to watch for deviancy and ensure that heretical belief is purged wherever it lurks. A truly pious Preacher may rise to become a Pontifex, whose authority extends over several parishes and their Preachers. The responsibilities of a Pontifex are diverse and can encompass the protection and ministration of routes of pilgrimage, the consideration of beatitudes and recommendation of canonisation to the holy synods. The priests called Confessors are the booming voices of the Ecclesiarchy, exalting the faithful to deeds of penitence, fervour and righteousness. Confessors are not charged with the ministrations of a diocese, but rather roam the Imperium at-will wherever the hand of the God-Emperor calls them. Under the spell of a Confessor a city can burn at the hands of its own citizens, armies may jubilantly throw themselves into the waiting guns of an enemies’ hands and heretics flee, fearing their holy wrath.

Cult Mechanicus
Technology and its mysteries are the preserve of the followers of the Machine God, the Tech-priests of the Cult Mechanicus. For they believe that machines are imbued with a life-force of their own, a soul granted to them by the Machine God who governs the universe—a will and a personality. The more ancient a piece of technology, the greater reverence it will elicit from these robed followers, who will spend many hours anointing a machine with the correct unguents before pressing the sigils of activation to coax its animistic Machine Spirit into life. The God-Emperor of Mankind is the Omnissiah in this view, the physical embodiment of the Machine God in realspace.

A machine that is both old and complicated is given the same status by the Tech-priests as the Ecclesiarchy would give a major saint, for many of the systems on these machines are irreplaceable, their secrets lost to time. Among the greatest of such machines are the vast Battleships of the Imperial Navy, or the super-heavy Titan war machines. But the Tech-Priests will also lavish their attention upon an antique Lasgun or prognosticator and will spend much time trying to understand the intricacies of a device’s workings. All machines though, no matter what their pedigree, are treated as living things by the Tech-priests and they will treat all with reverence, for all are gifts from the long-lost past, knowledge of their function handed on through time only by the beneficence of the Machine God. Woe betide any man who fails to treat his weapon with respect or hurls abuses at his desktop logicator within the range of the cybernetically-enhanced senses of a Tech-priest.

Paradoxically, true machine intelligences are held to be anathema by the Tech-priests, for they view these as soulless automata, spiritless things cast into the galaxy to confound the will of the Machine God. Shrouded in myth and legend, these abominations are rumoured to have originated during the Dark Age of Technology and to have caused immense damage to the interstellar human civilisation had existed before the Age of Strife brought it low. Supposedly pathologically dangerous, an Inquisitor may encounter them, although rarely, in the course of his duties. Should they learn of these creations, the Tech-priests will hunt them down, investigate them and then destroy them. Only properly sanctioned digital logic engines and Cogitators, those deemed to have a spirit gifted them by the Omnissiah, are allowed to persist.

The Imperial Demesne
The territory of the Imperium is defined by the reach of the psychic beacon of the Astronomican, which has a range of approximately 50,000 light years. The Imperium proper could thus be thought of as a sphere whose center lies at Terra's Sol System, and whose radius is about 50,000 light years wide. However, as a practical matter, agents and agencies of the Imperium (along with "unofficial" representatives of the Imperium - such as Rogue Traders - who often work in tandem with the goals of the Imperium) carry on its affairs and expand its influence beyond that limit. The disparate and widespread nature of Imperial territory, with its millions of star systems and worlds, means that a strongly centralised government would be unfeasible.

The Imperium encompasses countless worlds. No one has ever been able to map them and no one can even say how many there are. Entire departments of the Adeptus Administratum are devoted to cataloguing the worlds in the Emperor’s domains, a never-ending task, for it is in a state of eternal flux. Furthermore, the Adeptus Terra holds that the whole human race and the entire galaxy are under the Emperor’s rule—the Imperium has a manifest destiny to unite Mankind, impose its laws on every human world and destroy all alien life. The true scope of the Imperium is, therefore, the entire galaxy, though this is far from actuality. The Imperium jealously guards its territory whenever it can but its sheer size means that it cannot react to every circumstance. Many planets live and die alone, with only the truly great threats commanding the attention of the Adeptus Terra. Worlds are frequently lost to aliens, rebellion or disasters, with news of their destruction sometimes taking centuries to reach Terra. The Imperium’s borders undergo constant change, with new worlds discovered, conquered or colonised and old ones lost to xenos attack, Exterminatus or even to the Warp.

The Imperium of Man divides the galaxy into five administrative zones called Segmentae Majoris, which include the:


 * Segmentum Solar, the galactic "center," with the Sol System at its heart.
 * Segmentum Pacificus, the galactic "west."
 * Segmentum Obscurus, a region to the galactic "east" of Terra that has been heavily fortified by the Imperial Navy and the Imperial Guard due to the dangers posed by this Segmentum's most infamous element, the Eye of Terror. This is a vast Warp rift where the Immaterium actually intrudes upon material space - as do the Chaos Space Marine Traitor Legions and the daemons of the Ruinous Powers themselves.
 * Segmentum Tempestus, the galactic "south."
 * Segmentum Ultima, the largest province of all in the Imperium, located to the galactic "north" of Terra; its furthest extents are beyond even the range of the Astronomican in space still unexplored by humanity.

The Segmentae are the primary administrative divisions of the Imperium. Each is divided into sectors, which are areas of three-dimensional space. The sectors in turn consist of sub-sectors, each containing a number of individual star systems. These spatial divisions and subdivisions are also levels of the administrative hierarchy.

Each Segmentum Governor (or Segmentum Commander, the term used when the governor is acting in his military capacity) oversees his Sector Governors (or Sector Commanders), who in turn oversee Sub-sector Governors (or Sub-sector Commanders), who in their turn oversee the individual Planetary Governors, who are also known as Imperial Commanders. The higher ranks in this administrative system are usually combined with a basic planetary governorship as well as interstellar duties. Each of these governors is usually a member of the Imperial nobility and it is rare, but not impossible, for a man or woman born in the lowest ranks of Imperial society to rise to the rank of an Imperial Governor on his or her own merits or abilities. This neo-feudal system is the means by which the Imperium maintains control of the separate planets that comprise it.

Planetary Administration
Because of the distances involved and the unstable nature of Warp communication, Planetary Governors generally operate very autonomously. This allows quite a lot of variation in the regional governments of the Imperium. Some governorships are hereditary, but it is also possible for a planet to have an elected Planetary Governor, a tyrant Governor who rules solely by force of his personal arms, or anything in between. So long as the Governor fulfills his duties to the broader Imperium, his rule will generally be accepted by the higher authorities with little or no interference.

A rare few Planetary Governors preside over Feral or Feudal Worlds where the Imperium has not, for whatever reason, seen fit to introduce modern technology. These Governors are often isolated from their subjects, sometimes even living on orbital installations, only interfering to control mutation, Chaos incursions, Ork invasions and rogue psykers, as well as to collect the modest tithes in men for the Imperial Guard and psykers that these planets provide. The Imperial duties of a Planetary Governor include paying the planetary tithe to the Administratum, controlling psykers, mutation and heresy among the population, defending the planet and putting down rebellions against the local government (and thus against the Imperium). A serious responsibility for a Planetary Governor is the maintenance of an adequate planetary defence force capable of defending the planet in the event of an invasion. The Planetary Defence Forces (PDF) are expected to defeat attacks from minor foes, and in the case of major invasions to hold out until reinforcements arrive, which could take a period of months, years or even decades.

A relatively small number of Imperial worlds are not ruled by a Planetary Governor, but are directly overseen by an alternate organisation such as the Adeptus Terra, the Ecclesiarchy, an Imperial Commander of the Imperial Guard or a Chapter of the Space Marines. These planets include the Forge Worlds of the Adeptus Mechanicus, whose inhabitants toil without pause to manufacture the weapons of the Emperor's armies (including Mars, Gryphonne IV and Fortis Binary), the Cardinal Worlds of the Ecclesiarchy, which are given entirely over to education of the priesthood and worship of the Emperor (Ignatius Cardinal, Ophelia VII), and the Space Marine Chapter homeworlds, such as Fenris, Macragge, Baal, or Medusa.

Just as the environments and cultures of Imperial worlds vary immensely, so too does the way they are governed. The Imperium allows most of its worlds to govern themselves, using whatever method of government the population gravitates towards or was the traditional form of rule. Some are hereditary monarchies, others are ruled by aristocracies or warlords. Some are ruled by elected parliaments, while on others power is given to whoever can pay for it. On some worlds these are the same thing. Upon other planets, such things as democracy, free choice and even individual civil rights are present, though these worlds are few and far between. Some worlds are administered directly by the various Adepta, such as Agri-worlds run by the Administratum or Cardinal Worlds ruled by the Ecclesiarchy. Whilst the individual countries, states, tribes, corporations, hegemonies, peoples’ work collectives, and so on, may have their own various leaders, the Adeptus Terra will look to one person to fulfil the planet’s Imperial tithes and obligations to the Imperium. Titles for this governor vary from planet to planet. In some cases the person judged responsible for the Imperial tithe may not even be aware that this is the case until too late. Certainly, more than one titular head of state has discovered this upon rejoining the Imperium after a period of isolation through Warp Storm, war or other calamity.

All Imperial Governors are expected to recognise the authority of the Imperium and the Emperor and to uphold His laws. These responsibilities include aiding the agents of the Adeptus Arbites and the Inquisition, as well as arranging the allotted tithes for the Administratum. Governors are also expected to yield psykers up to the Black Ships of the Inquisition when required and to keep the population free of mutants, Chaos Cultists, heretics, political radicals and witches. In practice, some planets escape from these duties with relative ease, whilst others are placed under seemingly tyrannical restrictions. Due to the sheer size of the Imperium and the unpredictability of travel through the Warp, there are many occasions where the Administratum never manages to extract its levy, or the Black Ships never arrive at the appointed time to take psychic individuals away. Planets can be isolated for generations and it is not unusual to encounter worlds where the Imperial tithe has been all but forgotten. Certainly the scribes of the Prol System have, in their vast libraries, several accounts of Administratum Logisters arriving at worlds lost for centuries, only to discover their yearly tithe burning on vast pyres as the natives offer their dues up to the sky.

In some cases, a group of planets might have enough contact with one another to form political alliances and even minor interstellar empires. Other clusters of worlds might be connected by huge corporations, the powers of hereditary nobles, religious leaders or other such ties. In such cases, Planetary Governors must not only tend to the needs of the Imperium but also the whims of these power blocs.

Human Variability
The peoples of the Imperium vary in their form and appearances just as their homeworlds do. Whilst there is a generally agreed baseline human standard, consisting of four limbs, one head, twenty digits and so on, the local environment and genetic stock have caused all manner of interesting anomalies, evolutionary adaptations and fashions. These differences are usually cosmetic in effect; however, the more radical alterations walk the line between accepted variation and outright mutation. It is a subject of intense debate amongst some Inquisitors, and indeed the priests of the Ecclesiarchy, on what it is to be human and therefore accepted into the Imperium.

Certain planets will betray their colonial origins with the appearance of their peoples—perhaps a particular type of nose or skin colour will be dominant. Others will have clear tribal divisions. Some populations will possess unusual adaptations as a consequence of their local environment. The folk of the Agri-world Dreah, for example, have a grey skin, hair and eye tone, which exactly matches the flora, fauna, sky and waters of their notoriously dull planet. Some cultures may impose certain ideals of beauty that drastically alter the looks of their peoples. Certainly, many strange and terrible gangs of Underhivers have been discovered, clad in hyper-fashionable armour, sporting glowing electoos, skull studs, gang tribal mutilations and shiv scars with pride.

To some extent a similar appearance and culture binds the people of a planet together into a common stock. Usually speaking, citizens of the Imperium will prefer to spend their time with fellow natives of their world. That said, however, Mankind has ever been titillated by the exotic, so friendship, love affairs and even children with off-worlders is not unknown on planets with a culture that legitimises such travel.

Rebellion
The Imperial Creed maintains that all of humanity must be brought and kept within the Imperium where men and women can benefit from the rule of the Emperor. Several Imperial organizations are permanently occupied with suppressing any possibility of rebellion before it has a chance of developing. The common worship of the God-Emperor holds mankind together and instills loyalty towards the Imperium. Rebellions and uprisings on Imperial planets nonetheless remain a constant problem. The nature and causes of a rebellion can fall into several categories: the government of an Imperial world may decide to secede from the Imperium; a popular uprising may attempt to overthrow the local Imperial government; in the most insidious of cases the rebellion may be brought about by alien or Chaos influence. In the more prosaic cases however, a government established through rebellion is not necessarily opposed by the Imperium, so long as it accedes fully to Imperial authority and pays its tithes to Terra. Besides the pursuit of outright war, there are many ways a rebellious world may be brought back into the Imperium. With the existence of its more secretive organs like the Inquisition, the Imperium is fully capable of carrying out covert methods of restoring Imperial rule, including assassination, popular agitation, economic sabotage and terrorism. Sometimes a rebellion can be subdued by the removal of a single individual. Pro-Imperial groups or other anti-government forces can be infiltrated or supported as required.

Imperial Languages
Low Gothic is the common tongue of the Imperium, spoken on most Imperial planets as a first or second language. Imperial worlds have inevitably developed their own, often highly variant, dialects of Low Gothic over time. High Gothic (represented as a form of Latinised English) dates from the last time humanity was united across interstellar distances in an ancient confederation that existed during the Dark Age of Technology (long before the Age of the Imperium), and is used solely as a hieratic tongue by the divisions of the Adeptus Terra, the Inquisition and the Ecclesiarchy. Low Gothic (also called Imperial Gothic or simply Gothic) is the “official” language of the Imperium, the everyday tongue of its Adepts and of Terra. Most worlds have been a part of the Imperium for long enough to have adopted Low Gothic as a universal tongue but there are still a great many Feral Worlds on which Imperial Gothic is not spoken. Inevitably, dialects of Gothic differ from world to world and can be mutually unintelligible. Older planets frequently maintain archaic tongues of their own, to the extent that ruling aristocracies might only know enough Low Gothic to be sworn into their Imperial offices. For highly formal matters, the Adeptus Terra use High Gothic, the precursor language of Imperial Gothic. Many Ecclesiarchy rituals, Administratum edicts and Imperial charters use this ancient and venerable language.

Psykers in the Imperium
Humans with psychic powers, known colloquially as psykers, who possess abilities ranging from telepathy to pyrokenesis, have existed since the dawn of Mankind's existence as a species during the Paleolithic Age on Old Earth, but their position in the Imperium is an uncomfortable one at best. An untrained psyker is an unguarded gateway to the Warp, through which psychic predators like daemons and Enslavers can enter realspace and wreak havoc. It is said that whole worlds have been lost to hideous monsters of the Empyrean, while rogue psykers have committed horrible crimes with their powers or led dangerous and destructive cults. On some worlds all psykers are tried as "witches," subjected to tortuous ordeals and burned at the stake when their inevitable guilt is proven. Imperial law requires all worlds to monitor its psykers and subject them for testing by the Adeptus Astra Telepathica. Those who are strong enough to withstand the perils of the Warp are forced to endure the soul-binding and are trained to serve the Imperium as Sanctioned Psykers. Those who are too weak are taken away by the Black Ships and never seen again, their lives used to maintain the Emperor's strength within the Warp.

Travel in the Imperium
Interstellar travel between the worlds of the Imperium is rare and dangerous. The vast majority of civilians will never know the roaring tedium of shuttle flight, the sickening plummet of a Drop Pod or the unnerving silence of deep space. Given the huge size of the Imperium, it is impossible to cross it in the fleeting span of time given to ordinary men. Colonists, pilgrims and refugees spend many generations in the vastness of space, and many starships never survive the vagaries of travel to reach their destination.

Sub-Light Travel
Used mostly for journeys between planets or closely neighbouring star systems, sub-light travel involves speeds that confound mortal imagination and yet are still nothing when measured against the sheer size of the galaxy. Those attempting to use slower than light drives to travel any appreciable distance condemn themselves and their descendants to a shipboard life, endlessly whittling away the years until they arrive at the distant star they set out to reach. The average Imperial citizen is unlikely to experience slower than light space travel. Even those individuals living within a system with plentiful ships for interplanetary travel are likely to prefer the world of their birth over distant places with strange customs, odd food and “funny-looking” people. In many places, space travel is reserved for the privileged few who can afford to maintain the rituals, priests and shrines that such craft require, as well as the vast cost of the starships themselves. Tech-Priests do what they can to sate the Machine Spirits of these spacecraft, but often even their unfathomable lore is not enough to prevent these temperamental ships from venting their rage (and oxygen) to the detriment of passengers. Sheer odds dictate that sooner or later those that frequently travel in ships between planets will experience such a disaster. Those worlds that have not lost the art of creating and maintaining slower than light starships jealously guard their arcane craft. This reluctance to share their guild secrets ensures the reliability and price of their vessels but also robs others of vital information required to placate their own craft. Institutions such as the Imperial Navy, the Inquisition and various Adepta have access to much better-quality vessels, maintained with religious awe and reverence by countless generations of the Adeptus Mechanicus.

Warp Travel
"For the Warp is a strange and terrible place. You might as well throw a traveller into a sea of sharks and tell him to swim home as send him through the warp unprotected. Better it is not to let common man travel through the stars. Better still, let him now know such a thing is feasible."

- Fra Safrane, 5th Aide to Navigator Da'el. Comment made prior to the departure of the second mission to search for the missing freighter Pride of Angelus To move any appreciable distance within the Imperium, voyagers must make use of Warp travel. This method of faster than light travel is rare, expensive and dangerous, as it requires the use of the unpredictable realm known as the Warp, or the Immaterium. Vessels equipped with a functional Warp-Drive are able to translate themselves into this other dimension of being by generating an envelope of protective Gellar Fields. The Warp-Drive “bends” the starship through the veil of realspace into the Immaterium. Once within this strange hyperdimensional realm, the starship is able to ride the currents and eddies that flow within the Warp, frequently dropping back into realspace to check its positioning.

The Immaterium is a bizarre and contradictory place, entirely unnatural to Mankind or any being of realspace. Looking upon the Warp unprotected causes madness and Chaotic corruption, and thus is greatly feared by almost everyone in the Imperium. Dimensions, colours, forces and emotions operate entirely differently within the Warp’s embrace, and this can drive even the most thick-headed crewman insane. Psykers of course, find such travel even more disturbing as their mystical senses are able to comprehend much more of the Immaterium and the foul creatures that dwell within it. Those that travel through the Warp emerge to discover another of its disconcerting effects. Time does not operate normally within this other realm and so travellers can emerge to discover that centuries have passed in realspace since they started their journey, that they have merely been absent for a few seconds, or have even arrived before they left. Even skilled Navigators cannot predict how much time will be lost, gained or repeated over the course of a journey. Those that embark upon Warp travel know that they will probably never return home, or that if they do so they will find it so changed that it is unrecognisable. When two or more captains of starships meet, they invariably trade dates, attempting to reconstruct the time they are missing or have gained. Needless to say, Warp travel is not embarked upon lightly.

The Warp is occasionally prone to great turbulence or storms of activity. These strike at random and last for an unpredictable amount of time. Whilst these Warp Storms rage, any vessels within are tossed about on roiling currents, sometimes being spat out at random locations. Other ships simply become trapped, unable to translate back into realspace, cursed to an eternity upon the waves of the Warp. These storms disrupt communication across the Imperium and can sometimes herald a great disaster within realspace, as they did during the Age of Strife before the birth of the Chaos God Slaanesh during the Fall of the Eldar.

Imperial Communications
Just as travel within the Imperium is a complicated and inexact science, so too is the business of exchanging messages between the many and varied planets that make up the Imperium. Planetary communications systems such as vox-casters, hardwired telegraph and telephony lines and the more advanced vox-communicators suffice to pass messages amongst the nations of a world, yet have almost no use beyond the bounds of the planet’s surface. Such devices require many Terran years for their signal to reach even the nearest planet of a star system and have no surety of even being detected when they arrive. The perils of travel ensure that human or Servitor messengers are just as unreliable and potentially as slow as radio or other energy wave communications.

The Imperium is forced to rely upon communication by psychic, or astropathic means. Astropaths communicate with symbols and iconic images, projecting these messages through vast distances of space by means of psychic power drawn from the Warp. This process is usually exhausting and requires ritual and focus in order to keep the psyker in the right frame of mind. These can take a wide variety of forms, such as use of the Emperor's Tarot, vision quests, automatic writing, trances, séances and the like. The Gaolist Astropaths of Hredin for example, spend many years etching their messages onto painstakingly illuminated sheets of iron and then destroy the work of art upon a massive grinding wheel when they are ready to transmit the information. The pain of annihilating a much-loved labour is said to produce psychic messages of unparalleled clarity.

These messages are received by fellow Astropaths in various ways. Some appear as vague and troubling dreams, whilst others appear as visions or mystic portents. Others appear within whatever ritual method or divination technique the receiving psyker happens to practise. Thus warning of an Ork invasion might appear as a glistening imperfection in fish entrails, a looming cloud of smoke, bleeding orifices or a worrying combination of runes or sigils within a holographic matrix. Astropathic messages must not only be transmitted from one Astropath to another but decoded at the other end. Each Astropath employs slightly different symbols and each has a preferred style or “flavour”. Some messages take weeks of poring over tomes of augurs and symbolism before they can be reconstructed, though the best Astropaths can do this word for word. Some remain a mystery forever. Some messages are received by Astropaths at entirely the wrong end of the galaxy and must be passed on to others who are nearer the place in question.

Some messages simply do not get to their intended recipient or are drastically misinterpreted along the way. In addition, there are too few Astropaths. Most worlds, especially those with small populations or on the fringes of the Imperium, have no Astropaths at all, and must rely on the infrequent visits of passing Chartist ships or Administratum census-takers to make contact with the outside galaxy at all. For this reason the Adeptus Terra cannot react quickly to every event in the Imperium, even when an event occurs that is great enough to attract the notice of the vast and ponderous bureaucracy. On most worlds, the Imperium feels very far away.

Imperial Calendar
The Imperium of Man uses a special Imperial Dating System derived from the original Gregorian Calendar of Old Earth that denotes the current year by the notation &lt;year of the millennium&gt;.M&lt;millennium&gt;. For example, the year 40,999 AD would be represented as 999.M41, while 41,002 would be 002.M42 and the year 2010 would be 010.M3. However, the year 41,000 AD would be 000.M41, since the new millennium starts at the year 001 and has no Year 0.

Threats to the Imperium
Despite being the largest empire that humanity has ever known, many planets within the Imperium feel isolated and alone in the deep void of space. Across all the peoples and planets of the Imperium, fear gnaws away at the psyche, worming mistrust and desperate faith into the conscious and unconscious mind. Time and again the universe has proved itself an uncaring and frightening place deeply hostile to the survival of humanity. People fight one another, the Warp rages, xenos attack and worlds die. The people of the Imperium watch their neighbours for signs of heresy and witchery. Mankind prays to the Emperor to protect them from the woes of the universe, of which there are many.

Dark Gods and Daemons
Time and again throughout history, the minds of Man have proven fertile soil for the seeds of corruption by Chaos. There are certain dark powers abroad in the universe that seduce the weak and foolish into their damnable service. These ageless beings, their names unspeakable, prey upon Mankind’s needs and desires. With honeyed words, forbidden knowledge, bloody rites and festering secrets they lure humanity to become their slaves. Some within the Imperium choose to worship these Daemon Gods. The ways of these Chaos Cults are many. Some meet in clandestine rituals of sacrifice and incantation. Others are foolish scholars, meddling with powers beyond their ken. Others still are organisations, companies or political groups drunk with power gained through pacts with unspeakable creatures of the Warp. Perhaps worst of all are the instances of entire worlds that worship the Chaos Gods through ignorance or choice. All of these profane cultists invite ruin upon themselves, the Imperium and humanity. The Adeptus Terra, Planetary Governors and the Inquisition all watch for these disciples of Chaos, for the inevitable consequence of their meddling is pain, disaster and bloodshed. The ordinary peoples of the Imperium rightly fear these cults and their malevolent masters. On many worlds an undercurrent of paranoia, suspicion and fear of Chaos Cultists is the norm.

The very existence of such fell beings as the daemons of the Warp is a terrible secret to most citizens of the Imperium, as the Imperium's rulers believe such truths must be hidden from the minds of those who would fall prey to them. A daemon is a Warp entity, a terrible creature of thought and psychic energy brought forth into existence by the twisted needs of sentient beings, or at least so the high masters of the Ordo Malleus say. To even think of them is to invite their attention and only the steeliest mind, the most powerful faith in the God-Emperor, is enough to overcome their utter, monstrous evil. Inconceivable as it may seem, there are those who would consort with the daemon, for they whisper dark things in the night to those who would listen and make many promises of temporal or eternal power. They can be brought forth willingly, by the witch or by certain arcane sorceries, or they may try to force a way through into realspace through the unsuspecting portal of an untrained psyker’s mind. However they become incarnate, if they achieve their goal, just one daemon can bring ruination to all it encounters. One need not talk of the Night of Silence in Atraxian III’s capital, nor of the lost world of Abandoned Hope, which to this day is warded by the Inquisition, knowledge of its existence forbidden to all. Make no mistake, to face a daemon is to face damnation, to court a daemon is to embrace its dark masters.

Mutants and Witches
The degeneration of the holy human form is one of the Ecclesiarchy’s greatest concerns. Environmental pollution, deliberate genetic alteration, stellar radiation, alien diets and simple evolutionary adaptation have wrought manifold changes upon the genome and body of Man across his vast stellar empire. Some of these mutants have a standard, stable, morphological type and are tolerated by the authorities—notable among them being the Abhuman Ogryns and the ancient and nobleNavigators. But to find whole worlds where the human population has no eyes due to never-ending darkness, or unusually long legs because of millennia of nomadic living, is not unusual. Whether these aberrant populations are declared acceptable or not is the business of the Adeptus Terra.

But mutation can also be a sign of the influence of the Ruinous Powers of Chaos. Just as they twist and destroy the minds and souls of Man, so too do they toy with his flesh, bending it into profane shapes, gifting strange abilities and creating monsters for their perverse amusement. Where such mutation is present, it is rightly abhorred. Few are willing to tolerate such a aberation within their midst and fear of mutants runs through the populations of many worlds, even those where such things have happened but once in a hundred generations. Perhaps worse still is the constant fear of becoming a mutant oneself. Many folk pray that should this worst of all things occur, they will have the strength to end their own lives, before the mob or the Inquisition does it for them.

Some poor fools are willing mutants, seeing the distortion of their flesh as a sign of favour from the Ruinous Powers. They seek out ways to gain more of these mutational "gifts," either by begging the Dark Gods for more of their touch or by doing their bidding in the hope of further reward. Others, more poignantly, claim innocence of any wrong doing or foul worship. Whatever the case, a mutant is a mutant and must be feared, hated and destroyed. This is but one of the many reasons Imperial citizens tend to be highly intolerant and many innocent men, upon finding themselves on a new world, have been murdered by a frenzied mob for merely appearing to be different.

The related question of witchcraft also exercises the minds of a great many of the Emperor’s servants. Indeed, one whole arm of the Inquisition—the Ordo Hereticus—has the finding and destruction of these dangerous beings as one of its primary activities, and several other organisations exist to contain, exploit and control these human psychics. It is said by a heretical few that Mankind stands upon the brink of a great evolutionary change in the species, that every year the incidence of psykers rises and that one day the entirety of Mankind will become a new, psychic race much like the Eldar.

True or not, the psykers of the Imperium are a double-edged sword. On the one hand, they enable the continued existence of the Imperium—the Astropaths, the Navigators, Imperial Sanctioned Psykers, the savant Primaris Psykers of the Imperial Guard, the Librarians of the Space Marines, even the Emperor Himself—these loyal, good and necessary servants of Mankind are psykers all. Yet they are few in number and for every mind that is strong enough to stand against the perils of the Warp, there are hundreds of others whose minor gifts, whether they seem a boon or a burden to the individual, are a clear danger to the worlds of Man. The employ of their talents can lead to intrusions into the physical universe by Warp entities or leave the individual open to manipulation by certain strains of perfidious xenos. By far the most dangerous are the witches, those who revel in their abilities and seek to use them in a personal quest for power. Alone, they can wreak untold havoc, intentionally or unintentionally. It is for this reason that, of all the threats from within, the populace fears the witch most. It is a hidden danger that can spring up unbidden even inside a man’s own family, and parents dread the birth of a witch child above all things. All psykers must be given over to the appropriate Imperial body or be purified by death. Those psykers that appear to have evaded the tithe-men of the Black Ships, by accident or design, are guilty until proven innocent and the cleansing flame is their only fate.

Xenos
"Fear The Alien. Hate The Alien. Kill The Alien."

- The Imperial Infantryman's Uplifting Primer (Damocles Gulf Edition)

The Imperial Cult teaches that it is Mankind’s manifest destiny to rule this galaxy. The Ecclesiarchy holds that it is the Emperor’s will that Mankind and Mankind alone will bestride the stars, and to that end most Imperial servants fervently bend their lives. There are many other creatures in the galaxy, unclean creatures born of worlds far from the sacred soil of Terra, whose misbegotten forms are an insult to those who wear the shape decreed by the Lord of Man as fitting and right. Some of these creatures are weak and harmless, and easily extirpated, their planets expropriated for the true masters of the stars, their memory expunged. But there are other, stronger alien races that would see the will of the Emperor foiled and Mankind cast down.

Among them are the savage greenskinned Orks, whose numberless multitudes plague the galaxy with their endless desire for war. Hulking creatures, bigger than a man, they are mindless, yet powerful and unafraid. Elsewhere can be found the fickle Eldar, those who cannot be trusted, beings which extend the hand of friendship whilst clasping a dagger behind their back. Beware these fiends; their machineries of war are as swift and as deadly as their lying tongues. Likewise the Tyranids, blasphemous monstrosities who reduce worlds to bare rocks in their feeding frenzy, their endless armies made up of hellspawned bio-constructs.

Other things dwell in the dark places of space—the Hrud, whose very presence is poison to the rightful progression of time; the Tau, whose heretical technicians enslave technology to their grotesque ends with no thought for the proper rites; the Verminthiculians, wild alien mercenaries and reavers. Yet, while the alien is legion, the Imperium claims that Man is always the stronger, and the warmongering of xenos races is but the desperate savagery of those who know that their end draws near.

Heretics and Traitors
The Imperium is the only rightful authority of Mankind, as has been decreed by the Emperor, and His will, executed by the Adeptus Terra, is absolute. But Man has ever been a fractious and fickle creature and not all agree that the Emperor's rule is to be desired. Therefore the rule of Terra must, by necessity, be harsh. The size of the Imperium means the grip of its governance must be loose, and rebellion is only regarded to have taken place when one of the various Imperial tithes goes unpaid. Worlds which rise up to shake off the benevolent hand of the Emperor fall into one of the following four categories:
 * Governmental Revolt: Occasionally the ruling body of an Imperial world might misguidedly decide that their planet would be far better off outside of the Imperium. They might not have been visited for a thousand years or the Planetary Governor may harbour territorial ambitions of his own, but whatever their motivations, the result is the same—ruthless and immediate repression. These revolts must be dealt with swiftly and graphic examples made of the ringleaders, for if just one planet is shown to succeed in such a quest, others will certainly follow. It may take centuries to quash a revolt, but no human world is ever allowed allowed to secede for long from the Imperium. Assassination, planetary assault and, occasionally, Exterminatus are all righteous tools that may be employed to bring the wayward world to heel.
 * Popular Revolt: It is a regrettable fact that many citizens of the Imperium suffer from the most horrendous living conditions in less-than-ideal environments. From time to time, a particularly bold demagogue may rally his fellows and overthrow a planetary government. This only becomes a problem if they then go on to defy the authority of the Imperium, otherwise the new regime will go unmolested—it is ordinarily not the Adeptas' way to impose a specific governmental form upon a population. Foolishly, flush with success, the rebellious people of a world often go on to do just that, mistakenly identifying the Imperium with their oppression and not their salvation. Also, it is sometimes better on planets with a particular strategic importance to ensure continuance of a specific form of governance. In both these cases the military forces of the Imperium are brought to bear.
 * Xenos Infiltration: There are many creatures in the universe that exist by using other creatures as their proxy. These may be creatures from the physical realm, such as Genestealers, or beings such as the Enslavers, who somehow have a material being but dwell within the Empyrean. Sometimes these worlds carry on seemingly as normal, the rest of the galaxy unaware of the dark, alien cancer eating at their heart. As often as not, the alien-dominated population will rise up in armed rebellion. In either case, utter destruction of the infested inhabitants is, regrettably, the best course of action. This can be effected via Exterminatus, through tectonic destabilisation, the use of Cyclonic Torpedoes or viral (general or geno-tailored) bombardment, dependant upon the importance of the world and the possibilities for subsequent recolonisation.
 * Daemonic Infiltration: A planet may turn to worship of the Dark Gods under a number of circumstances. Suppression of such revolts must be handled carefully—destruction of the population may be the Ruinous Powers’ actual aim, as the psychic feedback in the Immaterium caused by the sudden deaths of millions of people can be enough to permanently open a rift between the Warp and realspace. Planetary invasion by specialist formations like the Space Marines or the Grey Knights is advisable, followed immediately by planetary cleansing or destruction through Exterminatus.

Other Science Fiction Influences on the Imperium of Man
The Imperium itself, in keeping with the dystopian themes of Warhammer 40,000, is a highly oppressive techno-theocracy obviously influenced by the Padishah Empire found in Frank Herbert's Dune. It also closely resembles Isaac Asimov's Galactic Empire in the Foundation series, with millions of star systems only loosely connected with the governing center, where technology is becoming a myth rather than a science, with extreme persecution of those questioning the morality or validity of the endless conflicts and divine rule of the Emperor.