Imperium of Man

The Imperium of Man is a fictional galactic empire that contains the vast majority of humanity, set in the Warhammer 40,000 universe created by Games Workshop.

History of the Imperium
The Imperium was founded by the Emperor of Mankind (Master of mankind, ruler of humanity and God of the human race) at the end of the "Age of Strife", a period of anarchy, lawlessness and senseless destruction that lasted for dozens of centuries and during which all but the faintest traces of the vast, advanced galactic civilization built by men in previous eras disappeared.

However, when the warpstorms of the Age of Strife subsided, the Emperor set forth to unite mankind under his rule, turning his hordes of techno-barbaric warriors into the first superhuman Space Marines.

After having secured the scientific posts and spacedocks of Luna, along with the factories and weaponshops based on Mars, the Emperor built a warfleet with which he undertook the Great Crusade, which lasted for two centuries and ended with the formal establishment of Imperial Rule over all but the most scattered and distant human colonized worlds.

During this period, the Emperor employed his most potent soldiers, the Space Marines, and their born leaders, the Primarch. These, coupled with the combined might of the Imperial Army/Navy (later the Imperial Guard and the Imperial Navy as separate organizations), made Mankind the preeminent force to contend with in the galaxy, as its teeming numbers fulfilled what many saw as Man's destiny to rule the galaxy.

Initially the Imperium was a secular absolute monarchy headed by the Emperor. After the Horus Heresy but before the founding of the Ecclesiarchy, the Imperium was able to survive and function well against all its threats as a feudal realm headed by the High Lords of Terra and protected by the Inquisition. Codex: Witch Hunters gives a detailed history of the Imperium, starting with the realm that the Emperor himself created, to the founding of the Ecclesiarchy 3000 years after his death, and the resulting change of the Imperium from a relatively secular institution to a theocracy in which men's rights, freedoms, and even personal happiness became seen as sins, and only suffering and death for the Emperor were now recognized as virtues. Even within the Ecclesiarchy itself, attempts at reform (though only successful in the short term) have been made. Most notable of these was the Age of Apostasy, in which a radical preacher named Sebastian Thor led a revolutionary movement that eventually reached Terra itself and then proceeded to lay siege to the Imperial palace. Several Space Marine Chapters, including the Ultramarines, Dark Angels, and Space Wolves, sided with Sebastian Thor during this revolt. The civil war was finally ended when Goge Vandire, Ecclesiarch and Lord of the Administratum, was turned on and killed by his own bodyguard, the Sisters of Battle. After these events, Sebastian Thor was proclaimed Ecclesiarch, and he attempted to institute a series of reforms to improve the condition of the Imperium's way of life. However, these reforms did not survive long after his eventual death, and the Imperium quickly sank back to its former societal lows, with the Ecclesiarchy again becoming an institution dedicated entirely to the abuse of power against its own followers.

The Imperium in the 41st millennium
The Imperium is nominally ruled by the most beneficent God-Emperor of Mankind. However, since his ascension to the Golden Throne following his confrontation with Warmaster Horus, the duties of actually ruling the Imperium are carried out by the Senatorum Imperialis, the twelve High Lords of Terra. The identities and precise responsibilities of these High Lords vary, but members include a representative of the Inquisition, the Master of the Administratum, the Fabricator General of the Adeptus Mechanicus, and the Lord Commander Militant, supreme commander of the Imperial Guard.

Ultimately, the High Lords are in control of the entire Imperium, and are responsible for maintaining the functioning of the Imperium through the Adeptus Terra and the Imperial Commanders. In practice, given the galactic size of the Imperium, a lot of the outlying regions are left to fend for themselves without any involvement of the central government.

While most of the Imperium is dystopian, the empire is so massive and sprawling that it includes countless different worlds, ranging from neolithic jungles to polluted ecumenopolises (Warhammer 92-3). For example Gudrun, a world mentioned in the Eisenhorn Trilogy by Dan Abnett, is similar to an idyllic 18th century Merry England, with stately manors controlling vast estates of rolling green hills studded with small villages, while Catachan is a hellish Death World filled with carnivorous plants (see Planets of Warhammer 40,000).

The Adeptus Terra
The Adeptus Terra is the enormous priesthood and bureaucracy of Earth, whose scriptoria, continent-sized archives and pilgrimage sites occupy nearly all of the holy hiveworld of Terra that is not taken up by the Sanctum Imperialis, the Emperor's own resting place. The Adeptus Terra is so immense, and operates so slowly, that whole departments of it still service agencies which no longer exist and worlds dead for thousands of years.

The Administratum
One of the more useful divisions of the Adeptus Terra is the Adeptus Administratum. This organisation's main purpose is the assessment of planetary tithes: the goods, war materials and Guard regiments each Imperial world is regularly required to provide for the Imperium. However, it has also acquired many other interplanetary organisational duties.

The Ecclesiarchy
The Adeptus Ministorum, also known as the Ministorum or Ecclesiarchy, is the Church of the God-Emperor. Although the Ministorum allows variations of Imperial faith to flourish, "The only cult we do not abhor is that of the Emperor", and the division between heresy and pious zeal can be hair-thin and malleable to those with power. Most versions of the Imperial faith encourage productivity ("Work is Prayer"), adherence to duty, obedience to authority, thankfulness to the Emperor and other such important virtues.

It is worth noting that the Ecclesiarchy did not exist formally until about 3000 years after the Emperor's incarceration in the Golden Throne. Prior to this it was simply the largest and strongest of the various Emperor-cults in the Imperium, which eventually grew to absorb or destroy competing cults. Once several High Lords of Terra converted and joined this cult, it was only a matter of time before it came recognized, adopted, and eventually declared the state religion of the Imperium.

The Departmento Munitorum
The Departmento Munitorum is the central command of the Imperial warmachine, organising the logistics of planetary tithes, troop movements and troop deployment. The Departmento is far more decentralised than the other divisions of the Adeptus Terra, establishing a presence on any world with a significant tithe-grade. Distress calls from an invaded world are processed by the Munitorum, and will be passed up the ladder of system-subsector-sector-Segmentum-Imperium HQ until a division with enough reach can raise the armies needed from neighbouring systems and respond. Thus, the harder a foe strikes at the Imperium the greater the retribution will be.

The Adeptus Mechanicus

 * See main article: Adeptus Mechanicus

The Adeptus Mechanicus, the Tech-Priests of Mars, are the engineers and technicians of the Imperium, and create most of the Imperium's more advanced machinery and weaponry, build and maintain the Titan Legions and so on. They are in effect a political entity by themselves, containing their own hierarchy of laws and armies.

Prior to the founding of the Imperium, the tech-priests were an independent entity unto themselves, and had already settled various worlds througout the galaxy with seed worlds of their own planned Empire. Their alliance with the Emperor was as much a matter of convinience as of conquest by him.

The Inquisition

 * See main article: Inquisition

Independent of the rest of the Adeptus Terra are the Holy Orders of the Emperor's Inquisition. They are the ultimate judicial and police authority in the Imperium, second only to the Emperor himself.

Officio Assassinorum

 * See main article: Officio Assassinorum

An inconspicuous but vital part of the Imperial machinery of war, the Officio Assassinorum trains and deploys assassins all over the galaxy, to seek out and exterminate dangerous individuals. The deployment of one of their operatives must be sanctioned by the High Lords of Terra. In times of outright war, assassins are typically deployed under the watchful eye and nominal command of an Inquisitor.

The Imperial Commanders
In addition to the Adeptus Terra and the militaries, the High Lords also command the Segmentum Commanders, who each oversee one of the five galactic regions known as the Segmentae Majoris: Segmentum Solar, Segmentum Pacificus, Segmentum Obscurus, Segmentum Tempestus and Ultima Segmentum. Each Segmentum Commander oversees his sector Commanders, who in turn oversee subsector Commanders, who oversee Imperial Commanders, also known as planetary governors. The higher ranks in this system are usually combined with a basic planetary governorship as well as interplanetary duties. This system is the means by which the Imperium, which is largely a confederacy, maintains control of the separate planets that make it up.

An Imperial Commander is the Imperially instituted ruler of a world. However, because of the distances involved and the unstable nature of Warp communication, Commanders generally operate very autonomously. This allows quite a lot of variation in the governments of Imperial worlds. Many governorships are hereditary (examples of this include Segmentum Commanders of Segmentum Tempestus and the royals of Volpone), but it is also possible for a planet to have an elected Commander (such as the Electors of Tanith), a tyrant Commander who rules by force of arms, or anything in between. So long as the Commander fulfills his duties to the Imperium, his rule will generally go unquestioned by central authorities.

A rare few Commanders preside over feral or medieval worlds where the Imperium has not seen fit to introduce modern technology. These Commanders usually remain distant on orbital installations, only occasionally visiting the planet to control mutation and heresy, as well as collect the modest tithes these planets pay.

The Imperial duties of a Commander include paying the planetary tithe to the Administratum, controlling mutation, insurrections and heresy on his world and maintaining a planetary defence force capable of defending the planet in the event of invasion. The Planetary Defence Forces (abbreviated to PDF) should be able to halt attacks from most foes, or at least hold out until reinforcements arrive, which could take a period of months or even years.

A relatively small number of Imperial worlds are not ruled by a Commander, but are overseen by an alternate organisation such as the Adeptus Terra, Imperial Guard or Space Marines. These 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, Esteban VII, Lucius, Ryza, Triplex Phall and Fortis Binary), the Cardinal worlds of the Ecclesiarchy, which are given entirely over to education and worship of the God-Emperor (Ignatius Cardinal, Ophelia VII), fortress worlds of the Imperial Guard (Cadia), and the Space Marine homeworlds (Fenris, Rynn's World, Macragge, Baal, Prometheus, Caliban, Medusa).

Forces of the Imperium
In the Warhammer 40,000 universe, the Imperium represents mankind's only hope for survival in the grim, merciless future of the forty first millennium. The Imperium is surrounded by alien species, and is also under continual attack by the forces of Chaos, and at least one extragalactic species (the Tyranids).

The Imperium's defence forces consist of the: The forces of the Inquisition have absolute authority to combat enemies both within and outside the Imperium. Most inquisitors belong to one of three orders:
 * Imperial Guard
 * Imperial Navy
 * Space Marines
 * The Emperor's bodyguard the Adeptus Custodes, or the Custodian Guard
 * Adeptus Arbites
 * The Ordo Malleus, or Daemonhunters, including the Grey Knights
 * The Ordo Hereticus, or Witch Hunters, including the Sisters of Battle
 * The Ordo Xenos, or Alien Hunters, including the Deathwatch Space Marines.

The psychic blank Sisters of Silence, are present in the Horus Heresy collectible card game.

The Adeptus Mechanicus also contribute to the defense of the Imperium
 * Titan Legions
 * Skitarii

Together, these help defend the Imperium from various enemies, which include:
 * The forces of Chaos
 * The Eldar and Dark Eldar
 * The Tyranid Hive Fleets
 * The various Ork 'Waaagh!'s
 * The Tau Empire
 * The Necrons

Background to the Imperium in other Science Fiction
The Imperium itself, keeping with the dystopian themes of Warhammer 40,000 is a highly oppressive techno-theocracy similar to the Empire of Man found in Frank Herbert's Dune. It also resembles 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. The Space Marines are super-humans with modifications to their physical and mental makeup for combat much like the Armoured Mobile Infantry of Robert A. Heinlein's Starship Troopers, who are highly trained and also recieve hypno-therapy and mental conditioning, and various drug injections to increase their battlefield endurance to superhuman levels). Their unswerving and blind loyalty to their militaristic God Emperor is similar to the Fremen's in Dune. Many Space Marines are raised in harsh environments, much like the Fremen and Sardaukar. Similarities to Dune also exist in the Navis Nobilite, or Navigator Houses, which parallel the Spacing Guild in Frank Herbert's work, as well as in extensive references to the role of powerful nobility and merchant houses in galactic politics.