Timeline of the Warhammer 40,000 Universe

This article briefly summarises the known historical events of the Milky Way Galaxy from human prehistory up to the end of the 41st Millennium in the Warhammer 40,000 setting. Throughout this article, comparative references to present dates will be made with respect to the approximate decade 990.M41 - 999.M41 of the Imperial Calendar. This is the time period in which the perspectives of the Imperium of Mankind and the Eldar are particularly relevant and it represents the present time. All dates are given in the format 999.M41, which should be read as the year 40,999 AD in the Gregorian Calendar.

Birth of the Star Gods
The birth of the entities known as the Star Gods occurred at the same time as the moment of Creation itself, as they formed from the vast, insensate energies first unleashed by that churning mass of cataclysmic force. In that anarchic interweaving of matter and energy, the sea of stars began to swirl into exitence and for an eon the universe was nothing more than hot hydrogen gas and light elemental dust ruled over by the gravitic force of billions of newborn suns. Long before the first planets had formed and cooled, the very first truly self-aware beings emerged, their thoughts encased within the lines of force produced by the plasma and electromagnetic flares of the stars themselves. In later times, these entities would become known as the C'tan, but early in their existence they were nothing like the malevolent beings they would eventually become. They were little more than monstrous energy parasites that suckled upon the solar energies of the stars that had brought them into existence, shortening the lives of otherwise main-sequence stars by millions of standard years. In time, these star vampires learned to move on the diaphanous wings of the universe's electromagnetic flux, leaving their birthplaces to drift through the cosmic ether to new stellar feeding grounds and begin their cycle of stellar destruction once more. Beings of pure energy, they paid no mind to the hunks of solid matter they passed in the vacuum of space, the blazing geothermal fires and weak geomagnetic fields of these nascent planets insufficient to be worth feeding even their ravenous hunger.

The Old Ones
Just as the stars gave birth to their children so the planets of the newborn galaxy eventually gave birth to lifeforms composed of matter which began the long evolutionary climb to self-awareness. The first sentient beings of the Milky Way Galaxy known to have developed a civilisation technologically advanced enough to cross the stars was a reptilian race of beings called the Old Ones by the Eldar, who knew them best. They possessed a slow, cold-blooded, but still deep wisdom, having long studied the stars and raised astronomy and physics to such a level that their science and technology appear to humanity like an arcane art. Their understanding of the workings of the universe were such that they could manipulate alternate dimensions and undertake great works of psychic engineering. Their science allowed them to cross the vast gulfs of space with only a single step through the myriad Warp Gates they built to connect the worlds of the galaxy in a vast network much like the Eldar Webway of today, though on a much larger scale. The Old Ones spread their spawn to many places in the galaxy, but they also knew that all life was precious. Where they passed, they seeded new intelligent species and reshaped thousands of worlds to make them their own according to their predetermined environmental and geographic criteria. It is believed by some in the Adeptus Mechanicus that even Terra felt the Old Ones' touch long before humanity's rise to self-awareness, though this notion is considered heretical at best by the Ecclesiarchy, as the Imperial Creed teaches that Mankind was made in the image of the God-Emperor before his spirit was incarnated in physical flesh millennia ago.

The Old Ones civilization reached its height in excess of 60 million years ago. The Old Ones were responsible for the creation or genetic advancement of most of the currently active intelligent species of the galaxy, including the Eldar, the Krork (the Ork's precursors), the Slann and the Jokaero. The Old Ones were potent psychics who routinely used the powers of the Warp for a wide variety of technological applications. The Old Ones constructed a system of instantaneous faster-than-light portals through Warpspace that were ultimately adapted to create the Eldar's Webway (and was its more advanced precursor). These portals connected all of the Old Ones' colony worlds across vast swathes of interstellar space.

The Necrontyr
As the Old Ones spread across the galaxy, younger, fiercer intelligent races struggled upwards in their wake. The Necrontyr were one such species, born on a world scourged by an unstable star that drove their evolution forward with atomic winds, solar flares and plasma storms. What little information the Imperium has on the Necrontyr tells that their lives were short and uncertain, their bodies blighted and consumed at an early age by the terrible cancers and other illnesses linked to the high levels of ionizing radiation given off by their sun. Necrontyr cities were built in anticipation of their inhabitants' early demise, as the living were only brief residents living in the shadow of the vast sepulchres and tombs of their ancestors. On the Necrontyr homeworld, the greatest monuments were always built for the dead, never the living. Unable to find peace on their own world, the Necrontyr blindly groped outward into the universe to explore other stars. Using stasis crypts and slow-moving, sub-light, antimatter-powered torch-ships that were clad in the living metal known as necrodermis to resist the millennia-long journeys through the void, the Necrontyr began to colonise distant worlds. Sometime during their slow expansion, the Necrontyr encountered the Old Ones. The colonisation of much of the galaxy by the reptilian mystics had been immeasurably swifter and more expansive than that of the Necrontyr because of their Warp Gates and mastery of the Immaterium. That, and the Old Ones' incredibly long, if not downright immortal lifespans, kindled a burning, jealous rage in the Necrontyr, which ate at their culture spiritually as much as their physical cancers consumed their bodies. The Necrontyr were astonished to learn that another intelligent species enjoyed such long lives while their own were cut so brutally short. As their surprise turned to jealousy and then hardened into hatred, the Necrontyr turned their entire civilisation towards destroying the Old Ones and all of their spawn across the galaxy.

The War in Heaven
The terrible wars between the Old Ones and the Necrontyr that followed, known in Eldar myth as the War in Heaven, would fill a library in their own right, but the Necrontyr could never win. Their superior technology was consistently outmanoeuvred by the Old Ones thanks to their mastery of the Webway portals and Warp Gates. The Necrontyr were pushed back until they were little more than an irritation to the Old Ones' dominance of the galaxy, a quiescent threat clinging to their irradiated world among the Halo Stars, exiled and forgotten. The Necrontyr's fury was cooled by their long milllennia of imprisonment on their homeworld, slowly transforming into an utter hatred towards all other forms of intelligent life and an implacable determination to avenge themselves upon their seemingly invincible enemies.

From the earliest days of their civilisation, Necrontyr scientists had been deeply engaged in stellar studies to try to understand and protect themselves from their own sun's baleful energies. After long, bitter centuries of searching for some power to unleash upon the Old Ones, the Necrontyr researchers discovered unusual electrodynamic anomalies in the oldest, dying stars of the galaxy. In the complex skeins of the energetic plasma of these suns, the Necrontyr found a sentience that was more ancient than that of any of the corporeal species in Creation, including the Old Ones, entities of pure energy that had spawned during the birth of the stars eons before. These entities had little conception of what the rest of the universe entailed when the Necrontyr first found them, feeding upon the solar flares and magnetic storms of these bloated red giants. Here was the weapon the Necrontyr had long sought to bring about the downfall of the Old Ones, beings they believed were the progeny of the death-god they worshipped.

The power of these star-born creatures was incredible, the raw energy of the stars made animate, and the Necrontyr called them the C'tan or "Star Gods" in their own tongue. The C'tan were dispersed across areas larger than whole planets, their consciousnesses too vast for humanoids to comprehend. How the Necrontyr ever managed to communicate with them is unknown to the Adeptus Mechanicus. Understanding that such diffuse minds could never perceive the material universe without manifesting themselves in a materal form, the Necrontyr forged physical shells for the C'tan to occupy, cast from the living metal called necrodermis that they had once used for their colony torch-ships. Fragmentary Eldar legends tell of translucent streamers of electromagentic force shifting across space as the star vampires coiled into their new bodies in the physical realm across an incorporeal bridge of starlight.

Incomprehensible forces were compressed into the living metal of the necrodermis bodies which the Necrontyr had forged as the full power of the C'tan at last found form. As the C'tan focused their consciousnesses and became ever more aware of their new mode of existence, they came to appreciate the pleasures available to beings of matter and the other realties of corporeal life. The deliciously focused trickles of electromagnetic energy given off by the phycial bodies of the Necrontyr all about them awakened a new hunger in the C'tan very unlike the one they had once sated using the nourishing but essentially tasteless energies of the stars.

For their part, the Necrontyr soon fell into awe of their discoveries and the C'tan moved to take control over their benefactors. The powers of the C'tan manifested in the physical world were indeed almost god-like and it was not long before the C'tan were being worshipped as the Star Gods the Necrontyr had named them. Perhaps they had been tainted by the material universe they had become a part of, or perhaps this had always been their nature even when they were bound to the suns they fed upon, but the C'tan proved to be as cruel and capricious as the stars from which they had been born. They soon revelled in the worship of the Necrontyr and feasted upon the life energies of countless mortal slaves.

The Rise of the Necrons
Armed with weapons of god-like power and starships that could cross the galaxy in the blink of an eye through the use of quantum phase technology, the Necrontyr stood ready to begin their war against the Old Ones anew. But the C'tan had another gift for their mortal subjects. They offered the Necrontyr a path to immortality and the physical stability their race had always craved. Their diseased flesh would be replaced with the living metal of necrodermis that made up their Star Gods' own physical forms. Their discarded organic husks would be consumed and their cold, metal forms would then be free to pursue their great vengeance against the Old Ones and the rest of a hateful universe, freed forever from the weaknesses of their hated flesh. Whether the Necrontyr actually realised the price they would actually pay for accepting this pact with the C'tan is not known, but their species was utterly purged, their essences fused with the robotic necrodermis bodies their scientists had crafted through the power of the C'tan. The Necrontyr became the Necrons, cursed to the eternal servitude of their Star Gods. The C'tan feasted upon the entire Necrontyr race's life energies even as they made the transfers, leaving behind only the ghostly echoes of the Necrontyr's consciousnesses. Only a few of the most strong-willed Necrontyr retained their intellect and self-awareness and even they were but shadows of their former selves. purged of so much of what had made them unique individuals.

The Necrons cared not at all for their loss; all that mattered to them was that they would live forever without disease or death as their Star Gods had promised. Only one thing truly remained of the old Necrontyr - their burning hatred for all the other living, intelligent species of the universe. Legions of the undying living metal warriors set out into the galaxy in their Tomb Ships and the stars burned in their wake. The Old Ones' mastery of the Warp was now countered by the C'tan's supremacy over the physical universe and the ancient enemies of the Necrons suffered greatly in the interstellar slaughter that followed.

The Necrons Ascendant
The C'tan now dominated the galaxy. The last planetary bastions of the Old Ones were besieged and the intelligent races they had once nurtured became cattle for the obscene hunger of the C'tan. To the younger sentient species of the galaxy, the Necrons and their Star Gods were cruel masters, callously harvesting their populations at will to feed the C'tan's ceaseless hunger. The C'tan were figures of terror who demanded their adoration and fear in equal measure. For unknown reasons, but probably because their individual hungers for mortal life energies knew no bounds, the C'tan ultimately began to fight amongst themselves for both sport and out of spite as they unleashed destructive forces beyond mortal comprehension. Among the Eldar, an ancient myth holds that their Laughing God tricked the C'tan known as the Outsider into turning on its brothers and beginning their long war for ascendancy. In the course of the C'tan's struggle against one another, whole planets were razed, stars were extinguished and whole solar systems were devoured by unleashed black holes. New cities were built by the efforts of millions and then smashed down once more. As the "red harvests" of the C'tan and their Necron servants grew thin, C'tan eventually devoured C'tan, until only a few were left in the universe and they competed amongst themselves for a long age.

Eventually, even the Old Ones, who had once been defined by their patience and unstoppable will, became desperate in the face of the Necron assault. They used their great scientific skills to genetically engineer intelligent beings with an even stronger psychic link to the Warp, hoping to create servants with the capability of channeling psychic power to defend themselves. They nurtured many potential warrior races, among which were believed to be the earliest members of the Eldar species and many other xenos races, including the Rashan, the K'nib and many others. Millennia passed as the Old Ones' creations finally bore fruit and the C'tan and their Necron servants continued to extinguish life across the galaxy.

The Tide Turns
The Old Ones' psychically-empowered servant races spread across the galaxy, battling the advanced Necron technology with the psychic power of their Warp-spawned sorcery. Facing this new onslaught, the C'tan's empire was shattered, as the psychic forces of the Immaterium were anathema to soulless entities whose existence was wholly contained within purely physical paterns of electromagnetic force. For all the destruction they could unleash, they were unable to stop the Old Ones and the younger races' relentless advance across the stars.

The C'tan, unified by this great threat for the first time in millions of years, sought a way to defeat the soul-fuelled energies of the younger species. They initiated a great warding, a plan to forever defeat the psychic sorceries of the Old Ones by sealing off the material universe from the Warp, a plan whose first fruits can still be found on the Imperial Fortress World of Cadia in the form of the great pylons that litter the surface of that world in intricate networks and create the area of space-time stability near the Eye of Terror known as the Cadian Gate. With their god-like powers, it was only a matter of time until the C'tan succeeded and the greatest work of the C'tan was begun. But before it was complete, the seeds of destruction the Old Ones had planted millennia before brought about an unforeseen cataclysm. The growing pains and collecive psychic flaws of the younger races threw the untapped psychically reactive energies of the Immaterium into disorder. War, pain and destruction were mirrored in the bottomless depth of the sea of souls that was the Warp. The maelstroms of souls unleashed into the Immaterium by the carnage of the War in Heaven coalesced in the previously formless energies of the Warp. Older entities that had existed within the Immaterium transformed into terrifying psychic predators, tearing at the souls of vulnerable psykers as their own environment was torn apart and reforged into a realm of Chaos.

The Enslaver Plague
The denizens of the Warp clustered voraciously at the cracks between the Immaterium and the material universe, seeking new ways to enter the physical realm. The Old Ones brought forth new genetically-engineered warrior races to defend their last strongholds, including the technology-mimicking Jokaero and the formidable, green-skinned Krork who were the ancestors of the present day Orks, but it was already too late. The Old Ones' intergalactic Webway network was breached from the Immaterium and lost to them, several of their Warp Gates were destroyed by their own hands to prevent the entities of the Warp from spreading to uncorrupted worlds and Old Ones' greatest works and places of power were overrun by the horrors their own creations had unleashed. The most terrifying of these horrors were the Enslavers, Warp entities whose ability to dominate the minds of the Younger Races and create their own portals into the material realm using transmuted possessed psykers brought them forth in ever greater numbers. For the Old Ones, this was the final disaster as the Enslavers took control of their servants. The Pandora's Box unleashed by the creation of the Younger Races finally scattered the last of the Old Ones and broke their power over the galaxy once and for all. Life had stood at the edge of an apocalypse during the War in Heaven between the Old Ones and the C'tan. Now as the Enslavers breached the Immaterium in epidemic proprtions, the survivors looked doomed.

The C'tan and Necrons Entombed
The Necrons had been vindicated in their pursuit only of science and control over the material realm and certainly took pleasure in seeing the Old Ones' civilisation collapse as a result of their over-indulgence of psychic power. Unfortunately, it seemed that the last of their own masters' food supply would be lost along with it. The C'tan, however, had a solution to even this as a result of their immortal perception of the passage of time. They would allow the Enslavers to take what was left of the sentient life in the galaxy and let it become an interstellar wasteland; the psyker swarm would then die away and in time the galaxy would evolve new lifeforms for the C'tan to consume. It would take millions of years, but what mattered is that they and their Necron servants would be there to take advantage of it.

The C'tan chose to escape the great catastrophe that was coming by descending into Necron stasis-tombs that would be sealed for tens of millions of Terran years. Their machine slaves and Necron warriors would guard them while they slept on Tomb Worlds purged of all life to keep the Enslavers from their door. Only when they were distrubed by a sentient species with the correct physical characteristics that would allow them to be both mastered and consumed as the Necrontyr had been would the Star Gods reemerge into the galaxy. This plan worked with an amazing degree of success until the Necrons were awakened by the forces of the Imperium of Man in the late 41st Millennium to plague the galaxy once more. By that time, only two of the C'tan emerged. They discovered a new and unexpected age of interstellar civilisation and war much like the one they left behind 65 million years ago. The galaxy is blossoming with life once more but is still overrun with latent psykers and worshippers of the infernal Chaotic Warp energies unleashed during the War in Heaven. It will take time and a great many machinations for the C'tan to regain their rightful places as the rulers of the galaxy; the agents of Chaos must be overthrown; the dangerous Eldar, inheritors of the Old Ones' mantle, eliminated; the great work cutting off the material universe from the Warp completed and Mankind subjugated like the Necrontyr before a new age of red harvests can truly begin. But the C'tan and the Necrons are ageless and undying, their technology is still unmatched by any of the Younger Races and time is always on their side...

The Age of Terra and the Stellar Exodus
For millions of standard years after the Necrons and their C'tan masters went into hibernation on their Tomb Worlds, the devastated sentient populations of the galaxy slowly recovered from their "red harvests." In time, the Eldar emerged as the most dominant civilisation in the galaxy, with the core of their star-spanning empire located in the region of what would later become the Eye of Terror Warp rift. But on the planet called Earth and later Terra by its inhabitants, a humanoid species known as Mankind was rising to prominence over 40,000 standard years ago. During the Age of Terra, or the Age of Progress as it is sometimes called by Imperial historians, the human race advanced beyond its ancient pre-industrial past to obtain spacefaring capability and began to slowly settle the habitable worlds in its own solar system and in the star systems near its homeworld using massive sublight starships.

The Stellar Exodus which occurred during the Age of Terra is a poorly-understood period of human history which is generally accepted to cover the majority of Mankind's initial forays into interstellar space and the genesis of most of the oldest human colonies, beginning at some unknown point in the mid-to-late 3rd Millennium. This period is generally understood to lead into the Dark Age of Technology sometime around the 15th Millennium. During much of the Stellar Exodus, humanity lacked any knowledge of the existence of the Warp or Warp drive and so was forced to travel between the stars in great sublight generation ships or using cryogenic hibernation.

Dark Age of Technology
Much of the era of human history known to Imperial historians as the Dark Age of Technology that lasted between approximately the 15th Millennium and the 25th Millennium is mysterious. It was in this time that the psychic mutants called Navigators were first born, and combined with the invention of the Warp-Drive, allowed humanity to travel between worlds faster than the speed of light by using the dangerous hyperdimensional, psychically-reactive medium of the Immaterium or Warp. The existence of rapid interstellar travel allowed human colony worlds to interact on a normal timescale for the first time and interstellar commerce and communication became possible, allowing like-minded human worlds to join into political and economic combines for their mutual benefit. Eventually, at some point during this era, all of humanity was united beneath some form of federated interstellar government. What is also known (largely from the works of Keeper Cripias) is that a group known as the Golden Men relied on the works of the Stone Men in order to create a fantastically prosperous interstellar society, but one devoid (by later Imperial standards) of spirituality or piety, focused instead upon the advancement of science and technology. The Stone Men are known to have created a third group, the Iron Men, postulated to be some form of artificially intelligent robots, in order to assist them in their labors and carry out military duties. The Iron Men became uncontrolled and rebelled against their human creators, and a cataclysmic conflict broke out, resulting in a partial Malthusian Catastrophe across much of the settled galaxy in which there were no longer enough resources to support the vast populations of human beings. Even worse, following the destruction caused by the war against the Iron Men, human psykers began to appear in large numbers across many human colony worlds, one of the harbingers of the final decline of the Eldar empire which controlled even more of the galaxy than mankind did in these years. The result was humanity's first introduction to the daemonic horrors of the Warp and the ultimate collapse of human interstellar civilization during what became known as the Age of Strife.

The Age of Strife
During the so-called "Dark Age of Technology," humanity had reached its scientific and technological peak. The "Standard Template Construct", or STC, a computer database of schematics for all known advanced human technologies, had been perfected by human scientists and engineers and allowed an unprecedented expansion of humanity throughout the galaxy. One of the reasons humanity was so successful at conquering a large part of the galaxy was the development of the artificially-intelligent constructs now only known in Imperial legend as the "Iron Men". These powerful and fully intelligent combat robots won many wars for humanity, but for some reason turned against their masters at the end of the Dark Age of Technology. The war was eventually won by humanity, but at a great cost. The damage was catastrophic and had shattered much of humanity's power. Unfortunately, this was only the beginning of mankind's misfortunes.

As humanity became widely dispersed across the galaxy during the Age of Technology, the ancient Eldar empire began its decline; the great success of the advanced Eldar race had led to decadence and hedonism on a grand scale. Within the immaterial, psychic universe of the Warp, the spiritual corruption of the Eldar civilization was reflected in the forming of a new Chaos God, Slaanesh, which in turn caused massive disturbances in the Warp; parts of the galaxy became isolated by these Warp Storms, making Warp travel and telepathic interstellar communication increasingly impossible as the years passed, cutting off many human colony worlds from one another, including those of the Solar System.

Towards the end of the Age of Technology psykers first appeared among humanity. While persecuted on many backwards, regressive human worlds as witches, in enlightened and progressive societies these psykers were at first protected and accepted. The initial intolerance for psykers would later seem prescient, as many human worlds fell to the dominance of daemons and other Warp creatures using possessed psykers as gateways into the physical world. Only worlds which had rigorously suppressed psykers survived the Age of Strife.

The Age of Strife followed the Age of Technology, as human civilisation collapsed in widespread insanity, daemonic possession, anarchy and inter-human civil war. Terrible weapons of the golden age of technology were unleashed, devastating many human colonies and turning once-verdant worlds such as Baal Secundus into irradiated desert planets. Many isolated and vulnerable human-colonized worlds also became prey to hostile alien races, such as the Orks.

In a relatively short span of time, the once galaxy-spanning human civilization was brought to its knees, and was forced to endure nearly five millennia of anarchy, terror, war, genocide and slavery. Other than tales of great suffering, little information concerning these long years survived this dark time to be known to the men and women of the Imperium.

The Fall of the Eldar
Before the Fall of their potent interstellar empire, the Eldar were a technologically and psychically advanced humanoid species, generally considered the most powerful race in the entire galaxy. Their technology had advanced so far that little or no labor was required by individual Eldar to provide the daily necessities of life, and as a result, at some point around the 24th or 25th Millennium, groups of Eldar began forming pleasure cults dedicated to the pursuit of experiencing everything that life had to offer.

Despite the prediction of the reclusive Eldar Seers that warned of impending doom if the Eldar did not change their hedonistic ways, government within the Eldar empire soon collapsed and the moral degeneration of their homeworlds and various colony worlds continued unimpeded. As the pursuit of ever more extreme experiences reached its height, death reigned in the streets of Eldar cities, hunter and hunted each being part of a twisted ritual of destruction which consumed millions. Some Eldar were able to see that their now-corrupt society was destroying itself, and fled in disgust; these refugees would settle in the distant, rural colonies of their empire, and would later be known as the Exodites.

Upon dying, the soul of all deceased, sentient beings traverse the bounds of the physical realm and go to rest within the Warp. As more and more corrupt Eldar died, their souls began to coalesce into a larger entity within the Warp, a living representation of the corruption that had taken their lives. This growing presence in the Warp caused massive Warp storms to aggregate across the galaxy, eventually making interstellar travel and communications impossible for the colonies of humanity, bringing on the Age of Strife. This collection of corrupt Eldar souls gained sentience sometime in the early 30th Millennium, creating the being known as the Chaos God Slaanesh, the Prince of Pleasure. When Slaanesh came to be, an ethereal explosion occured that spanned the extent of Warpspace within the Milky Way Galaxy, with the epicentre being the Eldar homeworlds. All Eldar caught in the immense psychic blast were instantly killed, their souls consumed by Slaanesh. Most of the remaining Eldar gods who existed within the Warp were destroyed by Slaanesh. Kaela Mensha Khaine, the Eldar god of war, attempted to combat the new Chaos God, but Khaine's form was shattered and exiled to the mortal realm where it came to rest in the Infinity Circuits of the Eldar Craftworlds but could be embodied in the form of animated statues called "Avatars", which rested in the hearts of the various Craftworlds during times of grave peril. The other Eldar gods to survive the Fall were the trickster god Cegorach (also called the Laughing God), who hid himself within the Eldar Webway, and Isha, who was ripped from the jaws of Slaanesh by the Chaos God Nurgle, who now keeps her as a slave.

The Fall utterly destroyed the once vast interstellar Eldar empire, leaving scattered bands of Eldar fighting for survival. Before the Fall, vast spacecraft called Craftworlds were constructed, enabling those wishing to escape the degeneration of the Eldar homeworlds to flee, along with samples of their lost worlds' flora and fauna. When the Fall occurred, the various Craftworlds rode out the ethereal shockwave in the Warp, some being destroyed in the process. The Exodite worlds, far from the epicentre of the terrible catastrophe, were largely untouched by the birth-scream of Slaanesh. In order to prevent the events of the Fall from ever recurring, the Eldar devised the Path system, by which every Eldar would follow a strict, almost fanatical life path pursuing a specific activity, such as crafting or war, for a portion of their long lifespans, before switching to another Path when the previous one grew stale. In this way, the Eldar hoped to control the extreme emotional and psychic sensitivity that had left them open to corruption by Chaos in the first place. However, some corrupted Eldar did survive the birth of Slaanesh by taking refuge within the Webway itself. These sadistic beings became known as the Dark Eldar, and they later preyed on humans and Eldar alike to find souls they coukld devour to keep their own lives from being consumed by Slaanesh.

The Great Crusade
The Great Crusade began as the Age of Strife came to an end for humanity. The Warp storms isolating human worlds had finally disappeared with the borth of Slaanesh and the Fall of the Eldar, and the Emperor of Mankind, who had united Terra under his rule during the Unifications Wars of the Age of Strife, was ready with his genetically-enhanced Space Marines and the Imperial Army to reunite all of humanity. Making a pact with the Priesthood of the Machine God on Mars, the Emperor promised to spare their lives (the Emperor despised their use of bionics and rigid adherence to organized religion as being against everything that he stood for) so long as they aided him in his mission to reunite humanity across the galaxy. The Emperor was a man of science and technology, and so in him many members of the Cult of the Machine saw the coming of the Omnissiah that had been prophecised. The Mechanicum of Mars pledged their support to the creation of a new Imperium of Man, and the symbol of the Imperium changed from the lightning bolt used by the Emperor during the Unifications Wars on Terra to the double-headed eagle known as the Aquila, to symbolise the union of the empires of Earth and Mars. With the forge factories and industrial output of Mars, the Emperor was able to refit his armies, and more importantly, he now had the use of the Mechanicus' Titan Legions, giant robotic war machines with the potential to dominate the battlefield.

At first, the Imperium's expansion into interstellar space was slow, since the Imperial Army was still small, and more importantly the Emperor's 20 Space Marine Legions were inhibited by the absence of their Primarchs, which made the enhancement time for the creation of a new Space Marine much longer. However, this was to end, as on Cthonia, a planet in a star system not far from Terra, the Emperor for the first time was reunited with one of his missing Primarchs, Horus. Having been discovered at an early age, the Emperor took Horus under his wing and taught him all he knew. Horus and the Emperor had a truly unique bond, that of father and son, and many times they saved each others' lives. But after 30 years, the Emperor discovered another of the Space Marine Primarchs, Roboute Guilliman. Although Horus was pleased at the discovery of one of his brothers, he secretly hoped to always be the Emperor's favorite son.

In time, all the Primarchs were found on the worlds they had been sent to by the machinations of the Ruinous Powers of Chaos, and each was placed in command of their respective Space Marine Legions. The Legions as a result were massively expanded with new recruits from their Primarch's adopted homeworlds, and new Space Marines could now be produced within only a single Terran year. But this acceleration produced fundamental defects within the psyche of each Space Marine which was later to prove fatal to many.

After the Imperial campaign on the world of Ullanor concluded upon bringing that planet into "Imperial Compliance," the Emperor claimed it as the greatest victory of the Imperium to date, and that Horus should be given all credit. Hailing Horus and his Luna Wolves Legion (later renamed the Sons of Horus), the Emperor stated that he would have to leave the expeditionary fleets behind and return to Terra to begin the next, secret phase of his plan to ensure humanity's domination of the galaxy, and that in his place Horus would be declared Warmaster, the de facto commander of all the Emperor's armies on the Great Crusade. Although Horus was troubled that the Emperor should leave him and his brother Primarchs to carry on alone for some unknown reason, with Horus as their new commander, the Imperium's armies and Space Marines continued to expand ever outwards, rediscovering lost human worlds and bringing them into the enlightened Imperium's fold. This situation lasted until the outbreak of the terrible Horus Heresy.

The Horus Heresy
Eventually, the Imperial Warmaster Horus fell to the temptations of the Ruinous Powers of Chaos and attempted to destroy the Imperium from within by usurping the power of the Emperor. The treason of Horus, known in later centuries as the Horus Heresy, spread to embrace approximately half of the Imperium's military forces, from small planetary defence forces, right up to nine Space Marine Legions and several of the Adeptus Mechanicus' potent Titan Legions. The terrible civil war culminated in a massive seige of the Imperial Palace on Terra. After 55 days of fighting, the war was ended by the Emperor and Horus dueling in single combat aboard Horus' flagship in orbit of Terra. Although mortally wounded, the Emperor was able to strike down Horus. The Chaos Space Marine Legions and their allies retreated to the Eye of Terror, and the crippled body of the Emperor was installed into the 'Golden Throne'.

The Age of the Imperium
The Age of the Imperium is the time period that began with the end of the Horus Heresy in the early 31st Millennium, and is typically referred to in the present tense. The approximate time period begins in the 31st Millennium, and continues forward, with the last year represented in Imperial records being 999.M41. The Age of the Imperium is generally conveyed as spanning from the end of the Horus Heresy to the narrative present - a space of approximately ten thousand Terran years.

Age of Rebirth (M31-M32)
During the Age of Rebirth the Imperium of Man slowly recovered from the Horus Heresy. The myriad wars of the Great Scouring were fought in the decades immediately after the end of the Horus Heresy and the death of the Warmaster. In a lengthy campaign, the Imperium's forces hunted and banished the remaining Traitor Marine Legions from human space. Eventually the Chaos Space Marines and the Ruinous Powers' other followers among the Forces of Chaos found refuge in the massive Warp rift known as the Eye of Terror. For a time the Imperium knew peace from the corrupted followers of the Chaos Gods. At the same time, many alien races that had been fought during the Great Crusade reappeared in human space to take advantage of the disruptions caused by the Horus Heresy and plagued the vulnerable worlds of Man. In order to prevent a single person from controlling as much military power as Horus had mastered and eliminate the risk of another large-scale civil war, numerous reforms were enacted to reshape the Imperium's political and military structure. The Imperial Army was divided into the land-based forces of the Imperial Guard, and the space-based forces of the Imperial Navy, each with a separate chain-of-command structure and bureaucracy. The remaining nine Loyalist Space Marine Legions adopted the Codex Astartes written by the Ultramarines' Primarch Roboute Guilliman and were split into the many smaller Space Marine Chapters of the Second Founding that were comprised of only 1,000 men each along with their own supporting spacecraft and planetary fiefdoms.

The byzantine politics of the Imperium took a calamitous turn in 546.M32 when the High Lords of Terra, the successors of the Council of Terra that had been established to administer the day-to-days affairs of the Imperium and now ruled in the Emperor's name were slain to a man on the orders of Drakan Vangorich, the Grand Master of the Officio Assassinorum. A Space Marine retribution force drawn from the Halo Brethren, Imperial Fists and Sable Swords Chapters tracked the Grand Master to an Assassinourm temple. The commander of the Astartes strike force was assassinated as soon as he made planetfall, but the remaining Battle-Brothers carried out the attack without him. Inside the temple they were attacked by 100 Eversor Assassins. Only a single Space Marine survived to reach the Grand Master and end his life with a boltgun. The Imperium descended into anarchy for several years as new High Lords rose to power.

The Forging (M32-M35)
The Forging is also sometimes known to Imperial historians as the Golden Age of the Imperium. During this period the Adeptus Terra brought the most important human-settled star systems of the galaxy that had not been reached by the Great Crusade under Imperial control and expanded the interstellar borders of the Imperium. Internal stability was gained with the establishment of Astropath Choirs on countless worlds, which allowed a reliable network of interstellar superluminal communication to function using the power of an Astropath's telepathy to send and receive mesages across light years. This period also saw the slowing of the decline in the Imperium's technology and the growth of the interstellar economy due to the rediscovery of a valuable Standard Template Construct (STC) database from the Dark Age of Technology in the Cana System as the Imperium expanded. Once more the Imperium repelled the forces of Chaos renegades, heretics and aliens alike across the galaxy and reclaimed countless lost and rebellious regions for the human race.

In 265.M33 Admiral Usurs of the Imperial Navy was cast down by the High Lords of Terra for becoming too ambitious. However, he is still too powerful within the Navy to be executed without intiating a costly civil war, so he is instead dispatched on an Explorator mission to the intergalactic gulf beyond the Milky Way. For the following decade, Usurs' reports reach Terra by Astropath, detailing the conquest of new star systems for the Emperor. After two decades, these reports finally cease. Contact is never reestablished with the star systems Usurs mentioned in his reports.

In 401.M34 the terrible event known as the Howling unfolded. Black Templar Space Marines ended the Catelexis Heresy by executing the Cacodominus, an alien cybernetic psyker whose formidable powers allowed it to psychically control the populace of thirteen hundred star systems! Unfortunately, the Cacodominus' death scream was amplified by the Warp and burned out the minds of a billion human Astropaths as well as distorting the beacon of the Astronomicon. Millions of starships were lost in the resulting upheaval and entire sub-sectors of the Imperium slid into barbarism without the dictats of the Administratum to guide them.

The Nova Terra Interregnum (M35)
The Nova Terra Interregnum is also known as the Time of the Twin Empires and it lasted for 900 standard years during the 35th Millennium. During this period the rebellious Ur-Council of Nova Terra dismissed the authority of the High Lords of Terra and claimed separate rule over the Imperium's Segmentum Pacificus. After almost a millennium of low-grade civil war and political maneuvering, the Cataclysm of Souls in 975.M35 reunited the Imperium. In that year the Ecclesiarchy tried to transform the Imperium into a theocracy and usurp the power of the rest of the High Lords of Terra. Their efforts ended only in stirring up massive religious civil wars against the Ur-Council who were denounced as heretics who stood in defiance of the will of the God-Emperor when they rejected the Ecclesiarchy's attempts to increase its power over the state. This religious rebellion on many worlds of the Segmentum Pacificus ultimately overthrew the Ur-Council and restored the rule of the High Lords over the entirety of the Imperium's territory, though the power of the Ecclesiarchy had been increased throughout the Imperium as a result.

Age of Apostasy (M36)
The Age of Apostasy is another era of Imperial civil war and is considered to be one of the bloodiest eras of the Imperium's history after the Horus Heresy. The Age of Apostasy is marked by the Reign of Blood, when the insane tyrant, High Lord Goge Vandire, became both Ecclesiarch of the Adeptus Ministorum and High Lord of the Adeptus Administratum through bribery, blackmail, coercion and murder. Vandire started an period of time known as the Reign of Blood where multiple wars of faith were fought as Vandire attempted to gain control of the Imperium. The Reign of Blood lasted for 70 years before a messenger delivered the news that heralded its end. On the world of Dimmamar, a man named Sebastian Thor and his sect, the Confederation of Light, denounced Hgh Lord Vandire as a traitor to the Emperor. As an accomplished orator, Thor was able to sway billions to his cause. Eventually Vandire was besieged on Terra by several Space Marine Chapters, and several Imperial Guard Regiments. The Space Marines' fleet unleashed a massive orbital bombardment which caught most of the traitors in the open. Lord Vandire was killed by his bodyguards, the Brides of the Emperor, who were convinced that they had been tricked into betraying the Emperor by Vandire. In the aftermath, the Ecclesiarchy was reformed, and the Brides of the Emperor were reformed into the Adeptus Sororitas, the Sisters of Battle, the armed forces of the Ecclesiarchy and the Chamber Militant of the Inquisition's new Ordo Hereticus. The Ordo Hereticus was intended to root out the internal enemies of the Imperium and prevent the emergence of another Goge Vandire who sought to serve his own selfish ends rather than the will of the Emperor.

The event known as the Plague of Unbelief is also considered part of the Age of Apostasy of the 36th Millennium, although it occurred several decades after High Lord Goge Vandire's death and Sebastian Thor's ascension to the position of Ecclesiarch. Many false prophets appeared throughout the anarchic Age of Apostasy, some little more than madmen leading rebel armies, others spiritual demagogues who commanded worlds and armies. The most powerful of these was the Apostate Cardinal of Gathalamor, Bucharis, whose heresies reached such proportions they became known as the Plague of Unbelief, not to be confused with the Curse of Unbelief, a potent arcane disease spread by servants of the Chaos God Nurgle in the 41st Millennium and better known as the Zombie Plague.

Age of Redemption (M37)
The Age of Redemption marked the era when the Imperium recovered from the sins of apostasy in a rain of blood and tears. The Imperial Cult grew in zeal as never before. Heretic pyres burned night and day on a thousand Imperial worlds as the people of the Imperium sought to mortify their sins against the God-Emperor through the scourging of the flesh of others. Crusade after crusade was launched by the Space Marines and other Imperial military forces to recapture the lost wealth of the Imperium and push back the hordes of Chaos, Orks and other alien threats to humanity. This religious fervour eventually peaked in an orgy of fanatical devotion to crusading in the Emperor's name and thousands of worlds were left with inadequate defenses as sector fleets of the Imperial Navy, Space Marine Chapters and Imperial Guard Regiments are drawn into longer and more terrible Redemption Crusades spurred on by this religious fanaticism.

Among the most devastating of these conflicts were the Abyssal Crusade and the Occlusiad. The Abyssal Crusade of 321.M37 began when Saint Basilius found thirty Space Marine Chapters wanting in their devotion to the Emperor. The guilty embarked upon a crusade into the Eye of Terror to earn their salvation and purge those human-settled worlds stolen from Mankind by the birth of the Dark Prince of Pleasure, Slaanesh. The Occlusiad of 555.M37 started when the northwestern fringe of the galaxy was ravaged by the heretics known as the Apostles of the Blind King, rogue Tech-priests who viewed humanity as an utter affront to the Machine God. The Apostles had uncovered wondrous artefacts from the Dark Age of Technology that made possible the transformation of ordinary stars into supernovae. The constellations of the galaxy were changed forever when the Apostles purged the outer Segmentum Obscurus of human life using these weapons. War raged for a decade until the Navigator Joyre Macran discovered the palace-warship of the Blind King hidden in a fold of the Warp. Escaping with this crucial intelligence, Macran guided the Imperial Navy's Emperor-class battleship Dominus Astra to the palace's location. The Blind King was killed and the genocide ended when the Dominus Astra's lance batteries pierced the palace-warship's hull and without his leadership the Apostles were swiftly overcome and their weapons hidden away in the vaults of Mars.

Emergence of the Tau Empire (M37-M41)
In the late 37th Millennium the humanoid Tau race, located on the arid world of T'au in the Ultima Segmentum, was united under the collectivist ideology of the Greater Good and underwent rapid technological development and a large expansion outwards into interstellar space where they established a new interstellar empire and settled many worlds in the Eastern Fringes of the Milky Way Galaxy. The Imperium of Man only came into contact with the Tau Empire in 963.M41 when the Ultramarines clashed with a Tau expeditionary fleet for control of the cursed planet of Malbede. As a result of this late first contact, the number of conflicts between the Imperium and the Tau have been minimal compared to the wars fought between Mankind and the other, more numerous and widespread interstellar alien species like the Orks and the Eldar. The expansion of the Tau Empire also caused several other intelligent alien species to be incorporated into its ranks, such as the Kroot and the Vespid.

The Waning (M38-750.M41)
With the Imperium's military forces in every branch utterly exhausted by the Redemption Crusades, star system after star system fell to Ork invasion, Chaos insurgence or sheer rebellion. Anarchy throughout many sectors of the Imperium was rife during a dark period in Imperial history that is now called the Waning. Ever more star systems are turned over by the Administratum to direct rule by Space Marine Chapters to preserve stability as only the Astartes possess the inviolable military strength required to restore Imperial control in the more lawless regions of the galaxy.

This period sees the Macharian Conquests (also called the Macharian Crusade) of 392-399.M41 during which Lord Commander Solar Macharius, master of the Segmentum Solar, mustered the greatest human army the galaxy had seen since the Great Crusade. In only five standard years, Macharius reconquered a thousand worlds on the western reaches of the Imperium and his glory carried him into the darkest sectors, places where the Emperor's light had never been known. Upon his death, the whole Imperium wept for the lost commander, but Macharius' conquered territories soon collapse into rivalry and civil war. The Macharian Heresy, as this time is now known, lasted for 70 standard years and stability was only returned to Macharius' conquests through the combined efforts of 100 Space Marine Chapters.

A Black Crusade is the term used to describe a number of mass incursions by Chaos Space Marines and the other Forces of Chaos into Imperial space from the Eye of Terror. The most prominent of these are the Black Crusades led by the Black Legion's Warmaster and Horus' successor as the greatest Champion of Chaos Undivided, Abaddon the Despoiler. The 12th Black Crusade, or Gothic War, was a vast campaign launched by the Chaos Space Marine Warmaster Abaddon of the Black Legion that engulfed the Gothic Sector of the Segmentum Obscurus after that sector was cut off from Imperial reinforcements and communications by a series of massive Warp Storms produced by the will of the Ruinous Powers. It consisted of hundreds of planetary invasions and naval battles spanning the time period 139.M41 - 160.M41 and only ended when Abaddon and his Chaos Space Marines were forced to retreat into the Immaterium with the arrival of Imperial reinforcements as the Warp Storms that had provided cover for their invasion finally dissipated just as mysteriously as they had begun. It saw the destruction of several planets and four of the six irreplaceable ancient alien artefacts known as the Blackstone Fortresses as well as the deaths of millions, if not billions, of Imperial citizens. The conflict was fought almost entirely around the Gothic Sector of Imperial space in the Segmentum Obscurus near the Eye of Terror. Most significantly, the events of the Gothic War revealed the true nature and purpose of the ancient spaceborne alien artefacts known to the Imperium as the Blackstone Fortresses, which had been created by the Old Ones to be used against the Necrons and were capable of destabilising stars and destroying entire solar systems. Most importantly, Abaddon and the Forces of Chaos were able to escape back into the Eye of Terror with one of the Blackstone Fortresses, which was then possessed by a splinter of the mind of the Chaos God Slaanesh.

The Necrons Awaken (M41)
In the late 41st Millenium the dormant Necrons have finally awoken from their long sleep to harvest the sentient races of the galaxy for their masters, the C'tan, once more. In many cases their Tomb Worlds had been resettled by the unsuspecting humans of the Imperium, leading to horrific scenes of devastation as the newly awakened Necrons cleansed whole planets of their populations of fragile human souls. The reason for the Necrons' awakening from their long sleep in the late 41st Millennium is debated amongst the Magi of the Adeptus Mechanicus. Possible catalysts include the Tyranid Hive Mind's Shadow in the Warp or an Adeptus Mechanicus Explorator fleet that disturbed one of their Tomb Worlds, though the first recorded contact between the Imperium and the Necrons came in 963.M41 during the confict between the Ultramarines Chapter and the Tau over control of what turned out to be the Tomb World of Malbede. In that instance, the Ultramarines' Chapter Master Marneus Calgar ordered the use of an Exterminatus against Malbede after allowing the Tau forces to get off-planet to eliminate the much greater Necron threat, but Necrons soon began awakening on their Tomb Worlds all across the galaxy after this event. Regardless of the reason for their awakening, the Necrons proceeded to reap havoc amongst all the peoples of the galaxy.

The Tyrannic Wars (745.M41 - 999.M41)
The Tyrannic Wars are the collective conflicts ignited by the Tyranid race's sudden incursion into the Milky Way Galaxy, beginning in 745.M41 by the Imperial Calendar.

Hive Fleet Behemoth (745.M41)
The first recorded encounter with the Tyranids occurred in the Eastern Fringe of the Galaxy and was documented in reports from the planet Tyran. An Adeptus Mechanicus Explorator station at Tyran identified a collection of worlds in the area that had been stripped bare of their biomass and atmosphere. The station was subsequently attacked and consumed. A year later, an Imperial Inquisitor named Kryptman, who received information regarding the attack, arrived on Tyran to investigate. After searching the planet he chanced upon a data codex hidden deep within Tyran's crust, which contained information about the invaders. The information collected by the Explorators on Tyran allowed Kryptman to identify the pattern of attacks and predict the course of the hive fleet. However, these predictions came too late: several more civilisations were wiped out, largely because astropaths could not send psychic requests for help because of a phenomenon known as the "Shadow of the Warp" - somehow, the presence of a Tyranid Hive Fleet near a planet stops psychic communication and transportation through the Warp, which is the primary method of interstellar communication and transport used by the Imperium's astropaths and Warp-Drive-equipped starships.

The Tyranid force, dubbed Hive Fleet Behemoth in a rare moment of literary imagination at Imperial Command, cut a swathe through the Ultramar Sector, the realm of the Ultramarines Chapter of the Adeptus Astartes. Undeterred by the Space Marines' Chapter fleet, Behemoth reduced Prandium, the Garden World once known as the "Jewel of Ultramar," to bare rock.

Eventually, Chapter Master Marneus Calgar mustered his entire force for a last-ditch defense of the Ultramarines' homeworld of Macragge. Here, during the Battle of Macragge, the hive fleet was completely destroyed. However, the Ultramarines suffered heavy losses, losing their entire Veteran 1st Company in a last stand at the northern polar fortress.

Hive Fleet Kraken (993.M41)
The second wave of Tyranids to fight against the Imperium was known as Hive Fleet Kraken. Instead of throwing one mass of troops against the human armies, this swarm split into countless smaller fleets, each one enveloping whole systems before reinforcements could arrive. Kraken was finally brought to battle on a grand scale at Ichar IV, an Imperial Hive World, in 993.M41. The brunt of this attack was borne by the Scythes of the Emperor and Lamenters chapters of the Space Marines and the Eldar Craftworld Iyanden, all of whom suffered very heavy losses. According to Lieutenant Kage of the Last Chancers Penal Regiment, the Imperial Guard "lost over a million men at Ichar IV", though this may serve simply to illustrate in a very broad sense the scale of the combat against the Kraken, as numerically speaking a million soldiers is not a great burden for an entire Hive World to expend in its defence since it is home to billions of people. The Kraken was not fully destroyed though, and split into several splinter fleets which have continued to represent major threats to the Imperium as they spread and grow like a xenos cancer upon the galaxy. There was little respite for the Imperium after Kraken's near destruction as a new hive fleet emerged soon after.

Hive Fleet Leviathan (997.M41)
The third wave of Tyranid attacks, Hive Fleet Leviathan, appeared from below the galactic plane and attacked from two points in 997.M41, cutting off large portions of the galaxy from Imperial reinforcements. In order to buy some time, the Imperium, under the command of Inquisitor Kryptman, attempted to redirect the attacks of this fleet towards the Ork-held worlds of the Octavius System. While the plan was a success, the Tyranids have since been steadily working their way through Ork space, suffering massive losses, assimilating everything that stands before them. The Imperium has bought itself a century at least to prepare for the next attack, but there is no telling how the Tyranids may evolve thanks to the newly-harvested Orkoid DNA.

Hive Fleet Leviathan also attacked around the same time as Hive Fleet Kraken, making both fleets difficult to deal with for the Imperium as the elements of one or the other would provoke some sort of uprising provoked by Genestealer Cults or invade Imperial worlds outright in the Great Devourer's eternal quest for more biomass to enhance its Hive Fleets' reproduction rates. To date, Behemoth is the only Tyranid Hive Fleet that did not divide its mass into different "tendrils" that attacked Imperial space from several different locations at once, and it suffered the consequences of being less strategically-minded than its successors.

13th Black Crusade (999.M41)
The 13th Black Crusade is the most recent and the greatest of the incursions launched against the Imperium by Abbadon the Despoiler, and was the greatest conflict fought between the Forces of Chaos and the Imperium of Man since the Horus Heresy. Every major faction of the Milky Way Galaxy race fought on one side or the other during this Black Crusade, including the Tau, who used the re-deployment of Imperial forces to the Segmentum Obscurus initiate the Third Sphere Expansion of their empire in the Eastern Fringes of the galaxy, unleashing what became known in Imperial records as the Zeist Campaign. The war led to massive casualties amongst the Imperium and the xenos forces like the Eldar engaged against the Chaotic tides. Among the greatest losses was the presumed death of the greatest of the Eldar Farseers, Eldrad Ulthran, who sacrificed himself in an attempt to recover a Blackstone Fortress that had been used to devastating effect in the space battles surrounding the world of Cadia, the capture of which was the ultimate goal of the Forces of Chaos since it would allow them to create a forward base for a new drive upon Terra to topple the Emperor from the Golden Throne. In the end, the Forces of Chaos were forced into a stalemate with the Imperial forces on the surface of Cadia as the Imperial Navy's combined Battlefleets Obscuras, Solar, Gothic and Pacificus retook control of the Cadian Gate and the orbital space above Cadia, trapping the Chaotic troops on the surface of the Fortress World. But should the Imperial Navy be dislodged from its perch, then Abaddon and the minions of the Ruinous Powers will have a clear path to sweep across the galaxy and dislodge the hated Corpse Emperor from his rule over Mankind. And on Terra, the Adeptus Mechanicus secretly reports to the High Lords of Terra in this same year that the mechanisms of the Golden Throne are failing and they do not possess the knowledge required to repair its ancient technology. Unless a miracle intervenes, the Emperor's body will die and the Imperium and all Mankind will be plunged into the waiting darkness...