Warhammer 40k Timeline: Why is 40th millennium eponymous?

I decided to prepare a simplified timeline to allow you, recruits, to find your way in the glory of the God-Emperor and humanity. The main narrative revolves around our race, which is why this timeline has been prepared from its perspective. Of course, there are also other, much older races – but their time will also come... like all of of humanity's enemies.

Warhammer 40,000, as the name suggests, is set in the 40th millennium, which means it is immensely detached from our times. This allowed the developers of the universe complete freedom in creating various stories and inventing the potential future of our civilization.

So let's move on to the timeline itself, focusing solely on us, humans. The letter "M" stands for millennium, and the numerical value indicates the exact period in question. I'm only mentioning the most important events, because there are a whole lot of side stories.

Chronicle of the Human Empire

M1-M15: The Terra Era

Humanity developed as we know it today – states and nations were created and technologies advanced. From the perspective of 40k, this is a very distant period about which the people of the Empire themselves know very little. All chronicles and sources have been lost in the mists of history. M3 is a crucial time when humanity begins the exploration and colonization of outer space. This era was named the Terra Era.

The process of conquering successive planets was neither efficient nor fast – humans were still far from proper interstellar travel. Huge colonial ships were used, gliding through space, where the colonists were either hibernated or entire generations lived and died aboard, waiting for the opportunity to settle on a suitable planet. Earth, aka Terra, still remained the capital of humanity.

M15-M25: Golden Age of Technology

Humanity reached the peak of technological development at that time, creating inventions far suring the capabilities that the Empire will achieve later on. This period was called the Golden Era of Technology. At that time, people learned to harness the energy of the Warp – a dimension where emotions and souls of sentient beings end up after death – and became aware of the existence of supernatural beings inhabiting this sphere.

This is when the first psionics appeared – they were mutated humans capable of harnessing the energy of the Warp for various purposes. Their abilities were often considered magic, which made them viciously persecuted. The key role in the rapid development of humanity was played by Standard Template Construct (STCs), enabling the production of even the most advanced objects without the need for specialized technical knowledge.

During this period, the Men of Iron were also created – these were advanced, autonomous machines equipped with artificial intelligence, which took over many production and military functions. Humanity was powerful, wealthy, and colonized hundreds of worlds. Unfortunately, a conflict erupted between the Men of Iron and their creators. A devastating war began, which was ultimately won by humans, but the huge losses resulted in thousands of planets getting isolated. And so was the dominance of humanity over the galaxy interrupted.

M25-30: Age of Chaos

Through the activities of the Eldar race and their moral corruption, the Warp was seriously disrupted, making safe travel through this dimension impossible. Human colonies, cut off from galactic transport and with other worlds, have plunged into isolationism.

On the isolated planets, unique cultures, languages, and cults developed, and each of the colonies began to govern by its own laws. Ancient tales of interstellar travels have become legends, myths, and fables spun around campfires. Humanity, as a race, began to regress, and development ceased to paramount – survival became the next big thing.

M30: The Emperor's Revelation and the Great Crusade

The Emperor reveals himself after thousands of years spent on a planet and unites Earth under the sign of his newly emerging Empire. Simultaneously, in his secret laboratories, he creates twenty Primarchs from his own DNA, so that each of them contains a part of his genius, power, charisma, and personality. They are supposed to become the foundation of future Adeptus Astartes orders, i.e. elite, genetically modified human warriors.

Unfortunately, the Primarchs are kidnapped by forces of Chaos and scattered throughout the galaxy. The Emperor, however, does not lose sight of his goal and continues the brutal unification of humanity within the Empire. The new vision involves establishing a completely secular state, in which any manifestation of religion or occultism is ruthlessly suppressed in the name of the new Imperial Truth.

The Father of Humanity, after subjugating the Earth and the entire Solar System, moves further into the stars, conquering more planets into the emerging Empire. During the Great Crusade, he finds his lost sons, who take command of the legions of Space Marines, to bring the Imperial Truth to the entire galaxy shoulder to shoulder with their Father.

M31: Horus Heresy

Here's the single, most important event in the history of the Human Empire, bringing with it huge consequences and changing the entire image of Warhammer 40,000 universe. In these dark times, the Son betrays the Father – the primarch Horus, most beloved by the Emperor and endowed with the greatest power, is corrupted by Chaos and begins a crusade against his Father.

Some of the Primarchs the arch-traitor, bolstering the ranks of his army. Space Marines split into loyalists, who fight for the Empire, and traitors, who are devoted to Chaos. This leads to a galactic-size slaughter and destruction on an immense scale, as the brothers start fighting and killing each other in enormous space battles.

The siege of Terra ends with the death of Horus and the severe wounding of the Emperor, who is placed on the Golden Throne. The Imperator himself is neither alive nor dead, but nevertheless endures on his throne, shielding humanity from threats emanating from the Warp.

As a result of these events, the Empire is heading towards religious fanaticism, many worlds are lost, as are vast amounts of resources, technology, and military potential. The betrayal of Horus tarnishes the entire galaxy, leading to the emergence of heretical Chaos Marines and a direct conflict with the Chaos Gods themselves – humanity stands against an enemy that cannot be defeated by conventional methods.

M32: The Reformation Era

The establishment of the Adeptus Ministorum (Church of the Emperor) leads to a profound reorganization of the Human Empire. In the new faith, the Emperor is elevated to the role of a deity, a guardian of humanity, who protects it from the temptations of Chaos and threats from other races.

The bureaucratic state machine begins to grow exponentially – new institutions and expanded power structures are created. These changes aim to protect the Empire from another heresy. The Empire is transforming into a mega religious cult, seeing fanaticism as one of the few effective methods of protection against Chaos.

Roboute Guilliman, one of the primarchs who survived the Horus Heresy, compiles the Codex Astartes – a document that divides the existing legions of Space Marines into smaller, numerically limited orders. Thanks to this, in case of betrayal, none of them will be able to threaten the Empire on their own.

The era of slow reconstruction begins – the Human Empire, although macerated, tries to regain its former power.

M33-37: The Age of Apostasy and Vandire's Madness

The transformation of the Empire into a religious state led Ecclesia to harbor enormous amounts of influence. The cardinals hence got a strong grip on the political and economic decision making. This caused the Adeptus Mechanicus, Adeptus Astartes, or Adeptus istratum to become opposition to Ecclesiarchy, leading a cold war with it. However, the conflict did not produce a winner, forever stuck in a back-and-forth between the parties. This initiated a great crisis, a collapse of the economy, and total anarchy in the Empire followed.

After years of conflict between religious leaders and bureaucrats, Goge Vandire used his political influence to both become the Master of the istratum (the secular authority) and assume the title of Ecclesiarch (religious authority). He was the first person in centuries to concentrate the power over virtually every aspect of the Empire in his hands. The thing is, Vandire turned out to be a paranoid megalomaniac who saw conspiracies against his life everywhere. He was also a sadist, often hurting innocent citizens of the Empire, claiming that he "purifies their soul in the name of the Emperor." The Reign of Blood has begun.

Vandire's iron fist ruled for nearly 70 years, inducing terror on an unimaginable scale. It was only the Confederation of Light, led by Sebastian Thor, that led to his demise. The war efforts also led to the creation of the Sisters of Battle – an organization of holy brides of the God Emperor, devoted to his cause.

37-40M: Redemption and Waning

The religious zest in the Empire reached its peak – citizens were fully devoted to the faith in the God-Emperor, praying fervently and seeking out heretics, desperate to redeem the sins of the past era. In this spirit, the Crusade of Redemption was created. Its aim was to reclaim the planets lost during recent conflicts. However, despite initial enthusiasm, the Empire quickly began to lose resources and people due to poorly executed expeditions.

The time known as the Era of Decay has come – heretics, mutants, and aliens flooded through the territories of the Empire, sowing chaos and destruction wherever they appeared. In a desperate attempt to maintain control, the Imperial authorities handed over some sectors to the strict rule of Space Marine orders, convinced only they were capable of stopping the impending darkness.

41st millennium – Time of Ending

This is one of the most tumultuous periods in the universe – which isn't surprising since it's the eponymous millennium of Warhammer. Thus, I will highlight significant military campaigns and events that are mirrored in miniature and video games.

M41: The Badab War

The conflict between the loyal Adeptus Astartes in the region of the Chaos Vortex was a bloody civil war and the first such large-scale clash between the Marines since the times of the Horus Heresy. The spark that set the conflict alight was the growing military and political power of the Master of the Order of Astral Claws, Lugft Huron, who ultimately declared the secession of the territories he controlled.

To hide the truth about this conflict, an Edict of Purification was executed – all information about the war was removed or the "official" history was modified in a way that totally obscured the events.

M41: Third War for Armageddon

The planet Armageddon is a key industrial location for the Empire, as the local city-mounds produce hundreds of millions of tons of weapons and equipment. Due to its strategic importance, as many as three wars were fought over it – the first one with the servants of Chaos, and the next two with the green-skinned orcs led by Ghazghkull, the arch-warlord, who poses a threat to the entire galaxy.

The most crucial was the third invasion, which almost destroyed the entire planet. The Steel Legions of Armageddon, led by Commissar Yarrick, finally repelled the hordes of Xenos, and although the war was officially over, numerous battles with the orcs, who did not leave the sector, are still ongoing on the planet. 

M41: Tyranid Invasion – Hive Behemoth, Kraken, Leviathan

The emergence of a new, deadly threat from beyond the galaxy – the Tyranids. This is a race of biological invaders, whose sole purpose is to devour all biological matter. For the first time, the Empire and other races face an enemy who has no ideology, goals, nor fear – it only wants to eat, grow, and evolve. Individual swarms lead to destruction on an unimaginable scale, and the fight against them is extremely exhausting and sometimes even impossible to win. Every race can become their victim.

Two questions appear in the heads of leaders: if such horrors live beyond the known galaxy, what else could be there? And maybe the Tyranids were fleeing from another threat, and if these creatures could be afraid of something... what's scarier than horror itself?

M42: Opening of the Great Rift - Cicatrix Maledictum

A great rift in reality appears in the galaxy, and becomes called Cicatrix Maledictum. It causes the territories of the Empire to be divided in half, creating the Sanctus Empire and the Nihilus Empire. The Emperor's lost son, Roboute Guilliman, returns to his Father's domain, and with him appear the Primaris Marines – enhanced Space Marines, able to turn the tide of victory in many battles.

For the first time in centuries, the Empire has its own champion – the Primarch himself, who miraculously appeared in the darkest hour. Now humanity is trying to unite the separated planets to resist the dozens of enemies attacking it from all sides.

Current WH40k moment – Era Indomitus

Currently, the Empire has been torn apart and is also fighting with Chaos, Tyranids, Necrons, Orks, Tau and... its own self. Guilliman becomes the regent of the Empire and tries to save his Father's civilization, but it is a daunting task – he must reorganize the entire state structure and fight conspiracies behind his back. Unusual alliances with Xenos are being formed, because all intelligent races are aware of what's happening out in the galaxy. The millennium is filled with the drums of war on an unprecedented scale... Indeed, the Emperor's son has organized the successful Indomitus Crusade, but is it enough for the Empire to regain its strength and still persist?

After finishing this sentence, the elderly man straightened up from the keyboard of his cogitator. "Hmmm, this will be good," he muttered under the breath, slowly rising from the chair. He grabbed the cane and headed towards the nearest viewport, looking into the emptiness of space. The ship he was traveling on was crawling through space, leaving a silver trail like a giant slug. When he focused his gaze on the nearest star, he realized how much work was still ahead to complete the Great Encyclopedia of the Golden Throne and convey the most important truths about the Empire of Mankind. Will he have enough time though...?