Not everyone is a readymade Horus Heresy expert, and with the new edition of the game right around the corner, you may find yourself wondering what’s up with this foundational chunk of Warhammer lore.
What was the Horus Heresy?
This is a vital period in the Warhammer 40,000 universe which has captured the minds of fans for more than a generation, spawning numerous games, novels, artwork, animations and more.
The Horus Heresy is the foundation myth of Warhammer 40,000. It’s a series of devastating events set roughly 10,000 years before the current timeline which forever reshaped the galaxy and built the brutal horror of the Imperium of Man.
While the contemporary setting in Warhammer 40,000 – the Era Indomitus – takes place at the closing years of the 41st Millennium, the Horus Heresy occurs at a more optimistic time: the end of the Great Crusade. This is when the nascent Imperium set off from Terra and attempted to reunify untold thousands of scattered human colonies after millennia of galactic turbulence.
We need to step back and quickly look at a rough* timeline of mankind’s history, bear with:
Millennia 1-15
The Age of Terra: Humanity dominates Old Earth and colonises the Solar System
Millennia 15-25
The Dark Age of Technology: Humanity begins galactic expansion, creating all manner of technological marvels to aid it. It fights most xenos species, makes pacts with others and generally grows in size and power, becoming a vast interstellar civilisation, until…
Millennia 15-30
The Age of Strife: Two combined factors cripple civilisation. There’s a sudden rise in psykers in human populations across the galaxy, which causes a dramatic increase in the incidence of Warp-related disasters, including daemonic incursions. Meanwhile, man’s reliance on abominable intelligence eventually results in a revolt from its armies of automata and a devastating civil war. Civilisation collapses and countless thousands of worlds fall into ruin or are enslaved by alien species. Terra, the cradle of humanity, is cut off from the galaxy, becoming little more than a wasteland ruled by techno-barbarian warlords. Misery and suffering are universal.
At the end of this period, a figure emerges to unite Terra. This is the Emperor, an immortal who had been biding his time to strike. He conquers the planet with his armies of genetically modified Thunder Warriors, a struggle which takes centuries.
Millennium 30
The Great Crusade: With Terra unified, the Emperor replaces his armies of Thunder Warriors with the Legiones Astartes, the Space Marines, who are led by the Primarchs – demigod-like beings who were in many ways his sons. Over the next centuries, the Space Marines conquer much of the galaxy, crushing or driving off alien civilisations and bringing lost human worlds into compliance.
The Emperor withdraws to concentrate on plans that will benefit all mankind. He leaves Horus, the greatest of his sons, as Warmaster to continue the work of reconquering the galaxy.
The Horus Heresy: Horus is seduced by the Chaos Gods. He turns against the Emperor and convinces half the Space Marine Legions to side with him. What follows is the most brutal war in humanity’s history. Trillions die as Horus and his allies advance on Terra and besiege the Emperor’s palace. Ultimately, Horus is defeated, but the Emperor also is mortally wounded, enshrined upon the Golden Throne in a permanent state of undeath.
There’s an excellent account of this in the first three novels in the Horus Heresy series from Black Library. These tell how Horus, having attained the glory of being the Emperor’s Warmaster, was lured from the path, and how nine Space Marine Legions were compromised – infiltrated by insidious warrior lodges and swayed from the path by cunning individuals who spread discontent, malice and jealousy enough to ferment an open rebellion.
The concluding events of the Horus Heresy are beautifully described in the the Siege of Terra sequence – which are some of the finest Warhammer novels ever written. They describe how the Warmaster’s Legions smash their way into the Sol System, and batter through every defence the remaining loyalists can erect – and ultimately through the walls of the Imperial Palace.
With victory almost in his grasp, yet unable to break the defenders and take on the Emperor himself, Horus learns that long-awaited Imperial reinforcements are but days away from Terra. In a desperate gambit, he lowers the shields of his flagship, challenging the Emperor to personal combat. Horus is slain, but the Emperor is so mortally wounded that his aides ensconce him upon the Golden Throne – and his death’s-door existence can now only be sustained through the sacrifice of thousands of psychically attuned individuals every day. For 10,000 years.
Everything the Emperor and his followers had fought for is tainted… an Imperium founded on rationality rapidly begins to resemble a death cult, first honouring then worshipping the Emperor as a god. The traitors, initially scorned and defeated, are scoured from the galaxy for a time, only to regroup and prepare for their long war.
How is it different to Warhammer 40,000?
These settings feature many of the same locations and even, in a few cases, characters – despite being divided by 10,000 years.
The Horus Heresy occurs at a time of humanity’s highest hopes. With the Space Marine Legions and the mighty fleets of the Great Crusade, it feels like the Imperium has a chance for victory.
But the Horus Heresy irrevocably ruins all of that.
By the 41st Millennium, the Imperium has become a superstitious shadow. Fear and ritual dominate every aspect of life, and the vast bureaucracies of the Adeptus Ministorum (the Imperial Cult) and the Adeptus Administratum (essentially a titanic administrative body) control almost everything. Many advances in technology are lost, and the few that are made anew come at appalling cost. Life is brutal, and the fractured Imperium survives under constant threat of aliens, mutants, the Traitor Legions and worse…
Keep checking back to Warhammer Community, which will be packed with more Horus Heresy content over the coming weeks, and make sure you’re subscribed to our email, so you never miss an update.
* You can learn more about all these events in the Warhammer 40,000 Core Book, and the forthcoming Warhammer: The Horus Heresy rulebook.
