Alpharius Omegon, Primarch of the XXth Legion, the Alpha Legion, was not one Primarch but two: twin brothers who hid their nature from almost everyone. The youngest sons of the Emperor were masters of secrets and lies, and their reasons for joining Horus remain one of the great mysteries of Warhammer 40,000.
Alpharius Omegon at a glance
| Primarch of | the XX Legion |
| Legion | XX: Alpha Legion |
| Homeworld | Unknown. The Legion has never said, and every story conflicts |
| Symbol | The Hydra |
| Wargear | The Pale Spear (Alpharius) |
| Allegiance | Traitor (but for reasons of their own) |
| Fate | Alpharius reported killed; Omegon unknown |
Who is Alpharius Omegon?
Alpharius and Omegon are the twin Primarchs of the XXth Legion. They looked exactly alike and shared the command, one acting in public as Alpharius while the other, Omegon, worked in the shadows. Only a few people outside the Legion ever knew there were two of them. Everything about them is uncertain, by design. Even the Alpha Legion's warriors are trained to lie about who they are. If you ask a member of the Legion his name, he may simply answer: "I am Alpharius."
Origins: a deliberate mystery
Nobody outside the Legion knows where the twins grew up. Imperial records give several different homeworlds, and the Alpha Legion has never confirmed any of them. Some stories say they were raised among soldiers, others that they grew up in secret. The truth may never be known, and that suits the Alpha Legion perfectly.
The last sons found
Alpharius was the last Primarch to be reunited with the Emperor. In most accounts, he was not found at all: he came to his father. When the Emperor's fleet arrived in his region of space, Alpharius approached on his own terms, ready to join the Great Crusade. The Emperor gave him the XXth Legion and placed him under the guidance of Horus for training. Alpharius admired Horus deeply, which would matter later.
The Alpha Legion
The XXth Legion was the youngest and smallest of the Legions, but the most cunning. Its warriors were all very similar in height and build, chosen to look like their Primarch, and they wore the same armour without obvious marks of rank. That made it almost impossible for an enemy to tell who was in charge. Officers like Armillus Dynat and the infiltration expert Sheed Ranko worked alongside a huge network of spies, cultists and agents planted on other worlds.
The Legion's symbol is the Hydra, a monster that grows two heads for every one that is cut off. It describes them exactly: kill one leader and two more take his place.
How the Alpha Legion fight
The Alpha Legion win wars before they start. They plant agents years in advance, start uprisings, cut supply lines and turn the enemy's own people against him. When the Legion finally strikes, it often comes from a direction nobody expected. During the Great Crusade, Alpharius once tried to prove his Legion's methods were better than those of Rogal Dorn and Roboute Guilliman, which earned him rivals among his brothers.
The Cabal and the choice
The novel Legion gives the best-known explanation of why the twins turned traitor. A secret alliance of alien races, the Cabal, showed them two futures. If the Emperor won the Heresy, they said, humanity would one day fall to Chaos and the whole galaxy would burn. If Horus won, humanity would be destroyed, but Chaos would be starved and the galaxy would survive. Alpharius and Omegon chose to side with Horus, not because they believed in Chaos, but because they believed it was the lesser evil.
Nobody knows whether the Cabal told the truth, or whether the twins really trusted them. Some stories hint that the Alpha Legion have their own plan, one that works for no one but themselves.
Isstvan V and the Heresy
At the Drop Site Massacre on Isstvan V, the Alpha Legion was one of the four Legions of the second wave that turned on the loyalists. During the rest of the Heresy, it fought a long, hidden war. Its most famous campaign was against the Raven Guard of Corvus Corax, striking at Deliverance while Corax tried to rebuild his Legion. The Alpha Legion also fought the Ultramarines and the Imperial Fists, often in ways nobody else could follow.
The death of Alpharius
Accounts of what happened to Alpharius disagree. The most widely told story in Horus Heresy lore is that Rogal Dorn hunted him down and killed him in battle on the world of Pythos. Older Imperial records claim that Guilliman killed him after the Heresy. The Alpha Legion simply smiles at both stories. Omegon's fate is completely unknown, and Imperial reports keep claiming to have seen Alpharius on battlefields thousands of years later.
The Alpha Legion today
In the 41st Millennium the Alpha Legion is still active, and still impossible to pin down. It runs cults and spy networks on Imperial worlds, sometimes fights alongside other Chaos forces and sometimes against them. A few of its warriors even seem to help the Imperium, for reasons nobody understands. The Legion's motto is "Hydra Dominatus".
On the tabletop, the Alpha Legion is one of the most popular Chaos Space Marine Legions, because its warriors can be painted and played in so many ways. Read our Chaos Space Marines lore guide for more about the traitor Legions today.
Personality and brothers
Alpharius and Omegon were calm, clever and very hard to read. They respected Horus more than any of their brothers. They were rivals with Guilliman and Dorn, and their war against Corax made the Raven Guard their bitterest enemies. Whatever their true goal, they kept it to themselves.
Alpharius Omegon FAQ
Are Alpharius and Omegon two people?
Yes. They are identical twin Primarchs who shared command of the Alpha Legion.
Why did the Alpha Legion join Horus?
In the novel Legion, the alien Cabal convinced them that a Horus victory would save the galaxy from Chaos in the long run.
Who killed Alpharius?
Most Horus Heresy sources say Rogal Dorn killed him on Pythos. Older records credit Guilliman. Omegon's fate is unknown.
What does "I am Alpharius" mean?
Alpha Legion warriors claim to be Alpharius to confuse enemies and protect their real leaders.
Are the Alpha Legion really traitors?
They fight for Chaos, but their true goals are a mystery. Even other traitors do not trust them.
Books to read
- Legion (Dan Abnett)
- Alpharius: Head of the Hydra (Rob Sanders)
- Deliverance Lost (Gav Thorpe)
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Find them as Black Library paperbacks and audiobooks.
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