If there’s one thing Horus Lupercal’s rebellion proves, it’s that even betrayal can be meticulously organized.
Before a single shot was fired at Isstvan III, Horus already had a spreadsheet of destruction in hand. His opening play wasn’t random carnage—it was calculated removal. Every Loyalist Legion posed a potential obstacle to his goal of reaching Terra, and he wanted them scattered, isolated, or dead before they could unify.
So, where were the Loyalist Legions when the galaxy started burning? The short answer: everywhere except where they needed to be. The long answer? Let’s dive in.
Dark Angels – Removed From the Board
The Lion wasn’t subtle. Horus knew he’d never be able to turn the Dark Angels, so he simply had them shipped off across the galaxy under official orders. By the time they got wind of the Isstvan Massacre, the Heresy was well underway. The Dark Angels spent the next several years fighting to get back to Terra, their fury growing with each campaign.
White Scars – A Mysterious Enemy at Chondax
Jaghatai Khan and his White Scars were mopping up an Ork infestation on Chondax when they ran into the Alpha Legion. Sneaky, yes—but very much on purpose. The Khan, never one to sit idle, broke the blockade and headed for Terra. He would eventually arrive in time to take part in the climactic siege.
Space Wolves – Censure Turned Slaughter
Russ and his wolves were dispatched to bring Magnus to justice after the fiasco at Prospero. But thanks to Horus’ manipulation, justice became annihilation. Prospero was left in ruins, Magnus fled to the Warp, and the Wolves were left with blood on their hands. Upon realizing Horus’ betrayal, Russ swore vengeance, setting his sights on the traitors.
Imperial Fists – Builders of the Bastion
While others were duped or deployed, Rogal Dorn and the Imperial Fists were brought to Terra directly by the Emperor himself. Their role was simple but crucial: build the fortress that would become the Emperor’s last redoubt. Dorn attempted to send forces to Isstvan in response to the betrayal—but they were ambushed at Phall by the Iron Warriors. Still, the Fists would anchor the final defence in the Solar War.
Blood Angels – Trapped in a Warp Nightmare
Horus lured Sanguinius and the Blood Angels to Signus Prime, where they encountered a Warp-infested hellscape. The goal? Break them. Sanguinius clashed with the Daemon Kha’bandha, a fight that left lasting scars on him and his sons. Once they escaped, the Blood Angels began their grim march toward Terra, changed forever.
Iron Hands – The First to Die
Ferrus Manus didn’t hesitate. Outraged at Fulgrim’s betrayal, he and his Iron Hands went in at full strength to Isstvan V. What awaited was the Warmaster’s trap. Ferrus died, his elite forces were annihilated, and the Legion was shattered. The remnants regrouped in fragmented cells, waging a bitter war of revenge.
Ultramarines – Cut Off by the Ruinstorm
Roboute Guilliman had numbers—lots of numbers. That alone made him a threat. Horus used Word Bearer treachery to trap the Ultramarines at Calth, where they were devastated in a surprise attack. But the worst blow was the creation of the Ruinstorm, which cut Guilliman off from Terra. He turned inward, fortified Ultramar, and rebuilt—but he couldn’t rejoin the wider war until much later.
Salamanders – Broken but Burning
The Salamanders went in with the Iron Hands and Raven Guard at Isstvan V. They were among the first to land and among the first to bleed. Vulkan was presumed dead, and the Legion’s strength was decimated. Yet survivors remained and fought on, often alongside the other shattered Legions. Vulkan’s survival would prove vital later on Terra.
Raven Guard – Ghosts of the Drop Site
Corax and his Raven Guard were never built for massed assault, but they answered the call anyway. After the massacre, they were nearly wiped out. Instead of fading into history, they waged a brutal guerilla campaign against the traitors. Meanwhile, Corax sought forbidden methods to rebuild his Legion—methods that would come at a cost.
A Masterclass in Pre-emptive Chaos
The genius of Horus’ plan wasn’t just its brutality—it was its timing. Before any major Loyalist Legion could meaningfully respond, they were either fighting on distant fronts, reeling from betrayal, or slogging through Warp storms. Ferrus was dead. Guilliman was boxed in. Russ was bled dry. The Salamanders and Raven Guard were shadows of themselves. Only Dorn had been positioned to act defensively from the start.
And that wasn’t luck. It was strategy, as cold and cruel as any blade wielded during the war to come.
Final Thoughts – Before the Fall, the Separation
Next time, we’ll explore the other side of the coin—what the traitor Legions were doing as Horus pulled the strings. For now, the takeaway is simple: before the Heresy began in earnest, Horus had already fractured the Imperium’s defenders. That was the only way this war could even begin, let alone reach Terra.
Don’t miss the follow-up deep dive on the Traitor forces. And if you’re not already signed up for the Warhammer Newsletter, now’s the time—especially with that prize draw for your favourite Primarch mini still open.
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