Great Scouring

This article is about the Imperial campaign; for the Tau campaign, see Campaign of Scouring.

Great Scouring The Dark Angels and Iron Warriors battle in the Battle of Exyrion during the Great Scouring.[14] Conflict Long War Date *015.M31 - 021.M31 (7 years)[17] *Continued fighting against holdouts for over a century after.[5] Location Imperium Outcome Loyalist Victory *Imperial territory purged *Traitor remnants flee Combatants Imperium Chaos (led by the Traitor Legions): Empire of Iron Colchisian Satrapy Carrion Realms New Mechanicum Commanders Lord Commander Roboute Guilliman (WIA) Primarch Lion El'Jonson (WIA) Primarch Jaghatai Khan (MIA) Primarch Rogal Dorn (MIA) Primarch Corvus Corax Primarch Vulkan Primarch Leman Russ First Captain Ezekyle Abaddon Primarch Lorgar Primarch Angron Primarch Magnus Primarch Fulgrim Primarch Perturabo Primarch Mortarion Primarch Konrad Curze (KIA) Primarch Alpharius (KIA?) Strength Ultramarines Dark Angels Imperial Fists Blood Angels Space Wolves Raven Guard Salamanders White Scars Adeptus Mechanicus Loyal Imperial Army Officio Assassinorum Sons of Horus Word Bearers World Eaters Thousand Sons Death Guard Emperor's Children Night Lords Iron Warriors Alpha Legion Dark Mechanicum Traitor Titan Legions Daemons Traitor Imperial Army Cultists Mutants Casualties Extremely heavy Extremely heavy

The Great Scouring was the Imperium's counter-offensive against the rebel armies of Horus, following the defeat of the Horus Heresy in c.M31^[1]. Horus's campaign to strike towards Terra to achieve a quick and decisive victory had ultimately been defeated. The rebels were broken and in retreat, and Imperial forces now had the job of reacquiring all the territory they had captured. The Great Scouring saw the first mass galaxy-wide purge carried out by the Imperium as it sought to erase the taint of Horus's treachery from its realm.^[1]

It took seven years for the Imperium to drive most of the Traitors into the Eye of Terror,^[17] but the bulk of the Night Lords,^[13] Emperor's Children,^[5] and Alpha Legion^[6c] continued to operate in Imperial space far beyond this date. Large-scale battles are known to have been waged against Traitor holdouts for over a century.^[5]

Overview

The Scouring began immediately upon the relief of the Siege of Terra by a massive reinforcement armada led by Ultramarines Primarch Roboute Guilliman and the death of Horus in his duel against the Emperor aboard the Vengeful Spirit. Immediately upon Horus' death, the Traitor horde fell into a state of confusion, panic, and disarray and made a desperate escape attempt from Terra as Guilliman decimated their orbiting fleet. Guilliman set foot on the throneworld shortly after, meeting with the surviving loyalist Primarchs: Rogal Dorn, Jaghatai Khan, Vulkan, Leman Russ, and Lion El'Jonson.^[16a] They then destroyed what remained of the Traitors on Terra, and even before the fighting was done Guilliman and Rogal Dorn organised the Grand Council of Reconstruction within the ruined Imperial Palace.^[16b]

Even as the Loyalists battled across Terra and its orbit, in the Council issues arose almost immediately. Rogal Dorn along with Leman Russ and The Lion wished to conduct a swift and vengeful pursuit of the Traitors fleeing the Sol System, while Guilliman wished to consolidate their holdings and rebuild their strength while taking strategically important assets such as Luna and Mars. Ultimately, thanks to support by the newly empowered High Lords of Terra, Guilliman's position prevailed and the Ultramarines focused on retaking Luna while the Dark Angels cleared out the last pockets of resistance on Terra and the Space Wolves focused on securing the Sol System and besieging Mars.^[16c] However, after suspicious Iron Warriors warp-based activity was discovered by the Imperial Fists on Neptune's moon of Laomedeia, Dorn launched a renewed offensive anyway and ignored Guilliman's strategy.^[16d]

By 015.M31 the Traitors had been driven from the Sol System, and a year later an angry and vengeful Rogal Dorn launched his Crusade to scour the enemy from the face of the galaxy.^[17]

During the Scouring all records and memory of the Traitor Legions were to be expunged from the Imperial archives. Worlds such as Isstvan V and Davin would be scoured and the Traitors' associated troops were to be destroyed or driven into the Eye. It would be as if the Traitor Legions never existed. Meanwhile since the death of Horus, the Traitor Legions had become splintered and dispersed.^[4]

Fighting continued for years before the rebels were wholly destroyed or exiled. The Imperium fought not only the traitors but also Xenos that had taken advantage of the turmoil caused by the Heresy to plunder human worlds. Systems once thought unassailable to the Xenos threat were put under siege. During the campaign, loyalist forces realized the sheer scale of Chaos influence in the Imperium as world after world was discovered to have traitor presence.^[3] Many corrupted systems were cleansed and placed under the watch of the Inquisition. Horus's death had not ended the fighting, it had renewed the loyalists against the rebels. Many worlds during the Heresy had refused to commit their forces to either side, or seceded entirely. Such indecision was punished by loyalist and rebel alike. These forces were bled white attacking rebel strongholds. Meanwhile, the Legions destroyed at the Drop Site Massacre were slowly reestablished using what little gene-seed the survivors had managed to escape with.^[2]

With the Emperor confined to the Golden Throne and the Imperium leaderless but loosely organised under Roboute Guilliman, the forces of Chaos and all of the enemies of the Imperium swept down on the defenceless worlds which had been ravaged by the fighting during the Heresy. The light of the Great Crusade was gone to be replaced by a dark time in which death was far more prevalent and hope seemed far away. The forces of the Imperium were reorganised and redeployed and gradually the followers of Chaos were forced to flee west to the Eye of Terror. Eventually the Imperium succeeded in stabilising itself, but not without heavy losses of men and machinery.^[2]

The Ultramarines were a major factor in the success of the Imperium owing to their not taking part in the Siege of Terra due to fighting in the galactic east. Roboute Guilliman was the greatest military strategist alive and rallied the other Space Marine Legions to act as a bulwark against all enemies of the Imperium. The days following the Heresy were to be some of the darkest seen since the Emperor rose to power. Guilliman was said to have been everywhere during this period, rallying forces and reinforcing them with his Ultramarines before moving on to the next battle zone. Never once did the Space Marines take a step back, so strong was their faith in the Imperium and Guilliman's tactics.^[5]

During the Scouring, great political changes were introduced into the Imperium, primarily overseen by Guilliman. The most significant of these was breaking apart the Space Marine Legions into Chapters as well as dividing the Imperial Army into the Imperial Guard and Imperial Navy. Both of these measures were intended to curb the power that any single man could wield in the Imperium, limiting the damage if another rebellion broke out.^[4]

The Great Scouring was followed by the period known as the Age of Rebirth.^[1]

Notable events during the Great Scouring

Dated

• 014.M31: The Retaking of Luna, The first battle of the Scouring.^[16c][17]
• 015.M31: The Liberation of Mars, Mars is retaken by the Imperium.^[16c][17]
• 016.M31: The Battle of Avellorn.^[17]
• 016.M31: The Battle of Gamma-Horgan.^[17]
• 017.M31: The Underworld War on Calth ends.^[17]
• 017.M31: An unknown force destroys much of the Nostramo Sector.^[12]
• 017.M31: The Scouring of Molech.^[17]
• 017.M31: The Battle of Seraphina.^[17]
• 017.M31: The Ariggata Culling.^[17]
• 017.M31: The Second Battle of Vanaheim.^[17]
• 018.M31: Operation Carthage. Loyalist forces scour Isstvan V.^[17]
• 019.M31: The Doom of Valhalla
• 019.M31: In a battle known as the Iron Cage, the Imperial Fists take heavy losses assaulting Perturabo's trap on Sebastus IV.^[8a][17]
• 019.M31: The Siege of Olympia. The Iron Warriors homeworld is besieged.^[17]
• 019.M31: The Third Battle of Paramar.^[17]
• 021.M31: The bulk of Traitor forces are driven into the Eye of Terror.^[17]
• 030.M31: The Bitter War on Colchis concludes with the fall of the Word Bearers homeworld.^[6a]
• 121.M31: Roboute Guilliman is mortally wounded by Fulgrim during the Battle of Thessala and put into stasis.^[5]

Undated

• Lion El'Jonson goes missing following the destruction of Caliban and the Dark Angels begin their hunt for the Fallen.^[8c]
• The Plague World Seption Prime is destroyed by Exterminatus.^[10]
• The Salamanders under Vulkan himself attempt to hunt down Fabius Bile for his crimes.^[11]
• The Dark Angels and Blood Angels drive the forces of Chaos from the Cadian Sector.^[10]
• Alpharius or Omegon is believed to be killed by Roboute Guilliman on Eskrador, but the twin Primarch's fate remains unclear.^[6c]
• Jaghatai Khan is thought lost in the Webway during battles against Dark Eldar raiders in the Yasan Sector.^[9]
• The Night Lords launch numerous ambushes that take a high toll on their Imperial pursuers.^[10]
• While leading a genocidal rampage across the Eastern Fringe, Konrad Curze is killed by an agent of the Officio Assassinorum.^[7b]
• Decades after the Horus Heresy and years after Curze's death, the Night Lords' main force is defeated by an Ultramarines-led coalition in the Battle of Tsagualsa. The Night Lords are shattered as a Legion.^[13]
• Rogal Dorn leads the Imperial Fists against the Iron Warriors on Hevaran.^[15]
• Rogal Dorn is thought killed in a Black Crusade.^[7a]
• The Battle of Exyrion between the Dark Angels and an alliance of Iron Warriors and Fallen.^[14]

Sources

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• 1: Warhammer 40,000 5th Edition Rulebook, pg. 124
• 2: Realm of Chaos: Slaves to Darkness, pg. 243
• 3: Warhammer 40,000 6th Edition Rulebook, pg. 161
• 4: Warhammer 40,000 7th Edition Rulebook - The Age of the Imperium
• 5: Nightbringer (Novel) - The Ultramarines Omnibus, Chapter Two, pg. 49
• 6: Index Astartes IV:
  • 6a: Dark Apostles - The Word Bearers Space Marine Legion
  • 6b: Sons of Horus - The Black Legion Space Marine Legion
  • 6c: The Enemy Within - The Alpha Legion Space Marine Legion
• 7: Index Astartes II:
  • 7a: Imperial Fists
  • 7b: Bringers of Darkness - The Night Lords Space Marine Legion
• 8: Index Astartes I:
  • 8a: Bitter and Twisted - The Iron Warriors Space Marine Legion
  • 8b: Children of the Emperor - The Emperor's Children Space Marine Legion
  • 8c: The Unforgiven
• 9: Codex: Space Marines (8th Edition), pg. 34
• 10: Codex: Dark Angels (8th Edition), pg. 10 - Dark Heritage
• 11: Codex Supplement: Salamanders (8th Edition), pgs. 24-25
• 12: The Horus Heresy Book Six - Retribution, pgs. 136–144
• 13: Void Stalker (Novel), Chapters 12-14
• 14: Will of Iron (Comic Series), Issue #1
• 15: Helbrecht: Knight of the Throne (Novel), Chapter 3
• 16: Ashes of the Imperium (Novel):
  • 16a: Chapter 2
  • 16b: Chapter 9
  • 16c: Chapters 17-18
  • 16d: Chapter 39
• 17: Warhammer Community: The Scouring timeline – How the Warhammer Studio worked with Black Library authors on the new series (archived from the original 12 March 2026, last accessed 12 March 2026)