The Suppression of the Macharian Heresy was a notable Imperial military campaign conducted by the notoriously savage Minotaurs Space Marine Chapter following the death of Lord Commander Solar Macharius in 400.M41 and lasting until approximately 470.M41. After the death of Macharius, those great demesnes that he had conquered for the Imperium of Man during the Macharian Crusade fell into open civil war and anarchy between his seven former Imperial Guard Army Group generals throughout the newly-conquered territories. These contested territories splintered into petty star empires, each lorded over by one of Macharius' old generals who had repudiated their oaths of loyalty to the Imperium, opposing each other as well as the authority of the Adeptus Terra, and with Space Marine Chapters now drawing sword upon each other in dispute and anger, the High Lords of Terra were forced to act decisively.
This they did by calling in several waves of fresh Space Marine Chapters to bring the civil conflict to an end by exterminating heretical forces and bringing order to the region under the command of the Imperial Warmaster Solon. Ultimately, the forces of over 100 separate Chapters were deployed at some point during the campaign. One such Chapter operating under the High Lords' writ was the Minotaurs, then a Chapter all but unseen for millennia. They were a Chapter both familiar through their fell reputation and profoundly changed. A fleet-based Chapter, operating fully equipped and at peak strength, the Minotaurs fought as a single cohesive force that struck like a series of brutal axe blows at sources of schism and disorder, quickly earning themselves a bloody reputation by carrying out the orders of the High Lords without question or falter.
During the suppression, it was the Minotaurs who formed the spearhead of the battle group which shattered the petty-empire of the outlaw Colonel Lyrias of the 11th Kahdu Armoured Corps, their Chapter's Land Raiders blasting apart the famed tanks of the elite Kahdusine "Immortals" on the ice plains of Gyros Prime. They also carried out Exterminatus orders on the Hive World of Duval and the Sword Realms of the Hope Cluster. While on the Ocean World of Nereus they hunted down and obliterated the xenos-possessed remnants of the Imperial Paladins Chapter's 4th Company in the mazes of the sub-surface cavern cities, poisoning the seas of that once vital Agri-World. The suppression of the Macharian Heresy would take seventy standard years before order was restored under the command of Warmaster Solon to the affected regions of the Segmentum Pacificus, with operations ending around the year 470.M41.
The Euxine Incident
The action from which the Minotaurs gained the most infamy during the Macharian Heresy would be known as the Euxine Incident, which resulted in the near-destruction of two Imperial Space Marine Chapters who had become locked in conflict. These Chapters were the Doom Warriors and the Inceptors. Formerly allies in the Macharian Crusade, they had come to blows over a matter of honour and were embroiled in a long running and highly protracted conflict fought under predetermined rules of engagement in the Euxcine System. With the two combatant Chapters refusing calls to end their battle and aid with the pacification, the Minotaurs were dispatched to sunder the two apart and end the strife.
Caring nothing for the causes or rights of the two Chapters, the Minotaurs attacked in full force with their initial strike. Overmatched and broken, the Doom Warriors fled the system almost immediately in a barely organised retreat, however with most of their warships either destroyed or captured in orbit, the Inceptors found themselves trapped on Euxine before the Minotaurs' wrath. Relentlessly and systematically the honoured Second Founding Chapter was encircled and slowly destroyed piece by piece, until the last remaining Inceptors Space Marines were forced into a humiliating surrender as fewer than 100 Battle-Brothers had survived. To add further insult to their ignominious defeat, the Minotaurs stripped the fallen of many relics for their own armouries and took the ravaged Chapter's flagship, a Great Crusade-era assault transport that had served the Inceptors since their Founding, as a spoil of war.
That such an ancient and revered Chapter and close scion of the Ultramarines could be almost annihilated in this fashion, and with the tacit agreement of the High Lords, sent shock waves through many of the Space Marine Chapters who came to hear of it. The Minotaurs were denounced across Ultramar for their atrocities and forbidden to enter its bounds. Others of Roboute Guilliman's line have since sworn vengeance on the Chapter should the opportunity arise and honour permit them to carry it out. Their task completed, the Minotaurs withdrew from the region in 425.M41.
The Star Phantoms
Another infamous Space Marine Chapter that took part in the Macharian Crusade was the morose Star Phantoms. This Chapter participated in many of the Macharian Crusade's most deadly engagements, and despite having proved themselves time and again, they garnered little respect as they saw matters, and are known to have had a troubled relationship with the Crusade's commanders as to strategy and deployment.
After the death of Lord Commander Solar Macharius they became swiftly embroiled in the Macharian Heresy as they clashed directly with those Imperial Guard forces who in the Chapter's view had betrayed the Imperium. The Star Phantoms are listed in certain suppressed sources as being directly responsible for the annihilation of the 17th Terrax Guard on Thoth, and are known to have engaged in a bloody and protracted conflict with their former allies, the Marines Malevolent, resulting in that Chapter's near-destruction at their hands. The Star Phantoms became subject to Inquisitorial investigation as a result of their actions and were ultimately cleared of heresy, but received censure from the Ordo Hereticus.
They were bound into the thankless and dangerous task of partly forming the spearhead of the Imperial Interdiction campaign in the 070s.M41 to end the Macharian Heresy. In the aftermath of this short and brutal campaign which involved elements from over 100 Space Marine Chapters, the Star Phantoms, once again badly reduced in strength, undertook a self-appointed Crusade alone in the southern Segmentum Tempestus attacking isolated Ork and Chaos-held worlds as they saw fit. Much of their activities afterward remained hidden both from the official record and the eyes of the Imperium until their participation in the brutal closing stages of the Badab War.
The Dark Angels
Over three standard decades beginning in 405.M41, the Dark Angels were one of the Space Marine Chapters tasked with suppressing the civil wars collectively known as the Macharian Heresy that were ongoing across many of the territories gained by the Imperium during the Macharian Crusade of the Lord Solar Macharius. The Ravenwing uncovered several corrupt Chaos Cults, largely instigated by the Alpha Legion, and the unmistakable signs of the Fallen Angel Cypher's presence. During the Lythanos Uprisings, only a run-in with the Space Wolves, the Dark Angels' ancient rivals, allows several of the Fallen to escape the Dark Angels' grasp.
- Codex: Dark Angels (6th Edition) pp. 36-38
- Codex: Imperial Guard (5th Edition), pg. 13
- Codex: Imperial Guard (2nd Edition), pg. 87
- Imperial Armour Volume Ten - The Badab War - Part Two, pp. 107, 109, 134