The Plague Wars

In the terrible days after the Great Rift split the galaxy asunder, the plague-ridden legions of Nurgle fell upon the realm of Ultramar. At their head marched the Daemon Primarch Mortarion and his Death Guard, come to drown the Ultramarines' home in pestilence and offer it up to the Lord of Decay. The struggle that followed, the Plague Wars, would pit brother against brother and become one of the defining conflicts of the new age of darkness.

Nurgle's Design on Ultramar

The war was no mere raid but a campaign of conquest with a monstrous purpose. The forces of the Plague God sought to seize Ultramar entire and transform it into a new dominion of rot, a realm of realspace to be grafted onto the nightmarish Garden of Nurgle.

Ultramar was a prize of great symbolic worth. As the shining jewel of the loyalist Space Marines and the home of Roboute Guilliman himself, its corruption would strike a devastating blow against the Imperium's morale as well as its strength. For Mortarion, there was a bitter satisfaction in defiling the realm his loyal brother held most dear.

The Death Guard Descend

Mortarion, once a primarch of the Emperor and now a bloated servant of Chaos, led the invasion in person. His Death Guard spread contagion before them, unleashing engineered plagues and daemonic infestations that withered worlds and turned their populations into shambling, pox-ridden horrors.

World after world of Ultramar was assailed, their defences strained to breaking by the relentless tide of decay. The Plague Wars ranked among the very first great conflicts of the era born from the Great Rift, and for a time it seemed the whole of the Ultramarines' realm might rot from within.

The Realm Beset

Against this horror stood Roboute Guilliman, newly returned to the living and now Lord Commander of the Imperium. Casting aside grander strategies to defend his own people, the primarch led the counter-offensive to purge the plague from his home realm and cast the invaders back into the void.

Guilliman's forces fought across dozens of worlds, contesting every league of ground against an enemy that felt no fear and shrugged off wounds that would fell any mortal soldier. The war became a grinding campaign of attrition, fought amid ruined cities and fields black with corruption.

The Battle of Parmenio

One of the war's fiercest clashes came on Parmenio, where the largest armoured and Titan engagement of the entire conflict unfolded across the Plains of Hecatone. Rank upon rank of tanks and towering war-engines ground against the plague hosts in a battle of staggering ferocity.

At the height of the fighting Guilliman himself struck at the vanguard of the Great Unclean One Ku'gath, cutting down the daemon's lieutenant Septicus. The battle for Parmenio would prove a crucial trial of strength, testing whether the defenders could stem the rising tide of rot.

The Fall of Galatan

The war was not confined to the surface of worlds. In the void above, the mighty star fort Galatan sought to lend its guns to the defence, only to be boarded by the daemon-haunted vessels of the Plague Fleet.

The fighting within the fortress was a slaughter, and the casualties were grievous — among the fallen was Bardan Dovaro, Chapter Master of the Novamarines. The loss of Galatan was a bitter reminder that even the greatest bastions of the Imperium could be brought low by the servants of decay.

The Reckoning on Iax

The war reached its climax on the garden world of Iax, which the forces of Nurgle laboured to twist into a daemon world of eternal pestilence. The whole campaign there was a trap, laid to slay Guilliman with a bespoke contagion crafted to end even a primarch.

As Guilliman and Mortarion met at last in single combat, loyalist warriors fought to destroy the daemonic cauldron brewing the plague, an Imperial preacher rising to sainthood in the struggle. Struck down and poisoned by his brother, Guilliman hovered between life and death — and returned, infused with holy power, to deal a grievous wound to the very Garden of Nurgle. Defeated, Mortarion fled the field under cover of a virus-bomb barrage.

Ultramar Restored

With the plot on Iax foiled and its master driven off, the Plague Wars came to an end. Mortarion withdrew the remnants of his legion to the Scourge Stars, his grand design to claim Ultramar for Nurgle undone.

Guilliman turned at once to the long labour of recovery, overseeing the decontamination and rebuilding of his ravaged realm. Amid the ashes he also established new means of raising Primaris reinforcements within the Ultramarines, so that his Chapter and its realm might be restored. Ultramar had endured — scarred, diminished, but unbroken — and the Imperium had proven that even the plagues of Nurgle could be defied.