The Death Guard are one of the Traitor Legions of Chaos Space Marines. They worship and devote themselves exclusively to the Chaos God Nurgle and as a result of his mutational "gifts" they have become Plague Marines; Astartes who are eternally rotting away within their Power Armour and infected with every known form of disease and decay but who are immune to all pain or minor injury.
Mortarion, also known as the "Pale King," the "Death Lord" or the "Prince of Decay" after he turned to Chaos, was one of the original twenty Imperial Primarchs created by the Emperor of Mankind.
He was given command of the Death Guard Space Marine Legion on the arrival of the Emperor to his homeworld of Barbarus, but he turned to the service of Chaos during the Horus Heresy. At present, Mortarion is the greatest Daemon Prince of Nurgle and the Daemon Primarch of the Death Guard Chaos Space Marines.
He recently returned to Imperial space for the first time in ten thousand standard years when he led the forces of the Plague God in the invasion of the Realm of Ultramar during the Plague Wars.
Unknown Warcry
The Death Guard are one of the Traitor Legions of Chaos Space Marines. They worship and devote themselves exclusively to the Chaos God Nurgle and as a result of his mutational "gifts" they have become Plague Marines; Astartes who are eternally rotting away within their Power Armour and infected with every known form of disease and decay but who are immune to all pain or minor injury.
When the XIVth Legion was first raised on Terra by the Emperor during the First Founding, its Astartes were known as the Dusk Raiders. After the XIVth Legion was reunited with its Primarch Mortarion on the world of Barbarus, he renamed the Legion the Death Guard. The Death Guard are a Traitor Legion entirely steeped in the power of Nurgle, the god of death and plagues, their very essence the epitome of all that vile Chaos God stands for. Their bodies are hives of filth and decay, their flesh eternally rotting away even as it is renewed by the ceaseless process of death and rebirth. Once, however, the Death Guard were the strongest and most resilient of all of the Emperor's Space Marine Legions, the inheritors of the Primarch Mortarion in whose genetic image they were created. Mortarion grew to maturity on the world of Barbarus, a planet steeped in a toxic miasma where the human population cowered in the dark lowlands, fearful of the overlords that preyed upon them from their mountaintop keeps deep within the fog. History does not record who or what these beings truly were, but it is certain they were more than, or at least other than, human. For one, they were able to breathe the deadly gases that make up the atmosphere, getting ever more deadly the higher the altitude, but they are said to have displayed other abilities too.
The abominable masters of Barbarus were somehow able to enslave or dominate the flesh of the dead, and they preyed upon the cringing natives in the valleys below, ever needful of raw material to fuel the endless wars they fought against one another. The infant Primarch was raised by one such overlord, Necare, the greatest of them all, who taught him the ways of war, yet would not answer his questions regarding the people who dwelled in the lowlands. When Mortarion defied his master and descended through the fog, which as a superhuman Primarch he could breathe, he found people, like himself, if weaker and existing in perpetual terror of the overlords who preyed upon them each night.
Though they were initially suspicious of him, Mortarion proved himself one of their kind, and moulded them into an army that at first defied the hunting parties of the overlords, and then turned the tables upon them. At length, the only one left was he who had been Mortarion's master, the High Overlord Necare, residing so high in the toxic strata that not even Mortarion could pursue him. When the Emperor came to Barbarus, the people greeted him as their saviour, yet Mortarion was jealous and resentful of the adulation heaped upon this perfect stranger. Though his people could see that the Emperor was the Primarch's sire, he himself saw only the differences.
Mortarion accepted the Emperor's challenge and ascended into the toxic clouds, higher than he had ever travelled before. At length, he reached the grim keep of Necare and raged for the high overlord to face him. Yet, even the Primarch's superhumanly enhanced body could not withstand the toxic atmosphere, but as he succumbed with Necare about to slay him, he saw the golden figure of the Emperor step between him and the high overlord, entirely unaffected by the poisonous air. With a single stroke of his mighty, flaming blade, the Emperor felled the last overlord of Barbarus, and Mortarion acceded to his fate. Yet the Primarch found himself riddled with anger and resentment at his father for stealing away what he believed to be his rightful vengeance.