40K Lore: Barbarus – Home of the Death Guard

Even the soured corrupted hearts of the Death Guard have a soft spot for home – the blighted planet Barbarus.

Barbarus was the homeworld of the Death Guard prior to the Horus Heresy. It was the planet on which Mortarion landed and was of such a poor atmospheric quality that even Mortarion could not breathe at the top of its mountains.


Barbarus was a Feral World which orbited near its dim yellow sun. The atmosphere was thick with virulent gases and a constant fog was spread across the planet. This made it a very dark, dismal place of night with short, shadowy days. Only below the fog could humans survive, in the valleys and low plains.

Beings immune to the toxic fog survived within the toxic cloud and built great grey keeps in the mountains. The higher beings began to use the humans as slaves and spread terror among them, what these creatures were is not certain. After landing on the world, Mortarion eventually led the citizens of Barbarus in a revolt against the mountain rulers, toppling them before joining with the Emperor.

On the surface of Barbarus was the Wall of Memory, where the names of every Space Marine of the Death Guard legion killed during the Great Crusade were carved.

Mortarion Arrives on Barbarus

The only consistent information regarding Mortarion and his homeworld come from a single source: the Stygian Scrolls of Lackland Thorn, a historian and polymath attached to the explorator fleet that discovered Barbarus.

Mortarion crash landed on the world of Barbarus. He came to rest at the site of a huge battle fought across a vast plain. All around him were strewn the bodies of the dead and dying for miles in all directions. Barbarus was constantly covered in a poisonous fog and the mountains were ruled by fierce warlords. The normal humans, dropped off millennia before, were forced to live in the lowest areas of the planet, amidst the choking fog. They were condemned to an endless life of servitude and were in constant fear of those who moved above them.

The winner of the battle in which Mortarion had landed was the greatest of the warlords. He was revelling in his victory until the silence was shattered by the scream of a child. It is said this warlord walked the battlefield for a day searching for the child, not stopping once until he found it. For a moment he considered killing the child, but he realised that no human should be able to breath at this height, let alone cry out. He considered what he had found, and then bundled the child up and carried it from the carnage. He now had a son, something he had craved for years despite his dark magical powers. The warlord christened the child Mortarion, child of death.

The warlord tested how high the child could survive in the poisonous atmosphere of Barbarus and then erected a massive wall of black iron. He then moved his mansion past this to keep it from the child. Perhaps he knew the child was better than him and that one day he would come for the warlord, or perhaps he was afraid of the small child able to breath where no other of his kind could. Whatever he felt, he trained the child in his image. He taught everything of warfare to Mortarion. He was constantly at the front fighting against all of the other warlords’ armies, sometimes of undead humans, sometimes of more daemonic creatures. Mortarion was still human though, and he sought to know of those who dwelled below the layer of fog. Eventually Mortarion escaped from his holdings and descended the mountain, the warlord bellowing after him of his treachery and that to return would mean death.

Barbarus Fights for it’s Freedom

As Mortarion descended, he began to realise he had found his people. He smelt the scent of food for the first time, he saw people unobstructed by the fog and for the first time he heard laughter, real laughter, not that of the victorious warlord’s. He realised that the prey that the warlords fought over was his own people, and with this came a sense of hatred and he vowed to give them justice over their oppressors.

His acceptance into the community of humans was not easy. He was seen as just another monster from above them, and this was quite true due to his appearance. He had pallid skin and hollow, haunted eyes and he terrified most of the inhabitants. He may have been feared, but Mortarion bade his time and helped get the meagre harvest in and was generally a useful and productive member of the society, more than most were. Eventually, the time he had waited for arrived, a way to prove himself in the eyes of his fellow humans.

A lesser warlord had arrived with his shambling undead legions and began to carry off those they could for their master’s plans. The peasants fought back as best they could, but they only had fire torches and farming implements to defend themselves. Each of them had fought many times like this during their lives and it was all they could do not to run, let alone put up an effective counter manoeuvre. Until, that is, Mortarion himself joined into the fray. He strode above his fellow humans, dwarfing all around him. He used an enormous two handed scythe and charged into the ranks of the enemy with the hatred that had been building for years before and drove them from the village. The warlord smiled and withdrew to the poisonous area above, unaware of the primarch’s amazing respiratory abilities. Mortarion dispatched the warlord and his place among the villagers was sealed.

As Mortarion grew he taught the villagers all he knew of warfare. Word of his knowledge and exploits spread and people came from far and wide to learn from him. Soon, villages were becoming strongholds and the villagers were more effective defenders. Eventually, Mortarion began to move from village to village, teaching along the way and if need be, defend the settlements. His ultimate vengeance was always denied to him because of the fog that prevented the humans from pushing home their attacks.

Scions of Barbarus: The First Death Guard

Mortarion then recruited the strongest and most resilient of warriors from the villages he went to. He formed them into elite units and drilled them himself. He turned blacksmiths from tool-working to weapons-making when time allowed and had them craft armour. He also armed his warriors with crude air filtration apparatus. It is said that the next attack that descended from the mountains above was repulsed quickly and Mortarion, leading his Death Guard, as they had become known, followed them into the fog above, massacring the remaining forces and killing the warlord. For the first time in history, Mortarion had led the people into the toxic fog and survived. Mortarion continued to improve the breathing apparatus and campaigned ever higher into the fog. The constant exposure to the toxins hardened his warriors, a useful and transferable skill retained by the Death Guard

Post Heresy

After Horus was defeated, Mortarion led his forces, in an ordered formation, back to the Eye of Terror. Mortarion claimed the Plague Planet as his new world and it is ideal for launching attacks on the real world. He shaped it so well that Nurgle promoted him to Daemon Prince. Mortarion got what he wanted, a world of his own. He ruled over a toxic death world of poison, horror and misery. He had come home.

The ultimate fate of Barbarus is unrecorded.

~ Knowledge is power – guard it well.


  • SALLstice

    I found this article both interesting and informative.
    Any Death Guard player would be delighted to know more about the lore of their army and use this to embolden their strategies in battle.

    • dave long island

      Right on, great article. Love the art at the top, too.

  • petrow84

    That was awesome.
    Some extra lore for you: Mortarion eventually made his world into the shape of Barbarius, however, Typhus was sickened by his sentimentality, and choose not to set foot on the planet ever.

  • Brian Brodeur

    Good read. I woulda liked a short version of what happened afterwards.
    Sounds like he was a good guy building his people up and slaughtering his oppressors ….. I assume the bad juju just corrupted him and his people in the end ?

    • KingAceNumber1

      Basically, he didn’t think that the Emperor went far enough during the Council of Nikea in an effort to control Psykers. He never really liked the Emperor much, as he saw him having stolen his victory over his adoptive father on Barbarus, so it wasn’t hard for Horus to sway him. Mortarion attempted to speak with the Khan and turn him as well, but they ended up fighting when Khan didn’t change sides. Mortarion ends up running a bunch of raids on White Scars turf and eventually encounters a rogue psyker who’s possessed by a demon of Nurgle. The demon shows Mortarion what he’s signed up for and provides him with the knowledge that he’s sided himself with the very thing he hates, the source of the Psyker mutation (the Warp). Mortarion realizes his mistake but it’s too late to go back, so he harnesses his own latent psychic energy and banishes the demon, forever tainting himself. The remainder of his fall happens when the Death Guard gets stranded in the warp and rot for a couple hundred years under the attentions of Nurgle. Mortarion finally dedicates his life and those of his warriors to Nurgle and they’re freed from the warp right at the gates of Terra to meet up with Horus’ siege force.

      • Brian Brodeur

        Awesome. Thanks for the rest of that. Greatly appreciated.

  • Moonman45

    Mortarion, the only traitor primarch that was halfway reliable.

    • Agent of Change

      That’s an interesting statement because as traitors they were all ultimately only loyal to themselves. Whether it was to ideology or honor the thing that made all of the traitor Primarchs turn (and for that matter all of the loyalist to remain loyal) was a choice between themselves are their interests and something greater than themselves.

      You can point to all the various motivations but it really boils down to “I support the Imperium and the dream of the Emperor or I don’t because…[personal grudge/issue]”. That fundamentally makes them all individuals and therefore unreliable. Not a one joined Horus because they truly believed Horus had a vision for a better future, no they ended up joining because of their own greivences petty or otherwise creating an ultimately unreliable alliance untied only as far as the convergence of personal interest. They Rebelled together because it was the only hope to successfully rebel and that ultimately is what the forces of chaos wanted a disunited force at the end of it all.

      So I would argue that depending on what you were talking about that all of the traitor primarchs were no more than half-way reliable to anyone but themselves and all of them were less than that in most cases.

      • James Regan

        Lorgar did it for the betterment of the imperial truth, and Angron genuinely believed it was the right thing to do, even before horus got involved. Fulgrim got possessed, then stuck in a painting for a bit, so while the emperors children did go along with it for selfish personal reasons, those reasons were initially just loyalty to chaos, because, of being you know, a chaos daemon.

        Whilst the reasons can be seen as a bit odd, Lorgar believed in the gods- he wasn’t using religion as an excuse for personal gain, he thought the emperor and his imperial truth were wrong, and therefore bad, and therefore he was doing the right thing. Angron explains that the only reason he didn’t rebel earlier is because he is not a good man- yeah he carries a grudge, but he is also perfectly and completely correct in pointing out compliance is simply colonialism

      • Moonman45

        excellent viewpoint! the hubris and folly of the primarchs shaped the 40k galaxy as a whole.

  • beau malnack

    If I recall, the Warlords in the mountains were psykers that used their power to rule (hence daemonic summon, undead, and the ability to survive the toxic fog). Typhus (born Calas Typhon) is a descendant of the warlords, which is why he is a psyker. DG used to shun psykers though so he had been told by Mortarion to bury his powers.

    I think Mortarion turned traitor not just because he did not much care for the Emperor, or the leniency of the Edict of Nikea, but also because he disagreed with being ruled over by the bureaucracy of Terra. It is kind of funny and hypocritical how he saved Barbaros from tyrannical rulers just to become one himself.

  • Kenneth Portner

    Where did the baby Mortarion come from? How is it tha he crashed landed landed on Barbarus to be discovered by the Warlord?

    • beau malnack

      Common knowledge all Primarchs were grown in a lab by the Emperor in his Himalayan fortress when chaos warp opened and sucked them all up spitting them on random planets around the galaxy.

  • Tomoyuki Tanaka

    If I recall, all the former home planets of the Traitor Legions were destroyed by Exterminatus after they fled to the Eye of Terror. Just like poor Prospero.