Chemos was once the homeworld of the Emperor's Children Traitor Legion before their corruption by the Chaos God Slaanesh and betrayal of the Emperor of Mankind during the Horus Heresy. Chemos was the planet where the Emperor's Children's Primarch Fulgrim was discovered by the Emperor during the Great Crusade.

In ancient days Chemos was classified as a Mining World. By the time of the later Great Crusade it was classified as a Civilised World, but following its scouring after the Horus Heresy by the Loyalist forces of the Imperium, it is now a Dead World, wiped clean of all life.


The world of Chemos in the Ultima Segmentum's Aquitane Sector was originally settled by human colonists before the Age of Strife, when Warp travel became impossible due to the numerous Warp Storms that cut off the human settled worlds from one another, forcing these isolated worlds to fend for themselves without the support of their human-settled neighbours in other star systems. An ancient surviving text from that time, known as the Libram ex Dominar, tells that Chemos was one such world, a industrious mining colony dependent on interstellar trade for food. The planet's rulers made every effort to extract enough raw food from the harsh environment to feed their people, but Chemos was a world dying a slow death.

During its isolation, the archivists of Chemos recorded a picture of a bleak, unforgiving world. Warmed by two small, distant suns and surrounded by a nebular dust cloud, it experienced neither day nor night, only a perpetual grey twilight in which the stars never shone. Settled long ago as a mining colony, the cities, outposts, mining centres and towns of Chemos had fallen into decay since their isolation from Terra. Without resources from other worlds to sustain the people of Chemos, trade with other worlds ended, thousands starved, cities were abandoned, and eventually it fell down to just a few hardy fortress-factories to keep humanity alive on Chemos.

Short of food, water and energy, the people of Chemos were forced to limit themselves to the meagre supplies available, all citizens worked every waking hour, operating the vapour mines that drew moisture from the thin air, and the huge synthesisers that endlessly recycled food, turning yesterday's waste into today's sustenance. When not working, the inhabitants of the factory-fortresses would march through the ruins of once-great industrial cities, searching for building materials, technology and the ruins of spaceships to strip of useful parts.

Recreation, art and leisure were sacrificed in order to ensure survival, and efficiency became the only value adhered to. This all changed when one day the guards on the crumbling walls of Callax, the largest remaining factory-fortress, saw a meteor descend from the clouds, trailing fire across the sky before impacting onto the rocky, dusty ground barely a mile from the fortress walls. Though little manpower could be spared, the ruling Executive of Callax sent a handful of scouts to investigate the impact site, hoping for some evidence of human survivors on other worlds. What they found became legend.

Discovery of Fulgrim

Chemos Map

Ancient Departmento Cartographicae Map showing the location of Chemos in the Ultima Segmentum

In the centre of the crater, surrounded by the white-hot remains of a stasis capsule, was a child, barely more than a baby. Orphans were normally put to death on Chemos -- the Executive spared no resources to look after those who were unable to return their investment by working in the factory-fortresses -- but the captain of the Callax scouts looked into the eyes of the child and saw something more than human. In defiance of tradition, the captain of the scouts appealed to the Executive. Because of his value to Callax, the captain was allowed to adopt the infant as his own. He named his adopted son after an old legend long-since discarded by the people of Chemos, the mythical god of creation Fulgrim. The child named after this legend soon created a legend of his own, one that would become known to all the people of his world.

Fulgrim grew unnaturally fast, becoming a strong, capable man. At half the age of his fellow workers he was able to fulfill his obligations to the Executive, working for days without rest. Not only was he physically proficient, he quickly grew to understand the technology of the machines he worked with, and began to contemplate their improvement. By the fifteenth anniversary of his fall from the sky, Fulgrim had risen from the ranks of the workers, first becoming an engineer, then one of the Executives itself. Learning of the slow deterioration in Callax and the other remaining settlements of Chemos, Fulgrim set himself the task of saving his world and changing it from a dying ex-mining planet into the centre of art and wealth it became under Imperial rule.

One by one he convinced his fellow members of the Executive Board to fight against the entropy that was destroying Chemos. Under Fulgrim's leadership, teams of engineers travelled far from the factory-fortresses, reclaiming and repopulating long-dead outposts, mining centres and fortresses in the planet's most inaccessible regions. The ancient mines were reopened and expanded, bringing more and more minerals into Callax and allowing the construction of more sophisticated machines.

Recycling efficiency grew until, at last, Callax was producing more that it consumed. Seeing his people prosper, Fulgrim took pride in fostering the re-emergence of art and culture, reclaiming the spirit of humanity that had been sacrificed so long ago in the struggle for survival. Terraforming technology was reinvented, allowing forests, oceans, plains and rainforests to spread from the reclaimed outposts and bring life to the planet. As Callax grew, the other settlements began to ally themselves with Fulgrim and helped him rebuild and repopulate the long-abandoned cities of the planet. Using building materials mined out of the reopened mines, ancient buildings were patched up and reconstructed even as towers and skyscrapers rose over the ground. Fifty standard years after Fulgrim fell from the sky, he rose to sole rulership of Chemos.

As beautiful forests were planted on ground once mined for metals and wondrous cities of glass, gold, crystal and steel rose to new heights of glory, Fulgrim's presence drove a resurgence of craft, art and intellectual refinement, and through dint of his intellect and achievements he halted the backsliding of this hardscrabble world and set it upon a path, if not to greatness, then at least to a betterment of its lot. Metropolises built over rocky plains and forests grown on stony ground, this impulse to strive for something better would allow the people of Chemos to attain something akin to great heights, and the changing of Chemos into a world of art and culture inspired Fulgrim the will to grasp even more greatness.

It was not long after this that the planet's isolation came to an end. From the blue sky came a flight of dropships, armoured and battle-scarred, each bearing the same symbol, a two-headed eagle. On hearing of this, some fragment of memory stirred in Fulgrim. Chemos had no formal army, but the dropships' landing zone had been surrounded by the Caretakers, the police-soldiers once responsible for maintaining order in the factory-fortresses. Fulgrim sent word to the Caretakers to stand down and allow the visitors from above into Callax.

Arrival of the Emperor

In his spartan quarters in a tower at the heart of the greatest city on the planet, Fulgrim was faced by armoured warriors from the stars. Their faces bore the scars of many battles, and from their shoulders hung scrolls listing their achievements. Their armour and weapons were finely-worked, and their banners and pennants were works of art. Fulgrim recognised that these men were not merely more advanced than the people of Chemos, but truly civilised -- his lost brothers from the stars had preserved the arts he had longed to return to Chemos. From the midst of these warriors stepped their leader, the Emperor of Humanity. Fulgrim surveyed him and, without a word, knelt and offered his sword. On that day Fulgrim swore to serve the Imperium with all his heart.

From the Emperor Himself, Fulgrim learned of Terra, of the Great Crusade to reclaim the galaxy, and of his own origins. Though the story was fantastical in nature, he knew it to be true, and at the Emperor's request Fulgrim travelled to Terra to join the Space Marine Legion that had been created from his genetic material.

Unlike the other Legions fighting in the Crusade, the Astartes of the IIIrd Legion were few in number -- an accident had destroyed nearly all of the Legion's precious gene-seed during transit from Luna to Terra and the reserves had been corrupted by a terrible infection.

With the Primarch himself lost, the rebuilding of the Legion's gene-seed had proven to be a slow and difficult process. Fulgrim addressed the two hundred warriors who were then all that the IIIrd Legion could muster. There were so few that each of them bore a banner of a company of the Legion that had either perished, or now numbered only a handful of warriors.

Yet they were unbowed and stood with pride, as if in defiance of fate. The Primarch may have seen an echo of the struggle of Chemos in his remaining gene-sons. To them he gave the sacred task of bringing the Emperor's wisdom to all the stars in the sky, "You are the Emperor's chosen, his heralds, his warriors, his children, for this is only the beginning," the Book of Primarchs relates he told them upon their first meeting.

On hearing of Fulgrim's words, the Emperor renamed the IIIrd Legion the "Emperor's Children," ratifying a name long known within the Legion since their defence of the Master of Mankind during the Proximan Betrayal early in the Great Crusade but now given the full legal force of Imperial decree. The Officio Militaris' College of Arms recorded the change and marked the III Legion's panoply as imperial purple with the talon-spur as their emblem and the unique right to bear the Aquila Palatine as executors of the Imperial will, an honour given to the Emperor's Children alone among the Space Marines until after the betrayal of the Horus Heresy.

Fulgrim was anxious to begin his conquest of the unknown regions of the galaxy as part of the ongoing Great Crusade, but realised that his two hundred warriors were far too few to undertake the Crusade on their own. With the Emperor's blessing Fulgrim and his IIIrd Legion joined the Luna Wolves on campaign, and Fulgrim fought side-by-side with his brother Primarch Horus, aiding him in his newly-assigned task of pacifying the Eastern Fringe of the galaxy. The Warmaster himself soon praised Fulgrim and his Legion, declaring them the living embodiment of the everything the Legiones Astartes aspired to be.

Great Crusade

Swelled by new recruits drawn from Chemos and Terra, the Emperor's Children finally mustered the strength to undertake a portion of the Crusade alone, and Fulgrim proudly led his warriors into the unknown. To countless worlds he brought the rule of the Emperor, crushing any resistance in the certain knowledge that any who fought against the Emperor fought against humanity itself. From the growing ranks of his Legion, Fulgrim selected a few individuals, the bravest, strongest and noblest, to bear the rank of Lord Commander, each given charge of a full battle company.

Fulgrim taught the Lord Commanders personally, taking care that they were worthy of the honour of being the representatives of the Emperor. In turn the Lord Commanders passed Fulgrim's words on to the officers under their command, and they to their squads. In this way, through their leaders, each Space Marine of the Emperor's Children Legion followed the Emperor himself.

To honour the Emperor, they strove for perfection in all things: battlefield doctrine was obeyed to the letter, tactics and strategy were studied in minute detail and perfected, and the Emperor's decrees were memorised by every Space Marine, adhered to in every way. While the Emperor's Children, like many Legions, considered the Emperor a man, not a god, their reverence and adoration for him bordered on the fanatical.

After coming under the rule of Fulgrim and its rediscovery by Imperial forces, Chemos quickly expanded its industrial base tо become both an important source of processed minerals and, more importantly, a centre of Imperial culture, art and high society. No longer would a traveler from another world see crumbling factory-fortresses, now they would see a paradise planet of beautiful forests, shining, wealthy cities, marble palaces and monuments of marble and diamond.

"Beautiful Clemos", as it was known, provided the majority of the early Imperium's scholars, actors, merchants and great beauties. The grand fortress-monastery of the Emperor's Children was established on the magnificent forested hills near Callax (now having grown into a shining city of art, pleasure and commerce that bore no resemblance to the factory-fortress of old), drawing recruits from the strongest, bravest and most intelligent of the planet's population.

Though Fulgrim himself never returned to Chemos, he took great care to see that his will, as the emissary of the Emperor, was followed. The recruits for the III Legion from Chemos proved themselves strong and resourceful warriors, but even so only a handful of them passed the rigorous tests imposed by Fulgrim to satisfy himself that they were worthy of becoming one of the Emperor's Children.


After the lifting of the Siege of Terra, and the end of the Horus Heresy, Imperial forces set out to assault Chemos from orbit, intending to destroy the Emperor's Children's fortress-monastery outside Callax. They bombarded all the other fortress cities and palaces from orbit into nonexistence and eradicated any trace of Chaos from the world.

During Chemos' final hours, the work known as the Chemosian Cantos was first penned. It was later revered as a sacred scripture by the human slaves and Chaos Cultists who served the Emperor's Children Legion and worshiped Slaanesh.

Following this action Chemos was quarantined by the Inquisition, and in the past ten millennia no further information, not even a record of Exterminatus, has appeared in Imperial databases regarding the world, though the orbital bombardment rendered the once beautiful and wealthy world lifeless.


  • Index Astartes I, "Children of the Emperor - The Emperor's Children Space Marine Legion"
  • The Horus Heresy - Book One: Betrayal (Forge World Series) by Alan Bligh, pp. 104-105, 191, 290-291
  • Fulgrim (Novel) by Graham McNeill, Ch. 12
  • Fabius Bile: Primogenitor (Novel) by Josh Reynolds, Ch. 2
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