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At a glance
Cthonia was a hive world close to Terra, so thoroughly mined over the millennia that its crust was riddled with tunnels and shafts and its interior hollowed into a labyrinth. Its surface was a polluted wasteland of slag heaps and abandoned workings, and its people lived in a brutal society of gangs, feuds and constant violence. It was on Cthonia that the infant Primarch Horus Lupercal was found, and it became the recruiting ground of his Legion, the Luna Wolves, later renamed the Sons of Horus.
The gangs of Cthonia produced warriors who were cunning, tough and ruthless, ideal material for a Space Marine Legion. Their culture of loyalty to one's gang, of oaths sworn in blood and of contempt for weakness shaped the character of Horus's Legion, and through it the Black Legion that rose from its ashes. Abaddon the Despoiler, the most feared enemy of the Imperium, was born on Cthonia.
After the Horus Heresy, Cthonia faded from Imperial records. Its fate is uncertain. Some accounts say it was destroyed, others that it was simply abandoned as worthless, its tunnels left to collapse. To the Black Legion, it remains a memory of the world that made them, and the habits of its gangs still echo in their warbands.
Geography & environment
Cthonia was a world exhausted by mining. For thousands of years, its crust had been dug for minerals and metals, and its interior was riddled with tunnels, shafts and caverns. The surface was a wasteland of slag heaps, spoil tips and abandoned mine workings, and the air was thick with dust and pollution. The planet's resources were largely depleted, and its industries were in decline.
Most of Cthonia's population lived underground, in the tunnels and caverns left by the mines. These underground cities were dark, cramped and dangerous, with collapses, floods and gas pockets constant threats. The tunnels stretched for thousands of kilometres, and many were unmapped. Gangs controlled different territories, and travel between them was dangerous.
The deepest tunnels were said to reach far into the planet's mantle, and some Cthonians believed that the planet was hollow. Legends told of monsters in the depths and of lost civilisations buried beneath the rock. These stories were probably exaggerations, but the depths of Cthonia were certainly dangerous, and few who ventured into them returned.
The tunnel cities
Life in Cthonia's tunnels was hard. Food and water were scarce, and the gangs fought over every resource. The tunnels were lit by flickering lamps and the glow of furnaces, and the air was hot and stale. The people of Cthonia lived in crowded, makeshift dwellings, carved into the rock or built from scrap. Disease was common, and life expectancy was short.
The gangs were the dominant power in the tunnels. Each gang controlled a territory, from a single tunnel to a vast network of caverns, and they fought constantly with their rivals. Gang wars could last for years, and they were often fought with knives, clubs and crude firearms. The gangs were organised around strong leaders, and loyalty to the gang was paramount. Members marked their allegiance with tattoos and scars, and betrayal was punished by death.
Some tunnels were home to more organised communities, which maintained the mines and factories that still operated. These communities were under constant threat from the gangs, and they paid tribute for protection. The tunnels were also home to scavengers, outcasts and mutants, who lived in the abandoned areas and preyed on travellers.
History
The finding of Horus
According to legend, the infant Horus arrived on Cthonia during the scattering of the Primarchs. He was found by the people of the tunnels and grew up among the gangs, where he learned to fight and to lead. By the time the Emperor arrived, Horus was already a warrior and a leader of men. Horus was the first of the Primarchs to be found, and he became the Emperor's favourite son. He spent many years fighting at the Emperor's side before he took command of his own Legion.
The Luna Wolves
Horus's Legion was the XVI Legion, the Luna Wolves. Under Horus, the Legion recruited heavily from Cthonia, and its warriors brought the habits of the gangs with them. The Luna Wolves were known for their aggression, their skill in close combat and their tight bonds of brotherhood. Their warriors swore oaths to each other and to their Primarch, and they regarded loyalty as the highest virtue.
During the Great Crusade, the Luna Wolves became one of the most successful Legions. Horus was appointed Warmaster after the Scouring of Ullanor, and his Legion was renamed the Sons of Horus in his honour. Its four greatest captains formed the Mournival, an inner council that advised Horus. Abaddon, the First Captain, was one of them.
The Heresy and after
When Horus fell to Chaos, his Legion followed him. The Sons of Horus led the rebellion against the Emperor, and they fought at the heart of the Heresy, from Isstvan to the Siege of Terra. When Horus was slain by the Emperor, the Legion fled into the Eye of Terror. There it was shattered by its rivals, and Horus's body was stolen and later burned by Abaddon. Abaddon then renamed the survivors the Black Legion, and he has led them in Black Crusades against the Imperium ever since.
The fate of Cthonia itself is uncertain. After the Heresy, the Imperium may have purged it in retribution for its connection to Horus, or it may simply have been abandoned. Whatever happened, it disappeared from Imperial records, and its name was largely forgotten.
Gang culture and the Legion
The culture of Cthonia's gangs left a deep mark on the Luna Wolves and the Sons of Horus. Many Legionaries wore tattoos and scars that marked their origins, and they continued the gangs' tradition of swearing oaths. Their speech was laced with Cthonian slang, and they valued strength, cunning and loyalty to one's brothers above all.
The Sons of Horus also inherited the gangs' contempt for weakness. They were ruthless with their enemies and harsh with their own. Disputes between warriors were often settled with fists or blades, and the strong rose while the weak fell behind. Their culture was one of competition as well as brotherhood, and their captains vied for Horus's favour.
The Cthonian tradition of oaths may also have made the Legion vulnerable to corruption. Before the Heresy, secret lodges spread among the Legions, where warriors swore oaths of secrecy and brotherhood. The Sons of Horus embraced the lodges, and through them, the corruption of Chaos spread. When Horus fell, his warriors were already bound to him by oaths that went deeper than their loyalty to the Emperor.
Abaddon, son of Cthonia
Of all the warriors Cthonia gave to the Imperium, none became more infamous than Ezekyle Abaddon. Born in the tunnel cities, he rose through the ranks of the Luna Wolves to become First Captain, commander of the Justaerin, the Legion's elite Terminator company. He was utterly devoted to Horus, and many said he resembled his Primarch so closely that he could have been his son by blood. That devotion defined his life, and it made his later disillusionment all the more bitter.
When Horus fell, Abaddon followed him without hesitation. He fought at the Siege of Terra and he was aboard the Warmaster's flagship, the Vengeful Spirit, when Horus was slain by the Emperor. In the aftermath, Abaddon came to believe that Horus had failed because he had become a slave to the Dark Gods rather than their master. He resolved never to make the same mistake. He would use the powers of Chaos, but he would serve no god.
From the shattered remnants of the Sons of Horus and other broken warbands, Abaddon forged the Black Legion, and in M41 he finally broke the Cadian Gate in the Fall of Cadia. The ruthlessness he learned in the tunnels of his youth has never left him. He leads by strength and fear, as the gang bosses of Cthonia once did, and those who fail him rarely live to fail again.
The Mournival and the lodges
The Mournival was a tradition unique to the Luna Wolves. Its four members, two senior and two junior captains, served as Horus's closest advisers, and they were expected to speak openly to him, even when he did not want to hear what they had to say. The name came from a Cthonian card game, and the council's symbol was the phases of the moon. In its time, the Mournival included Abaddon, Horus Aximand, Tarik Torgaddon and Garviel Loken.
The Mournival reflected Cthonian values of honesty among brothers and loyalty to the gang. But it could not protect the Legion from corruption. When the warrior lodges spread through the Legion, the Mournival split. Abaddon and Aximand embraced the lodges and followed Horus into rebellion, while Torgaddon and Loken remained loyal. At Isstvan III, Torgaddon was killed by Aximand, and Loken was left for dead. The brotherhood that had defined the Legion was broken, and from its ruins came the Black Legion.
People & culture
The people of Cthonia were tough, cynical and violent. They lived in a world where survival depended on strength and cunning, and they had little patience for weakness. They were fiercely loyal to their gangs and their families, and they regarded outsiders with suspicion. They had a dark sense of humour and a love of storytelling, and they celebrated the deeds of their heroes.
Cthonian culture was steeped in violence. Children learned to fight at an early age, and they joined gangs as soon as they could. Gang members marked themselves with tattoos and scars, which told the story of their lives and their allegiances. Violence was a way of life, and death was a constant companion. Yet the people of Cthonia also had a strong sense of community, and they would fight to the death to protect their own.
The Legion recruited aggressively from among the gangs. Cthonian youths who had proven themselves in gang wars were highly valued, and many sought to join. Those who were chosen left their gangs and their families behind, but they took their culture with them.
The legacy of Cthonia
Cthonia is gone from the Imperium's maps, but its legacy endures in the warbands of the Black Legion. Its warriors still mark themselves with tattoos and trophies, and they still swear oaths to their leaders and to each other. Their tactics of ambush, boarding and close-quarters killing were learned in the tunnels of a world that no longer exists. Their contempt for weakness and their hunger for power are the values of the gangs, carried across ten thousand years.
To the Imperium, Cthonia is a warning. It shows how a world's culture can shape a Legion, and how a Legion can carry that culture into damnation. The Inquisition has long been wary of worlds that produce warriors as hard and as ruthless as Cthonia's. Some scholars have suggested that the Emperor chose Cthonia as a recruiting world precisely because its people were so tough, and that he paid the price for it when his favourite son turned against him.
For the Black Legion, Cthonia is a memory of what they once were. The oldest among them, those who were born there ten thousand years ago, remember the tunnels and the gangs. They remember the oaths they swore and the brothers they lost. And they remember the day they left Cthonia to join the Luna Wolves, believing they would conquer the galaxy in the Emperor's name.
Defenders & war-machine
Cthonia was never a fortress world. Its gangs and its tunnel communities were defended by their own warriors, armed with whatever they could find. The Imperium maintained a presence on the planet to manage its mines and to recruit for the Legion, but it was never heavily garrisoned. The tunnels themselves were its greatest defence: a maze where any invader could be ambushed and lost.
The Cthonian gangs fought with knives, clubs, crude firearms and explosives. Their tactics were based on ambush and close combat, suited to the cramped tunnels. The Luna Wolves adopted many of these tactics, and they became masters of boarding actions and close-quarters fighting. The tradition lives on in units such as the Cthonian Beserks, who fight with the savagery of the old tunnel gangs.
Notable battles
- The gang wars of Cthonia: endless feuds between the tunnel gangs, which shaped the warriors who would become the Luna Wolves.
- The Scouring of Ullanor (M30): Horus wins his greatest victory and is named Warmaster; see Scouring of Ullanor.
- The Siege of Terra (M31): the Sons of Horus lead the assault on the Imperial Palace; see Siege of Terra.
Trivia
- Horus was the first of the Primarchs to be found by the Emperor.
- The Mournival was the inner council of the Sons of Horus, made up of four captains.
- Abaddon was born on Cthonia and became the First Captain of the Luna Wolves.
- The Black Legion still carries traditions that can be traced back to Cthonia's gangs.
- The name of the Mournival came from a Cthonian card game, and its emblem showed the phases of the moon.
- Garviel Loken, the loyalist member of the Mournival, survived Isstvan III and later served Malcador the Sigillite as one of his Knights-Errant.
