Olympia

Olympia was the original homeworld of the Primarch Perturabo and his Iron Warriors Traitor Legion before they turned to Chaos during the Horus Heresy. Olympia was an Imperial Civilised World before it was destroyed following the Heresy by the Imperium because of its irrevocable Chaotic taint.

Climate and Geography
Ten thousand standard years ago, Olympia was a rugged and mountainous world with most of the planet's population centered in giant city-states. The plentiful quantities of quarried stone and the mountainous terrain of the planet made siege warfare endemic on Olympia, hence the Primarch Perturabo's extraordinary skill at assaulting heavily fortified positions, a specialty he passed on to his Space Marine Legion once he was placed in command of the Iron Warriors.

Perturabo
The young Perturabo was discovered climbing the sheer cliffs below the city state of Lochos. Aware that this was no ordinary child, the city guard brought him before the Tyrant of Lochos, Dammekos. Intrigued by the strange, dark child, Dammekos took him into his household as if he were his own family. Perturabo never trusted the Olympians and, although Dammekos took time and troubte to win the trust and affection of the boy, Perturabo did not respond with any warmth. Many saw him as a cold youth but when one considers that he had been cast alone into a strange world with no clue as to his own origins or the reason. for his unusual abilities, this is perhaps harsh

The Great Crusade
When the Emperor's Great Crusade reached Olympia, Perturabo pledged his loyalty to the Еmperor and, as was his custom with his Primarchs the Emperor granted Perturabo command of a Space Мarine Legion and certainty of the planet as the Legion's home. The deposed Tyrant of Lochos spent the last few years of his life trying to marshal support to reclaim Olympia. He failed, but created an undercurrent of unrest that was to be harnessed many years later.

There was little time to delay. With the Great Crusade in full swing, Perturabo recruited new Iron Warriors from amongst the Olympians and conducted a lightning campaign against the nearby world of Justice Rock and the heretical Black Judges. The new recruits served well and their triumphant return was celebrated in the Palimodes Fresco, now known only through fragmented holo-recordings.

Rebellion
In the midst of the cleansing of the Hrud Warrens on Gugann matters were brought to a head. It was Horus who broke the news to Perturabo that Olympia was in rebellion. Dammekos had died and the population, incited by demagogues, had taken up arms. Perturabo was by this time tired of repeatedly having to prove his worth and now, after all his battles, the thought of being the only Legion unable to hold its own home world appalled him. Horus made the most of the opportunity. Through Horus' gift of the hammer Forgebreaker, an unspoken pact was signed between the two and Perturabo left with his Iron Warriors to quell this rebellion. Although it may have been possible that the weapon acted as a conduit through which the forces of Chaos could manipulate the Iron Warriors Primarch.

The Massacre of Olympia
Perturabo and the Iron Warriors suppressed the rebellion on the streets of one city state after another. No one was spared. It was the principle of surrender or no quarter, and the Iron Warriors had grown accustomed to granting no quarter. Perturabo watched on as unmoved and cold as the fortifications in which he taken such pride were overcome. By the time the massacre was over, Olympia had been culled into slavery with almost 5 million civilians dead.

As the pyres burned through the long Olympian night, the Iron Warriors slowly realised the extent of what they had done. One moment they were humanity's heroes assaulting the Hrud and the next they were committing genocide. Perturabo was like a man emerging from a drunken stupor who finds blood on his hands, only dimly aware of how it got there, but is aware of an oppressive feeling of shame nonetheless. He knew that the Emperor could never forgive him his crime.

Horus Heresy
It was in this doomed mood that the Iron Warriors received news and orders. The news would have been shattering under normal circumstances, but when heard in ruins that were thick with the stench of the dead, it was apocalyptic. Russ' Space Wolves had attacked Magnus' Thousand Sons on Prospero. Horus had turned renegade along with his own Sons of Horus. Angron's World Eaters and Mortarion's Death Guard were also with him. Fulgrim and the Emperor's Children had tried to reason with Horus, but had been seduced into joining him instead. Now the universe exceeded the Iron Warriors in madness. Confused bewilderment gave way to the realisation that, with the entire Imperium in flames, their excesses were irrelevant.

According to the accompanying orders they had received, the Iron Warriors were to join six other Legions to face Horus on Istvaan V - the events which occurred there becoming a part of the Horus Heresy legend. The Iron Warriors joined with the Night Lords, Word Bearers and Alpha Legion and helped carry out the massacre of the three Legions in the task force who remained loyal.

A strong contingent of the Legion accompanied Perturabo to Terra where he supervised the siege of the Emperor's Palace. Here his skills were invaluable and the Iron Warriors found a sublime pleasure in tearing the edifices of the Imperium down. The end was near for the defenders when the Emperor confronted Horus on his battle barge and defeated him. Like many of Horus' followers, the Iron Warriors fled to the Eye of Terror, securing a new home world where they could brood on the turn of events and plot vengeance.

Post-Heresy
The rest of the Iron Warriors defended their small empire based on Olympia, but there was no refuge from the retribution of the Loyalist Legions. The Imperial Fists supported the Ultramarines in a decade-long campaign to liberate the subjugated worlds. They discovered the Iron Warriors to be like a barbed hook that, once embedded into a victim, could only be removed with great risk of injuring the patient further. The Olympia garrison held out for two years, eventually triggering their missile stockpiles when defeat was unavoidable. They left a blasted wasteland that, like the other Traitor Legion home worlds, was declared Perdita.

After having taken part in the Horus Heresy, the Iron Warriors retreated into the Eye of Terror with the other Traitor Legions and took a world for themselves called Medrengard. Nothing is known for certain what this world truly looks like, as the realm of Chaos is constantly shifting. Reports of Inquisitor Maul describes it as a world that is one great fortress, the entire world transformed into a tremendous fortified position with impossibly high towers and Chaos warships hovering everywhere above it.