===Horus Heresy===

====Rebellion====

Shortly after the [[Sak'trada Deeps Campaign]] Perturabo learned that his homeworld, Olympia, was in rebellion. Dammekos was dead and in his absence the politicking and bickering of the city-states had resumed. Perturabo demanded the Olympians themselves enact decimation, killing one in every ten of their own or face extermination and enslavement. Many refused, and Perturabo purged Olympia city by city, overrunning the fortresses he had built and sparing no one. Iron Warriors that refused to take part in the genocide suffered the same fate.{{Fn|12c}} By the time the massacre was over, five million Olympians had been killed and the rest put into [[slavery]]. While storming [[Lochos]]' palace, Perturabo came across his old foster sister [[Calliphone]] and strangled her to death after a furious argument where she blamed the Primarch for what had befallen their world. As Olympia died, Perturabo looked on in cold silence. After the pyres were burning, the Iron Warriors realized what they had done. They were no more the saviours of the [[Imperium]] - they had been destroying the Hrud one moment and the next they were committing genocide on their own. Perturabo realized the Emperor could never forgive him for what he had done.{{Fn|12d}} Horus, on the other hand, commended Perturabo for his decisive action and the Lord of Iron swore an oath of loyalty to the [[Warmaster]]. After the [[Dropsite Massacre]], Horus would present Perturabo with a hammer named [[Forgebreaker]], the gift symbolic of a signing of a pact between them. {{Fn|7b}}