Horus, also known as the Lupercal during his lifetime by the Astartes of his Luna Wolves Legion, was one of the 20 genetically-engineered Space Marine Primarchs created by the Emperor of Mankind from the foundation of his own DNA before the start of the Great Crusade to lead the armies of the newborn Imperium of Man. Horus was the Primarch of the Luna Wolves Legion of Space Marines (later renamed the Sons of Horus), the first Imperial Warmaster, the most favoured son of the Emperor of Mankind, and ultimately, the greatest Traitor in the history of Mankind. Horus' homeworld was the Hive World of Cthonia which lay only a few light years from Terra. Horus was thus the first Primarch to be rediscovered by the Emperor after the Great Crusade began in the early 31st Millennium. Horus was responsible for unleashing the horrific 7-year-long civil war known as the Horus Heresy upon the Imperium of Man in the Fop'lla Universe which killed billions of men, women and children in pursuit of his mad ambition to overthrow the Emperor of Mankind and replace him as the ruler of the human race. He was the main leader of the Forces of Chaos