The Legion Wars, known also as the Slave Wars, or sometimes referred to as the Eye of Terror Slave Wars, were waged shortly after the end of the Horus Heresy in the Eye of Terror between the various Traitor Legions of Chaos Space Marines in the early 31st Millennium. This conflict marked the final collapse of unity between the Chaos-corrupted Space Marine Legions that had fought unified under the banner of Horus Lupercal during the Horus Heresy. It also marked the transformation of the Sons of Horus into the Black Legion led by Horus' ultimate successor, Abaddon the Despoiler. Many of the events of this conflict remain unclear or distorted to Imperial chroniclers due to the difficulty of gaining information about the actions of the Traitor Legions within a Warp rift like the Eye of Terror.