The Great Scouring, or simply The Scouring, was the Imperium of Man's great counter-offensive against the Traitor Legions. It began immediately after the end of the Horus Heresy following the death of the Warmaster Horus and the failure of his Siege of the Imperial Palace during the Battle of Terra in the early decades of the 31st Millennium. It succeeded in driving the Forces of Chaos from Imperial space into a permanent refuge in the Warp rift known as the Eye of Terror.