Nemeroth led his Chaos warband in an attempt to conquer the Imperial Forge World of Graia located in the Segmentum Tempestus. Graia was devoted solely to the mass production of military ordnance, weapons and vehicles for the armies of the Imperium of Man. This planet was also notable for manufacturing Warlord-class Titans -- massive and extremely formidable bipedal combat walkers that served as potent weapons of the Adeptus Mechanicus' Titan Legions. Graia was invaded by a large Ork WAAAGH! composed of over 1 million Orks led by the Warboss Grimskull in the late 41st Millennium. Instead of risking an escalating and devastating war with weapons of mass destruction that could seriously damage Graia's much needed industrial output or waiting for the eventual Imperial Guard reinforcements, th