Endymion Prime is a blighted Industrial World located in the Endymion Cluster within the Maelstrom Zone of the Segmentum Ultima. During the Badab War the brutal and savage Carcharodons Chapter of Space Marines were unleashed upon the worlds of the Endymion Cluster in order to defeat the Secessionist Mantis Warriors Chapter and protect the flank of the Loyalists as they launched a full invasion of the Badab Sector. The Carcharodons systematically annihilated planets in the Cluster known to have harboured the Mantis Warriors and forced the Secessionist Chapter to stop using their hit-and-run tactics and concentrate their forces in defence of these worlds. This strategy spared the Carcharodons from having to pursue the Mantis Warriors across the Cluster to worlds where their foes held the adv