The Chapter quickly established a bloody reputation for itself as it engaged in a campaign of systematic annihilation of the worlds of the Endymion Cluster, whose inhabitants still owed some loyalty to the Mantis Warriors. Planet after planet was placed under a scorched world policy, their infrastructure smashed and countless multitudes slain, which forced the hand of the Mantis Warriors, whose honor would not allow them to stand by and see people suffer. This played into the plans of the Carcharodons quite nicely, and soon all resistance from the Mantis Warriors was crushed, their days as an effective fighting force over.

With the reign of the Tyrant of Badab at its end, the Carcharodons would return one final time to the Endymion Cluster, and aided the Fire Angels in bringing back the worlds there into compliance. With the blessings of the Fire Angels, whose dominion the Cluster had been granted at the cessation of hostilities, the Chapter visited the Tranquility system. There their dark legend would be sealed. The hidden fortresses of the Mantis Warriors were ransacked of supplies and war materiel, and a whole generation of the system's young men were taken away to replace the losses the Chapter had incurred during the war, forced to fight each other to the death to see who would be worthy to join the Carcharodons' ranks.