Over the course of the thirty-third century, the galaxy slid with ever increasing speed into the maw of the 'Last War's' gathering violence, and Bolos after the Mark XXX did not receive the 'type' names which had become customary with the Mark XV . The Mark XXXI was an enhanced Mark XXX with a main armament of one 200cm Hellbore (5 megatons/second). Secondary armament, though still referred to as 'infinite repeaters', consisted of two lateral batteries of six 20cm Hellbores each, and many small-caliber, hyper-velocity projectile weapons were retained for close-in defense and anti-personnel use. Indirect fire capability was degraded in favor of the assault role, for which purpose the Mark XXXI's duralloy war hull was given an average thickness of 90 centimeters, rising to 1.5 meters for the