Bolo offensive systems
From the Mark III onwards, the standard Bolo design was intended to provide a consolidated set of capabilities intended to address virtually any combat situation, from operating underwater to engaging enemy units in land, sea, air and even space - the Mark XV/R was able to engage starships in low to medium orbit. Depending on the era and enemy capabilities, a single Bolo was often considered the equivalent of a manned armoured assault brigade or even a full army corps. While each Mark generally opted for a "balanced" approach to offensive and defensive capabilities, there were often specialised variations on the base model, such as heavy siege units, scout units and ECM platforms.
Prior to the Mark XIV, early Bolo Marks utilised projectile weapons for their main battery: a tank gun firing discarding sabot fin-stabilized long rod penetrator shells or a railgun. As the energy-storage capabilities of successive Bolo designs grew, these projectile weapons were replaced, initially by laser cannons, though these were quickly succeeded by the Hellbore: a plasma cannon derived from a battlecruiser's main battery.
Hellbore ammunition consists of slivers of highly-pressurized frozen deuterium which, when fired, are ignited (by a laser) in a fusion reaction. The resulting bolt is contained and directed using strong magnetic fields in the breech and barrel. The resulting plasma travels at a considerable fraction of light speed and is not affected by planetary gravity. However, since the Hellbore was designed as naval armament for Concordiat warships, modifications had to be made to avoid losing a significant portion of the shot's energy to atmospheric attenuation. To this end, a fraction of a second prior to deuterium detonation, a laser is fired along the path of the bolt to create a momentary vacuum. Later Bolo marks are capable of internally manufacturing Hellbore rounds, using water as a raw material, whereby the deuterium isotope of hydrogen is separated and cooled cryogenically into splinters of frozen hydrogen.
The Hellbore first saw service with the Mark XIV and is generally mounted on a turret to provide maximum targeting capabilities. Some Marks experimented with the use of two lighter Hellbores in place of a single, larger cannon; later, heavier Marks generally mount several smaller "support" Hellbores in addition to the main battery. Hellbore power output is measured in megatons per second; the diameter of the tube is a more common quantifying measure. The Mark XIV mounted a single 25 cm Hellbore; the Mark XXXIII featured three 200 cm and sixteen 30 cm Hellbores. The Mark XXXIV carries a variant of the Hellbore known as the Hellrail, an anti-starship railgun weapon, possessing an output of 90 megatons per shot. Hellrails are designed for planetary defense and cannot normally be depressed to strike ground targets.
All Marks of Bolos are equipped with a set of secondary batteries, generally known as infinite repeaters. Depending on the era and Mark, this term covers the use of Gatling guns, anti-personnel flechette launchers, small-bore railguns, energy weapons and even small-caliber Hellbores. Other secondary armaments include indirect weaponry such as rapid-fire mortars, heavy howitzers, and surface-to-surface/surface-to-air missiles. Bolos can be equipped with thermonuclear weaponry, though the use of these on inhabited planets is generally restricted.
Mark XXXIIIs are known to carry Dragon hover-tanks and Wyvern flyers in combat to provide additional offensive and scouting capabilities. Many Marks also carry maintenance drones which can be deployed externally if required.