Bolo!

A Brief Design History of the Bolo

MARK I BOLO (2000):

The Mark I Bolo was an early twenty-first century update of current Abrams technology armed with a single turreted main gun (150mm; 1,722 mps muzzle velocity) capable of defeating any existing vehicle’s armor (including its own) firing DSFSLRP (discarding sabot, fin-stabilized, long-rod penetrator) rounds. The Mark I carried secondary-turreted point defense/anti-personnel gatlings with on-mount radar and computerized fire control packages, required a conventional four-man crew, and relied upon a pair of high-efficiency, fossil-fueled turbines for power. Combat radius was 1,000 kilometers with a battle weight of 150 metric tons. Maximum speed was approximately 80 kph (road). The Mark I was replaced in production fairly quickly by the Mark II under the pressure the new arms race exerted on R amp;D as the traditional world order slipped towards general collapse.

MARK II BOLO (2015):

The Mark II was an updated Mark I, with greatly improved onboard computers and the same main armament, but with the first light lateral infinite repeater armament (four railguns in two two-gun batteries). Fitted with gatling and counter-missile point defense. First durachrome armor (10 millimeter) capable of defeating any weapon short of the Bolo’s own DSFSLRP round. Electronics were designed to allow a single crewman to assimilate data and operate the entire system, and weight rose to 194 metric tons. The Mark II’s fossil fuel power plant drove electric generators rather than powering its drive train directly, and the vehicle had a limited (12-hour) backup power supply of ionic batteries. The Mark II could also operate on electrical power from a secondary source (such as local civilian generator capacity) to maintain long-term readiness in the area defense role. Maximum speed was approximately 80 kph (road) to 30 kph (cross-country in average terrain). The Mark II was the last Bolo with only two tread systems; all later marks were designed with “wide track” treads-that is, with multiple track systems across the full width of the vehicle to reduce ground pressure to the lowest possible value.

MARK III BOLO (2018):

A near contemporary of Mark II, the Mark III was actually designed as a “heavy” (300 metric tons) companion vehicle. The Mark III’s single 150mm main gun (which was not turreted and had only a 20 degree traverse) was backed by an 8-gun infinite repeater battery, a heavy indirect fire support capability (four 155mm howitzers and a light VLS missile system), and an upgraded anti-missile armament. Unlike the Mark II, the Mark III carried only a single fossil-fueled power plant, strictly for backup use; power was normally drawn from heavy banks of ionic batteries, and the Mark III was the first Bolo designed from the outset to use solar film recharging. The vehicle also carried a marginally better sensor suite and a thicker durachrome hull (20 millimeter) which could be pierced at pointblank range (250 meters or less) by a 90 degree hit with the 140mm or 150mm DSFSLRP round; otherwise, it was effectively immune to anything short of a contact nuclear explosion. The Mark III was designed for a two-man crew with the second crewman serving as electronics officer (EW, sensors, etc.), but could be crewed by a single experienced operator in a pinch. The last Pre-Collapse Bolo, it was the first Bolo with multiple tread systems-inner and outer-with an independent power train for the inner pair, but maximum speed fell to 50 kph (road), 25 kph (cross-country).

MARK IV BOLO (2116):

The first Post-Collapse Bolo picked up where the Mark II left off. The Mark IV had a much improved sensor suite and carried a main armament of one 165mm railgun, backed by six infinite repeater railguns (20mm). The Mark IV was the first Bolo to use energy weapons (laser clusters) to supplement projectile weapons in the point defense role and was fitted with seventy-five vertical launch system missile cells in its after decking, capable of accepting indirect fire support or SAM loads but without onboard reloads. Powered as Mark III, but with improved solar film. (It was no longer necessary to stop and deploy acres of film; the Mark IV could recharge on the move in average daylight conditions.) The Mark IV’s durachrome hull was thicker (30 millimeter), yet weight dropped to 210 tons in the Model B, with a maximum speed of 60 kph (road) and 30 kph (cross-country). Missile load and sensor upgrades continued to drive up the tonnage of successive models, however; by the end of its active life, the Mark IV did carry onboard missile reloads and weight had risen to over 340 tons while maximum road speed fell to 40 kph, with very limited rough terrain capability. (The Mark IV, Model H, for instance, could get through almost anything, but its suspension and power train weren’t up to crossing rough terrain at any kind of speed.)

MARK V BOLO (2160):

The first member of a family of specialists with roughly comparable onboard computer support but different weapons fits and functions. The Mark V was the first so-called “deep-wader”—that is, it no longer required bridging support, as it was designed to cross water barriers (including lakes and even small seas) by submerging and driving across their bottoms-and this capability became standard with all subsequent marks of Bolo. Power demands continued to grow, surpassing levels which even ionic battery technology could meet, and the Mark V was the first Bolo to use an onboard fission power plant. The growing size and weight of later models of the Mark IV had led to efforts to diversify design in the immediately subsequent marks, and the Mark V was the “general battle tank,” fitted with a heavy caliber railgun (190mm) for main armament, supported by twin lateral batteries of six 60mm “gatling-style” infinite repeaters using spent uranium slugs and lighter gatlings and laser clusters for point defense. The laser clusters’ anti-personnel function was limited, and the Mark V also saw the first use of multishot anti-personnel flechette/HE clusters, which became standard on all subsequent Bolos. Missile capacity was severely down-sized and restricted to SAMs as part of the drive to hold down weight. The Mark V had a one-man crew, a battle weight of approximately 198 metric tons, and a maximum speed of 50 kph (cross-country) to 80 kph (road).

MARK VI BOLO (2162):

The Mark VI was the direct descendent of the Mark III “mobile firebase” concept. It had the same power plant and computer support as the Mark V, but the Mark VI’s “main battery” was its missile load, which was configured for maximum flexibility. No railgun main armament was mounted, but the 60mm infinite repeaters were upgraded to seven guns per side, and a heavier point defense battery intended to provide cover for other friendly units and to protect the Bolo itself when operating in counter-battery mode was fitted. One-man crew; 238 tons; speed roughly comparable to the Mark V’s.

MARK VII BOLO (2163):

The Mark VII was a “heavy” Bolo, whose introduction inspired the first use-though still unofficially-of the term “siege unit.” It had the same electronics fit as Marks V and VI, but its main direct-fire armament was one 200mm railgun backed by fourteen heavier (75mm) infinite repeaters. The Mark VII’s heavy missile load was biased towards the bombardment function, but it was equally capable of operating SAMs in the area defense role. This vehicle has a very heavy layered durachrome war hull (120 millimeter) and required a two-man crew, rather than the Mark V’s and VI’s one-man crew, but in the VII/B the second crewman served solely to control the indirect fire armament. In later models, the second position was upgraded to a dedicated air-defense/missile intercept function. Weight was approximately 348 tons in the Model B, with a maximum road speed of 40 kph and a maximum cross-country speed of 30 kph. (The Mark VII was never very fast, but its sheer mass meant most terrain features tended to crumple when it hit them and so did not slow it as severely.)

MARK VIII BOLO (2209):

The Mark VIII was the next-generation “main battle” (or “standard”) Bolo. Main armament remained a railgun, though muzzle velocity increased still further and projectile size fell slightly (to 170mm), but this Bolo marked the first appearance of energy-weapon (laser) infinite repeaters. (By the time of the Mark VIII, any Bolo’s secondary battery had come to be referred to as “infinite repeaters” whether or not they fired actual projectiles.) Although the new laser infinite repeaters were actually marginally less effective than the last-generation railgun infinite repeaters on an energy-transfer-per-hit basis, mass per weapon fell, and the shift meant magazine capacity for the secondary battery was no longer a design factor. Missile capability was limited to the SAM and point defense role, but the Mark VIII received four hull-mounted 150mm rapid fire howitzers to compensate. The VIII/B was fission-powered, with solar charge backup capability, a one-man crew, and a weight of approximately 225 tons. Improved power train and suspension permitted a sustained road speed of 65 kph and short-range “sprint” speeds of up to 85 kph, but maneuverability at high speed was poor.

MARK IX BOLO (2209):

The Mark IX was the next generation “siege” unit, introduced simultaneously with the Mark VIII as companion vehicle. The main battery railgun was suppressed in favor of additional missile power and four high-trajectory 180mm howitzers in two back-to-back twin turrets. Further improvements in electronics allowed the Mark IX, unlike the Mark VII, to be crewed by one man. Weight was approximately 400 tons, and maximum road speed for the IX/B was 57 kph.

MARK X BOLO (2235):

The Mark X saw the first appearance of an energy main armament (laser cannon) in a Bolo. As with the laser infinite repeaters of the Mark VIII and IX, the new system was actually less destructive than the one it replaced on a per-hit basis, but it required no magazine space. The Mark X was fission-powered and carried laser infinite repeaters, and approximately 1/3 of the preceding Mark IX’s gatling closein anti-missile and anti-personnel weapons were replaced with multibarreled flechette-firing railguns in independent housings. The Mark X carried only self-defense missiles and no high-trajectory indirect fire weapons and required a one-man crew. Later models of this mark had sufficient computer capability and flexibility to begin use of pre-loaded computerized battle plans, requiring human intervention only when unanticipated tactical situations exceeded the parameters of the battle plan. The Mark X, Model B’s battle weight was 350 tons, with a maximum road speed 70 kph.

MARK XI BOLO (2235):

The Mark XI was essentially a backup, designed to cover the possibility that the Mark X’s laser main armament might prove impractical in service. Main armament was one 18cm railgun firing depleted uranium long-rod penetrators in the anti-armor role and a wide range of cluster, incendiary, chemical, and fuel-air rounds against unarmored targets. Otherwise, the Mark XI was identical to the Mark X. This vehicle remained in service longer than might otherwise have been anticipated because the projectile-firing capability of its main gun proved extremely popular with tacticians.

MARK XII BOLO (2240):

This was the first true “continental siege unit,” designed for strategic indirect fire with VLS cells capable of handling missiles with intercontinental range. The Mark XII was capable of MIRVed FROB attacks and of engaging orbital targets with hyper-velocity surface-to-space missiles. Main anti-armor armament was deleted, but the Mark XII was equipped with extremely capable anti-air/anti-missile defenses (in effect, it was an area defense system, as well as a bombardment unit). The vehicle was normally mated with a BAU (Bolo Ammunition Unit), a Mark XII with all offensive armament deleted to provide magazine space for multiple load-outs for the Mark XII’s missile batteries. Although the Mark XII continued to carry a one-man crew, it was primarily designed for pre-loaded computerized battle plans. Weight was 500 tons, with a road speed 50 kph.

MARK XIII BOLO (2247):

The Mark XIII was essentially a Mark XII with main anti-armor armament restored. Although the main gun ate up almost 25 percent of the tonnage dedicated to magazine space in the Mark XIII, the Mark XIII’s bombardment capability actually slightly exceeded that of the Mark XII with only minimal overall weight increases. This was made possible largely through improvements in fission technology (allowing a smaller power plant) and the first use of a flintsteel inner war hull under a much thinner durachrome sheath. The Mark XIII/B’s weight of 565 tons held fairly constant in all models of the mark. Road speed was 50 kph in the XIII/B, rising to 75 in late-series models as suspension and power train improvements became available.

MARK XIV BOLO (2307):

The Mark XIV replaced the never entirely satisfactory laser “main gun” of earlier marks with the far more destructive “Hellbore” plasmagun. This 25cm weapon, originally designed for the Concordiat Navy’s Magyar-class battlecruiser’s main batteries, had a half-megaton/second energy output and, unlike the earlier Bolo laser cannon, was a marked improvement over any kinetic weapon of equivalent mass. In other respects, the Mark XIV was a “standard” reversion to a generalist design, made possible by advances in mag-bottle technology (which finally made fusion power a practical alternative to fission in Bolo design) and acceptance of a lighter indirect fire capability. Anti-missile defenses were now sufficient to render strategic bombardment impractical, so indirect fire was limited to tactical and theater applications. This permitted the use of smaller missiles which, in turn, allowed an increased magazine capacity without weight penalties. Even so, the Mark XIV/B was 28 percent heavier than the Mark XIII/K it replaced, although further power train and suspension upgrades prevented any loss of maneuverability or cross-country performance. Gradual improvements in sensor fits and fire control systems kept this mark in front-line service for approximately 90 years. Tactically, primary reliance now rested firmly upon pre-loaded computerized battle plans, but a single human crewman was routinely carried to respond to unanticipated threats. The Mark XIV/B’s weight was 728 tons (rising to 900 in late-series models), and road speed hovered between 60 and 75 kph over the life of the mark.

MARK XV/BM BOLO (Resartus) (2396):

A quantum leap in Bolo technology, the Mark XV was the standardbearer of the Concordiat during humanity’s greatest wave of interstellar expansion. Very few non-human species encountered during this period could match the Mark XV’s capabilities; none could exceed them. This was the first Bolo which did not require an onboard human crewman, due to advances in cybernetics and secure communication links (first short-range subspace com capabilities), which permitted increasingly sophisticated computerized pre-battle planning coupled with unjammable remote human control to correct for unanticipated problems. Main armament was one 25cm Hellbore with line-of-sight capability, backed by laser cluster “gatling” infinite repeaters (total of fourteen in the Model B) and four 20cm howitzers in individual secondary turrets. The 25cm Hellbore remained incapable of engaging orbital targets from planets with atmosphere due to as yet unsolved attenuation and dissipation problems with the weapon’s plasma bolt “packaging,” but there were few planetary targets with which it could not deal. Tactical and theater bombardment capability was roughly equivalent to the Mark XIV’s, but the Mark XV had no strategic bombardment capability. The Mark XV’s six track systems each had an independent power train, and the vehicle carried both primary and secondary fusion plants. Cybernetics were divided between two totally independent command centers as protection against battle damage, and durachrome was wholly abandoned in favor of a much tougher flintsteel war hull. Early models of this mark saw the last use of anti-kinetic reactive armor. Major improvements in suspension were required to deal with unparalleled battle weights (1,500 tons in the Model B, rising to over 3,000 in the Model M), but road speed held constant at approximately 65 kph (with brief “sprint” capability of over 80 kph) over the life of this mark, although the “lightweight” Mark XV, Model L, EW platform, at barely 1,100 tons, was 37 percent faster. Cross-country speed was equivalent to road speed except in very rugged terrain. This mark enjoyed a very long, very stable evolutionary history (mainly because the Concordiat didn’t run into anything a Mark XV couldn’t handle).

MARK XV/R BOLO (Horrendous) (2626):

The Model R was the final variant of the Mark XV. Main armament was upgraded to one 50cm Hellbore (which, unlike earlier models’ weapons, could engage spacecraft in low orbit even from within a planetary atmosphere), and ablative armor appliques were fitted over the Model R’s flintsteel war hull in light of increases in infantry and light-vehicle energy weaponry. The preceding Model Q had seen vastly upgraded EW capabilities and the first appearance of heuristic cybernetics designed to run continuous analyses of pre-loaded battle plans against actual battle conditions in order to suggest improvements to its distant human commander. Under express human pre-battle authorization, the Mark XV/Q and /R were capable of reconfiguring their battle plans on the move without further human input. Although not self-directed, the final models of the Mark XV gave a very good impersonation of a war machine which was. Weights climbed sharply-the Mark XV/R reached 5,000 tons-but maximum road speed held fairly constant at 65-70 kph, despite weight increases.

MARK XVI BOLO (Retarius) (2650):

The increasing size of the Mark XV led to a fresh attempt at specialized design, and the Mark XVI was, in effect, a “light” Mark XV. Main armament remained a 50cm Hellbore, but the infinite repeater batteries were reduced to a total of eight weapons and the howitzer armament was deleted. (As partial compensation, the Mark XVI replaced its laser infinite repeaters with ion-bolt projectors, with much greater ability to penetrate ablative armor, and received a six-gun battery of short-range breech-loading 20cm mortars to augment its anti-personnel clusters.) A complete ablative outer hull was adopted to replace previous appliques, and cybernetics were equivalent to those of Mark XV/R. Weight fell to 3,600 tons, and road speed rose to 90 kph with short duration “sprints” of up to 100 kph possible. The Mark XVI formed the “light regiments” of the original Dinochrome Brigade.

MARK XVII BOLO (Implacable) (2650):

Introduced simultaneously with the Mark XVI, the Mark XVII was the “heavy” version of the same basic weapon system. Main armament was upgraded from a 50cm Hellbore to a 60cm weapon, and the ion-bolt infinite repeaters were increased to a total of fifteen (six each in two lateral batteries with a three-gun frontal battery in the glacis). The Mark XVI’s mortars were deleted in favor of six 25cm howitzers and an increased missile armament. Weight increased to 6,500 tons, and maximum road speed dropped to 75 kph. The Mark XVII formed the “heavy regiments” of the original Dinochrome Brigade.

MARK XVIII BOLO (Gladius) (2672):

While the Mark XVI was more agile and easier to deploy than the Mark XVII, it proved less popular in combat than its companion mark because of its lighter offensive power. The Mark XVIII replaced both the XVI and XVII in relatively short order as the new “standard” Bolo in an attempt to combine the best features of both its immediate predecessors. As usual, the new vehicle went up in size and weight (late-model Mark XVIIIs approached 10,000 tons), and space-to-ground deployment became a problem. Main armament was the Mark XVII’s 60cm Hellbore, but the infinite repeaters were reduced to twelve with the deletion of the bow battery (which had been found to compromise the structural integrity of the glacis plate). The Mark XVIII adopted a “sandwiched” hull: an outer ablative hull, then a thin hull of early-generation duralloy, and finally the flintsteel main war hull. The Mark XVIII also added a third fusion plant, which, with additional improvements in fire control, plasma containment technology, and weapons power, permitted its Hellbore to engage spacecraft even in medium orbit. The Mark XVIII formed the first “general purpose” regiments of the Dinochrome Brigade and, in successive models, remained first-line Concordiat equipment for over a century. Maximum road speed fell to 70 kph and maximum “sprint” speed fell to only 80 kph, but except in the roughest terrain, a Mark XVIII was as fast cross-country as on a road. (Of course, for vehicles as large and heavy as a Bolo, “roads” had long since become a purely relative concept.)

MARK XIX BOLO (Intransigent) (2790):

The Concordiat originally anticipated that the Mark XIX would remain first-line equipment for at least as long as the Mark XVIII, as it marked the first true qualitative improvement on the old Mark XV. The Mark XVI, XVII, and XVIII had been essentially up-gunned and up-armored Mark XVs; the Mark XIX was the first Bolo to mount mono-permeable, anti-kinetic battle screen as its first line of defense against projectile weapons and to incorporate the ability to convert a percentage of most types of hostile energy fire into useful power. In addition, the Mark XIX was accompanied into service by the Navy’s new specialized armor transport: a light cruiser-sized vessel mated to a pair of Mark XIXs and capable of rough-field landings in almost any terrain (short of swamp or truly precipitous mountains). The transports were a vast improvement over the older independent assault pods, thus greatly simplifying the deployment problems experienced with the Mark XVII and XVIII. Improved generations of pods remained in service for almost four more centuries, particularly for battalion or larger level assaults. Main armament remained a 60cm Hellbore, but secondary armament was upgraded to sixteen ion-bolt infinite repeaters, backed up by 35mm gatling/railguns. The howitzer armament was once more suppressed in favor of eight 30cm breech-loading mortars, and the ablative outer hull was further augmented by a “plasma-shedding” ceramic tile applique. Weight soared to 13,000 tons, but road speed actually rose to 90 kph, with a “sprint” capability of over 120 kph.

MARK XX/B BOLO (Tremendous) (2796):

The reign of the Mark XIX was shorter than anyone had anticipated primarily because no one had anticipated the psychotronic breakthrough. (Or perhaps it would be more accurate to say that no one had expected the High Command to accept the psychotronic technology as quickly as it did.) The Mark XX Tremendous was the first truly self-directing (and self-aware) Bolo. Defensive capabilities remained unchanged from the Mark XIX, but the internal volume demands of the Mark XX’s psychotronics forced the main armament to be downsized, and the Mark XIX’s single 50cm Hellbore was replaced by two 30cm weapons, twin-mounted in a single turret. In addition, the Mark XX/M (unofficially referred to as the “Mosby”) was a unique departure. Designed for independent deployment to raid an enemy’s logistics and rear areas, the XX/M was essentially a refitted Mark XIV hull. The considerable mass of its first-generation Hellbore, along with its turret, was deleted, which freed up sufficient internal volume (barely) to permit installation of a somewhat less capable version of the Mark XX’s psychotronics. Although self-aware, the Mark XXs had relatively simple (and bloodthirsty) personalities, and full self-awareness was specifically limited to battlefield applications. Except in carefully defined combat-related areas, the Mark XX’s software suppressed its volition, effectively prohibiting it from taking any action without direct orders from designated human command personnel. Weight and speed data for the Mark XIX apply to the Mark XX. The Mark XX’s great opponents were the Yavac heavies of the Deng, but not even the Yavac-A/4 could survive against a Mark XX Bolo without a numerical superiority of at least 3.25-to-1.

MARK XXI BOLO (Terrible) (2869):

Following the introduction of the Mark XX, a nomenclature policy was adopted under which new mark numbers were to be issued only to reflect substantial increases in psychotronic capability. (The new practice was temporarily abandoned with the Mark XXVII-Mark XXIX series, but resumed with the Mark XXX.) The Mark XXI actually proliferated into several sub-variants which would have received their own mark numbers under the old system, including yet another attempt at a “heavy” Bolo (which tipped the scales at over 20,000 tons and was never adopted for field use), and the “stealth” forward reconnaissance XXI/I. Mainstream Bolo development, however, followed the “standard” format, and the Mark XXI/B reverted to the single 60cm Hellbore main armament of the Mark XIX. The major advance lay in the enhanced computational speed of the mark’s computers and improvements in the personality centers of successive models. Although still fringed about by inhibitory programming to control self-directed actions outside combat, the Mark XXI was much more capable in combat. This mark also saw the introduction of TSDS (Total Systems Data-Sharing) technology into the regiments of the Dinochrome Brigade. In practice, each unit of the regiment operated in battle as a single component of a multiunit awareness in a free-flow tactical link which combined the conclusions of all its Bolos to formulate future actions.

MARK XXII BOLO (Thunderous) (2890):

The Mark XXII saw both further advances in cybernetics and psychotronics and a considerable upgrade in firepower with the new “super” Hellbore, a 90cm weapon which increased its destructive output to a full two megatons/second. Secondary armament mirrored the Mark XXI’s. The Mark XXII was also the first Bolo to mount an interplanetary-range subspace com, and, for the first time, the Navy modified its cybernetics to permit a Bolo’s psychotronics to directly control the maneuvers and defensive systems of its armor transport spacecraft (now unmanned in combat) for assault insertions, which increased its chance of penetrating hostile defenses by an order of magnitude. The Mark XXII’s kinetic battle screen showed a 36 percent increase in effectiveness over the Mark XXI’s, and weight hovered around 14,000-15,000 tons for all models, with a top speed of 80 kph and a “sprint” capability of 120-135 kph.

MARK XXIII BOLO (Invincibilis) (2912):

The Mark XXIII followed quickly on the heels of the Mark XXII, largely as a result of worsening relations between the Concordiat and the Quern Hegemony. Although the Quern managed to achieve strategic surprise when they actually launched their attack, worsening Human-Quern relations between 2880 and 2918 had driven Bolo research at a breakneck pace. The original Mark XXIII was only a marginal improvement (in electronic terms) on the Mark XXII, but the main armament was doubled to a pair of 80cm “super” Hellbores in fore-and-aft turrets, and provision was made for quick conversion to the molecular circuitry whose early perfection the R amp;D bureaus anticipated. Secondary armament was also upgraded-to eighteen ion-bolt infinite repeaters in two nine-gun lateral batteries-and a new generation of battle screen was augmented by internal disrupter shielding around critical systems. The outbreak of the Quern Wars put a halt to major psychotronic research, as all efforts were bent upon design rationalization to aid in mass production, but the anticipated molecular circuitry appeared almost on schedule. Although it was not applied throughout, late-series Mark XXIIIs incorporated the new circuitry within their psychotronics, which enormously increased capability without increasing volume requirements. It was possible to restore the “secondary brain” feature to the Mark XXIII with no degradation in base capability, which made it much more resistant to battle damage. Despite its increased armament, the Mark XXIII, like the Mark XXII, hovered around the 15,000 ton mark, primarily because of the weight savings of its new molycircs and the shift to later-generation duralloy in place of flintsteel, which permitted armor thicknesses to be halved for the same standard of protection. Speeds remained largely unchanged from the Mark XXII.

MARK XXIV BOLO (Cognitus) (2961):

The Mark XXIV was the first genuinely autonomous Bolo. Previous Bolos had been self-directing on the tactical level, but the Mark XXIV, with a vastly improved personality center and id integration circuitry, was capable of strategic self-direction. For the first time, Bolos began to evolve a truly “human” level of individual personality, but the Mark XXIV’s psychotronics continued to be hedged about with inhibitory safeguards. A much greater degree of non-combat autonomy was permitted, but the vehicle’s psychotronics remained so designed as to deny it full use of its own capabilities outside Battle Reflex Mode. Impetus to decrease or even abolish those safeguards clearly began with this mark as it proved its reliability and flexibility, yet resistance would continue until Bolo Central reviewed the battle record of Unit 0075-NKE on Santa Cruz in 3025. The Mark XXIV retained the Mark XXIII’s secondary armament but reverted to a single-turreted main armament (90cm “super” Hellbore). Despite the reduced main armament, weight fell only to the 14,000 ton mark, and speed remained roughly equivalent to that of the Mark XXII and Mark XXIII.

MARK XXV BOLO (Stupendous) (3001):

After forty T-years of experience with the Mark XXIV, even diehards conceded that many of the inhibitory software features which had been incorporated into every Bolo since the Mark XX were no longer justified. The most restrictive features were deleted from the Mark XXV, Model B, although it was not until the Model D (introduced in 3029) that virtually all inhibitions were suppressed. A core package of override programming was retained to restrict the volition of (or even, in the case of the so-called “Omega Worm,” to destroy) a Mark XXV which went “rogue” as a result of battle damage or “senile” due to poor maintenance, but most of the restrictions which had required human approval for almost all non-battle decisions were progressively relaxed over the operational life of the Mark XXV, with a tremendous increase in efficiency. The practice of deploying totally independent Bolo brigades lay well in the future, but the Mark XXV’s capabilities clearly pointed the way to them. The Mark XXV essentially duplicated the offensive and defensive systems of the Mark XXIV, yet further improvements in metallurgy and fusion technology dropped weight to 13,000 tons while normal speed rose to a maximum of 95 kph, though “sprint” speed remained unchanged.

MARK XXVI BOLO (Monstrous) (3113):

The Mark XXVI was the first Bolo to incorporate improved “hyper-heuristic” features based on the work of Major Marina Stavrakas. Armament, size, weight, and speed remained largely unchanged from the Mark XXV, but the Mark XXVI was capable of constructing a “learning model” in accelerated time. In some ways, this almost equated to precognition, in that the Mark XXVI could project changes in an enemy’s tactical or strategic actions before even the enemy realized he intended to change them. The new systems also meant that, accompanied by a much improved ability to break hostile communications security, a Mark XXVI could actually invade an opponent’s data net, access his computers, scan them for useful data, and (in some cases) even implant its own directions in those computers.

MARK XXVII-MARK XXIX BOLOS (3185-3190):

The Mark XXVII (Invictus), XXVIII (Triumphant), and XXIX (Victorious) marked a temporary reversion to the older practice of assigning mark numbers on the basis of armament and function rather than psychotronics technology. All three had essentially identical cybernetics, which concentrated on further improvements to their hyper-heuristic packages, but the Mark XXVIII and XXIX also incorporated a complete changeover to molecular circuitry throughout, aside from the power linkages to their energy armaments. All three of these marks were used in the new, independent brigades which replaced the old regiment structure of the original Dinochrome Brigade, but, in some ways, the units marked a reversion to the old “specialist” designs. All mounted the new 110cm “super” Hellbore (2.75 megatons/second), but the Mark XXVII was a “light,” fast Bolo, with greatly reduced secondary armament, limited indirect fire capability, and a vastly improved sensor suite, intended to serve in a scouting and screening role for the independent brigades. (This function had been performed by light manned or unmanned vehicles, and the old Mark XXI/I, with psychotronic upgrades, remained in service for special forces applications. The new strategically self-directing Bolo brigades, however, required an integral scouting element, one not limited by “stealth” considerations and capable of fighting for information at need.)

The Mark XXVIII was the “generalist” of this trio of marks, with much the same armament as the old Mark XXIV, although that armament was even more deadly and effective under the control of the improved psychotronics of the newer units.

The Mark XXIX was an unabashedly “heavy” Bolo-indeed, it remained the heaviest Bolo ever deployed prior to the Mark XXXIII. It reverted to the twin Hellbore armament of the Mark XXIII (though still in 110cm caliber), coupled with a much enhanced indirect fire capability, and an integral logistics/maintenance function which it could extend to other units of the brigade. (The maintenance/repair function became standard in all succeeding Bolo designs.) The independent brigades normally consisted of four regiments of three 12unit battalions each: one of Mark XXVIIs, two of Mark XXVIIIs, and one of Mark XIXs. Weights for these Bolos were 11,000 tons (maximum normal speed 110 kph) for the Mark XXVII, 15,000 (maximum normal speed 90 kph) for the Mark XXVIII, and 24,000 (maximum normal speed 75 kph) for the Mark XXIX.

MARK XXX BOLO (Magnificent) (3231):

Introduced on the eve of the Human-Melconian “Last War,” the Mark XXX was the direct descendant of the Mark XXVIII. The incorporation of counter-grav into the Mark XXX’s suspension and power train went far towards offsetting the mobility penalties increasing weight had inflicted on preceding generations. The Mark XXX incorporated still further improvements to the hyper-heuristic capabilities of the Marks XXVII-XXIX, new dual-ply battle screen (which was not only more effective against kinetic weapons but also capable of absorbing at least some of the power of almost any energy weapon and diverting it to the Bolo’s use), and a new and improved cold-fusion power plant. Weight dropped from the Mark XXIX’s 24,000 tons to 17,000 and normal speed increased to 115 kph. For very short intervals, the Mark XXX could divert sufficient power to its counter-grav units to achieve actual free flight at velocities up to 500 kph, but could not operate its battle screen or internal disrupter shields or fire its main armament while doing so.

MARK XXXI BOLO (3303):

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 glacis and turret faces. All secondary and tertiary weapons were mounted outside the “core hull” which protected the Mark XXXI’s power plants and psychotronics, and last-generation internal disrupter shielding was used heavily. The Mark XXXI retained the counter-grav assist of the Mark XXX and, despite a weight increase to 19,000 tons, could match the preceding mark’s speed.

MARK XXXII BOLO (3356):

The last Bolo whose year of introduction is known with certainty, the Mark XXXII was essentially a Mark XXXI with the added refinement of direct human-Bolo neural-psychotronic interfacing. Provision was also made for attachment of a counter-grav unit sufficient, under emergency conditions, to permit the Bolo to make an assault landing without benefit of transport. Offensive and defensive systems were comparable to those of the Mark XXXI. The Mark XXXII was the final version of the “standard” Bolo.

MARK XXXIII BOLO (?):

The last-and largest-Bolo introduced into service. The Mark XXXIII weighed no less than 32,000 tons and mounted a main armament of three independently-turreted 200cm Hellbores with a secondary armament of sixteen 30cm Hellbore infinite repeaters in two lateral batteries. Equipped with a very sophisticated indirect fire system, the sheer firepower of the Mark XXXIII was a reversion to the old siege unit thinking, though it was normally referred to as a planetary siege unit, not merely a continental one. No one knows how many Mark XXXIIIs were actually built, but official planning called for them to be deployed in independent brigades of 24 units each. Despite the increase in weight, speed remained equivalent to the Mark XXXI, and the Mark XXXIII’s internal counter-grav could supply the assault landing capability for which the Mark XXXII had required an auxiliary unit.

General Armament Notes

In addition to the weapons listed, all Bolo secondary armaments include small-caliber high-velocity projectile weapons for close-in defense and anti-personnel fire. All Bolos after Mark V also mounted multiple-shot flechette anti-personnel “clusters” with progressively heavier flechettes.

Any Bolo secondary gun with anti-armor capability was always referred to as an “infinite repeater,” although the term originally applied only to a small– to medium-caliber projectile weapon with a high rate of fire and large magazine space.

Like most of their other weapon systems, the vertical launch system missile outfits of Bolos evolved tremendously over the course of the Bolo’s design history. The original Mark III VLS consisted of only 60 non-reloadable cells, although more than one missile might be loaded per cell if they were small enough. By the time of the Mark XIX, the VLS consisted of reloadable, magazine-fed cells, and all future Bolo VLSs followed that pattern. The term “light” or “heavy” used to describe a VLS refers to (1) the number of cells (and thus salvo density) and (2) the VLS magazine capacity, not to the weight or size of missiles thrown.

The breech-loading mortars fitted to most Bolos after the Mark XIII might be considered automatic weapons, as their rate of fire averaged from 8 to 12 rounds per minute. The Mark XXXIII’s 15cm BLMs had a maximum effective range of 3,000 meters; the 40cm BLMs of the Mark XXIX and Mark XXXIII had a maximum effective range of 9.75 kilometers.