by David Weber
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 mai
n 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 smal
l-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.
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