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.
