The Bolo, Mark XXIV (Cognitus), introduced in 2962, was the first genuinely autonomous Bolo. Where previous Marks had allowed tactical autonomous direction, the Mark XXIV's improved personality center and id integration circuitry permitted truly independent, strategic self-direction.

The Mark XXIV mounted one 90cm "Super" Hellbore as main armament, eighteen ion-bolt infinite repeaters, six 30cm BL mortars, and a VLS missile launch system. It masses 14,000 tons and has a road speed of 80 kph, with sprints to 148 kph. Hellbores fire slivers of steel-jacketed cryo-H, a few grams of hydrogen held as slush at near absolute zero temperatures. Magnetically accelerated to relativistic speeds by superconducting coils within the weapon's barrel, the cryo-H is compacted and heated until it reaches fusion temperatures. The devastating effect of the Hellbore is the natural outcome of shooting at a target with tiny pieces of burning star traveling at near-light velocities. Damage, measured at several megatons/second, is caused both by fusion effects and by the release of considerable kinetic energy at impact. The Mark XXIV measured almost seventy-five meters from its clifflike prow to the bulbous housings of its stern anti-personnel clusters. Its interleaved bogie wheels were five meter in diameter, and the top of the massive 90cm "Super" Hellbore towered thirty meters above the fused ceramacrete of the chamber floor. The hexagonal scales of its multilayered ceramic antiplasma armor appliques were the mottled green and brown of standard jungle camouflage.

Technical information from Bolos, Book III: The Triumphant, published by Baen Books, September 1995 pages: 378-379. Descriptive information from Bolos, Book I: Honor of the Regiment, published by Baen Books, September 1993 in the story "Camelot" by S.N. Lewitt pages 37-62. An additional descriptive detail comes from the complete series of books about the Bolo. Scratchbuilt on the chassis of two 1/72 scale Tiger I Tanks, with the treads of a third. It is in 1/300 scale. Over 100 hexagonal scales were cut and placed by hand. To show the relative scale of the model, I put it next to a $10 bill.