Reading through Conan The Mercenary, I found the section on siege craft and artillery and noticed something. If taken at face value Hyperborian siege engines and field artillery are extremely portable, powerful, numerous and able to be used effectively (or at all) with very small crews compared to history. For example, the description of the trebuchet gives it the ability to breach a wall in a single hit, an average projectile weight of over 300 lb., the ability to move, and the same range band as a Shemite bow all while having a crew of 4. In real life the trebuchet Loup de Guerre or “War Wolf” was commissioned by English king Edward I during the Scottish Wars of Independence. Considered the largest trebuchet ever built, Ludgar, as it was known by its Anglo-Saxon crews, stood from 300 to 400 feet (91.44 to 121.92 meters) in height, launched a 300 lb. (135 kg) projectile 200 meters, could only be moved after complete disassembly and in 30 carts, and had a crew of at least 10. Ludgar caused an entire Scottish castle to attempt to surrender to Edward during its first field assembly. The good king, of course, refused, wanting to see first hand what his newly built war machine could do. The castle lost.
The smaller field artillery, while less ludicrous than the average Hyperborian trebuchet, are still crazy compared to their historical counterparts. Like the trebuchet, the ballista and scorpio’s power, accuracy and ability for battlefield relocation at a rate that is relevant for field use (That is, moving at all as the ballista, scorpio and trebuchet were emplaced weapons rather than mobile field artillery, none of them had wheels.), along with their smaller crews (While the humble scorpio was fired by a single person, the crews were larger) would cause Hyperborian field and siege combat to be radically different than its historical inspiration. The ability of Hyperborian mercenaries to mount their large numbers of scorpios on chariots only exacerbates the crazy, reminding me of the Russian tachanka.
Hyperborian mercs love of organization, mobile and highly mobile field artillery, crossbows (Standard and repeating) and arbalests makes imagining battles both harder, having no easy representation for how these would affect Hyperborian military science, but also a heck of a lot more fun, at least for me.
Edit:
So, uh, belay that statement of Hyperborian field artillery being less insane than their heavy. Pg. 16 of Conan the Mercenary shows what a ballista fires, that being what amounts to a 12-13 ft. long, 70-75 mm diameter lance. The ballista is also huge compared to known Roman artillery (outside of dedicated siege engines, though those threw shaped stone rather than bolts).