Siege Projectors: A Primer

This is just an old post dug up from the pre-1990 halcyon days of my online existence. I think I wrote the original in 1981!

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Ballista: From the Greek word for 'thrower'. This device fired large bolts in a reasonably straight line. It was really a giant crossbow, relying on a combination of torsion and springs to store energy. The scorpion is a smaller version, still quite large, but operated by a single 'sniper'. In theory, a ballista could fire ten bolts, massing several kilograms each, per minute. The effective range was as high as 500m. With Roman technology, that would have been the norm, and their accuracy was impressive. With modern steel, a ballista should be able to fire lighter and stronger bolts over four times that distance.

Catapult: From the Greek word for 'flinger'. Another device using torsion to project a load in a ballistic trajectory. Although the catapult and the ballista were indistinguishable at some point in their common Greek military history, the catapult (and its kin, the onager and mangonel) evolved terminologically to be a sling-like device firing round shot. Siege catapults traditionally fired loads such as rocks with less than a hundred kilograms of mass. A slightly more advanced grasp of mathematics was required than that needed for the operation of a ballista.

Trebuchet: From an Old French root, meaning 'to throw over'. A device using a counterweight mechanism to rotate an opposing arm, which would fling the load in a trajectory dictated by the mechanism design. The trebuchet was invented by the Chinese in the 3rd Century BC, and used by the English in the 11th Century to devastating effect; the machine could throw loads of 150 kilograms more than 200 metres. One such device, the Warwolf, so intimidated Scottish defenders that they tried to surrender when they saw it being assembled.

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I actually wrote more on onagers, mangonels, and scorpions; over the years, I simplified things a lot in my mind. It helped that my illustrious father was (and still is) a military historian. Plenty of source material there!