The Development of Projectile Weapons: Ancient Catapults

Abstract

One of the first projectile weapons was the sling; there is evidence of slings dating from about 10,000 BCE. The sling is a very basic weapon, consisting of a piece of cloth or hide to which two unequal strings are attached. A small shot is placed in the sling, which is then whirled about the head and one of the strings released in the direction of the target. An important innovation occurred at about 6,000 BCE, when it was found that conical shot was more accurate than round shot, and the first manufactured ammunition was made from baked clay from 5,000 BCE. The sling was a dangerous weapon; Alexander himself was only saved from death by his helmet when hit on the head by a slingshot during the siege of Kyropolis in 329 BCE. The bow and arrow is even older than the sling, with cave paintings of bows dating back to the Palaeolithic (Rihill 2007: 13). Composite bows, made of wood, sinew and horn, smaller and more powerful than the ‘self-bow’ constructed from a single piece of wood, appeared in the fourth millennium BCE. I resist the temptation to date the beginnings of weapons research with reference to any of these innovations regarding the bow or the sling – I expect some case could be made if only the evidence was available, but the precise date at which weapons research began is not something that needs to be established here. However, when the sling and bow evolved into the catapult, and especially with the advent of torsion artillery, it is clear that weapons research had arrived. In this chapter I will say something about catapult technology in order to show that weapons research has been around for a long time. The development of this technology will also help us understand just what weapons research is. Moreover, there are four remarkable treatises on the catapult written between the third century BCE and the first century CE by Philon, Biton, Heron and Vitruvius which amount to the first weapons design manuals. To conclude, I will outline the evolution view of technology, and illustrate it with reference to the catapult. To set the scene I recount one of the best-known episodes in the ancient world of military technology skilfully deployed to thwart a powerful enemy.

Appendix: The Technical Treatises

There are in all five ‘technical treatises’ that have come down to us from antiquity.²¹ These are Heron of Alexandria’s Cheiroballistra and Belopoeica (either second half of first century CE or, less probably, first half of second century CE) Vitruvius the Roman engineer De Architectura (about 25 BCE), Philon of Byzantium’s Belopoeica (270–240 BCE?), Biton’s Construction of War-machines and Artillery (about 240 BCE?). Rather more is known about the two later works than the earlier ones. I will say a little about each of them.

Heron’s work Cheiroballistra is just a three page list of components for a machine of the same name, which was a small, sophisticated catapult, to be used by an individual artilleryman. So it is a finished design or blueprint (‘engineering specification’) that could be followed by a skilled craftsman – indeed, Marsden reports that a full-sized working replica has been made. I note here again that it is significant that this, and others of the machines mentioned in the treatises, have been made following the instruction of the original treatises. Marsden says that sometimes it has been necessary for the modern artificer to use modern substitutes for materials no longer readily available, such as the types of sinew used to generate the restoring force of the machines – the springs – and sometimes also to make allowances for mistakes in the extant versions of the treatises, something that he would put down to copying errors (‘mutations’). Leaving these minor points aside, the fact that it is possible to follow the instructions and build cheiroballistras and other machines many centuries after they were written down substantiates the idea that the design, unlike their individual manifestations as artefacts – there are no ancient working cheiroballistras about – endure in space and time: treatises written in the Near East two millennia ago provide the blueprints for constructing machines in Northern Europe. Turning to Heron’s other work, Belopoeica (artillery manual) is more general, and he gives some dimensions for making a variety of machines – the belly bow, early torsion artillery, straight spring engines, etc. There is also some mathematics in the form of the theorem of two mean proportionals and reference to the doubling of the cube, though the geometrical representation is a little dense.

In contrast to both of Heron’s treatises, Philon’s is longer and more general. Thus, while Heron gives the specific dimensions for just one machine, in the Cheiroballistra, Philon, as we have seen, gives a formula for constructing machines of a given type, namely the stone-throwing catapult, and a perspicuous method for dealing with it. He also gives hints for scaling up from models and making machines on the basis of existing examples, and there are quite a lot of details about making and mounting the springs. Philon’s work is thus more useful to the builder of artillery than Heron’s because it encompasses a wider range of possibilities. A common feature of these treatises, one that they all shared, is that the authors did not invent the machines that they describe. Philon, for example, is supposed to have spent time on the island of Rhodes which was known to have many skilled craftsman and which was famous for its advanced war machinery, and also at the arsenal in Alexandria. One supposes that Philon observed, took part in and learned much from the work carried on in both places. And one supposes that the Rhodian and Alexandrian engineers had learnt their trade from others. So his Belopoeica is in part at least a summary of the incremental achievements of others, though Marsden thinks that Philon did do some original work.

Now to the Roman Vitruvius, it appears that he was a military architectus engaged to construct and repair catapults and hence had direct practical knowledge of his field. The three books on artillery in his ten book De Architectura are short and authoritative: he gives a list of the sizes of the hole for the springs for various catapults which “I personally have found correct in practice and which, in part, I have received from my instructors as fully vouched for”. Of course one would expect this of someone who was employed by Julius and Augustus Caesar. The works of Vitruvius and other Roman engineers were reprinted well into the middle ages (Nossov 2005: 52). Finally to Biton. His is a relatively short treatise with blueprints for two types of stone throwers, one type of bow and a sambuca (siege ladder). There are no general formulae and hence his work is perhaps the least comprehensive of the four writers.