Charles and Singleton have recently subjected the common modern assumption that elephants were used during the Claudian invasion of Britain in a.d. 43 to careful scrutiny.Footnote ¹ As they highlight, the only ancient evidence for this consists of a brief mention of elephants by the senatorial historian Cassius Dio, writing in the early third century a.d. In his account of this invasion, Dio describes how the commander of the Roman forces, Aulus Plautius, had advanced as far as the Thames, but had then stopped to send for reinforcements led by the emperor Claudius himself (Cass. Dio 60.21.2):

Unfortunately, Dio's description of how equipment, including elephants, had been readied to reinforce Plautius’ efforts is extremely vague. He does not identify who exactly had gathered this equipment, when they had begun doing so, or where they had gathered it. The most obvious interpretation is that this equipment had been gathered somewhere on the continental side of the English Channel, simultaneous with the preparation of the main force led by Plautius. The intention was that it would be used by Claudius himself, when he was eventually summoned to lead the final stage of the invasion, the capture of Camulodunum, the capital and principal stronghold of the main enemy, the Catuvellauni. Dio does not explicitly confirm that Claudius did bring elephants with him to Britain in the end, although that is the clear implication of what he says. But is he correct? Did the Romans really prepare to bring elephants to Britain?

Charles and Singleton make a strong case that it is extremely unlikely that Claudius brought elephants with him, or that he ever had any intention of doing so. They point to the evidence that Claudius spent only 16 days in total in Britain, arguing that he would probably not have had enough time to march to and from Camulodunum during this period if accompanied by elephants.Footnote ³ More importantly, they point to the fact that the Romans had rarely ever employed elephants for military purposes and that there is no other evidence that they used them for such purposes during the early principate.Footnote ⁴ One might possibly object that the second-century a.d. rhetorician Polyaenus reports that Caesar used an elephant to force a crossing across a river in Britain, presumably during his second expedition to Britain in 54 b.c. However, as Charles and Singleton point out, it is difficult to reconcile this claim with Caesar's failure to mention his use of elephants at any time during his conquest of Gaul, including his expeditions to Britain, in his own detailed account of these campaigns.Footnote ⁵ Polyaenus is probably incorrect, and his evidence should not be allowed to influence the assessment of Dio's testimony.Footnote ⁶ Finally, Charles and Singleton also point to the absence of elephants from any media, such as coins or sculptures, celebrating Claudius’ conquest of Britain.Footnote ⁷ The obvious conclusion, therefore, is that Dio errs when he implies that Claudius had brought elephants to Britain with him. That raises the question how or why he should have made such an error.

Charles and Singleton devote little attention to this question, limiting themselves to quoting approvingly the suggestion by Edmondson that Dio, or his source, ‘garbled a report that elephants were used in [Claudius’] … triumphal procession at Rome and erroneously transposed the elephants to the warzone’.Footnote ⁸ While this is not impossible, it is not something to be easily assumed either, certainly not before all other logical possibilities have been investigated. Such was the military and political experience of Dio himself, a former governor of Africa, of Dalmatia and of Pannonia Superior, that it is difficult to believe that he would easily have assumed that Claudius took elephants with him to battle in Britain as if this was an entirely routine decision for any Roman commander when setting out on campaign.Footnote ⁹ More importantly, there is no evidence that Claudius did use elephants in his triumphal procession. Dio (60.23.1) reports that he carefully followed custom in his celebration of his triumph, which is entirely believable of an emperor who had such strong antiquarian interests. However, while the triumphant general had traditionally used horses to pull his chariot, Pompey had set a new precedent when he had used elephants to pull his chariot during his triumph in c. 80 b.c.Footnote ¹⁰ Consequently one cannot entirely exclude the possibility that Claudius used a chariot drawn by elephants during his triumph in a.d. 44. Furthermore, there was also a long tradition of including captured elephants among the spoils paraded in a triumphal procession. While we can be quite sure that the Romans did not capture any elephants from the Britons in a.d. 43, we cannot exclude the possibility that they added them to the procession for the sake of colour or because they now regarded them as generic symbols of victory.Footnote ¹¹ Nevertheless, there is no firm evidence that Claudius did include elephants within his triumphal parade. Consequently one needs to explore other possibilities also in any effort to explain Dio's apparent mistake in including elephants among the equipment intended for Britain.

Any new analysis of this problem needs to begin with Dio's actual words. Since Dio includes his reference to the elephants as part of a description of military equipment, we are forced to ask whether the Greek term ἐλεφάντων may not conceal a corrupt reference to some form of military equipment. Yet nothing obvious suggests itself. That leaves one other possibility, that Dio, or his source, used the term ‘elephant’ to describe not the animal of that name, but a particular piece of military equipment named after that animal. In support of this, one notes that it was common practice in the Roman army to name military machines after various types of living creatures. Hence the term for a battering ram was aries ‘ram’, after the animal of that name; the grappling-hook used to ascend walls was the gruis ‘crane’, after the bird; the term for the grapnel that defenders used to seize a ram and drag it off was lupus ‘wolf’; the term for the siege-shed used to protect Roman troops sheltering within it was the testudo ‘tortoise’; the term for a mantlet was musculus, meaning either ‘little mouse’ or ‘pilot fish’; the term scorpio ‘scorpion’ was used to describe a type of catapult; and the same, or similar device, was later known as an onager ‘wild-ass’ rather than a scorpion.Footnote ¹² In a similar manner, Roman soldiers invented the phrase caput porci ‘pig's head’ to describe a particular type of cuneus or wedge-shaped tactical formation.Footnote ¹³ Finally, one should not forget that the Romans nicknamed the naval boarding-bridge that they invented during the First Punic War as the corvus ‘raven’.Footnote ¹⁴

Each of the above-mentioned pieces of equipment was so named because it was thought to resemble the relevant animal in some important way. The ram was so called because it battered its target in the way that a ram butts its rival, or, as Vegetius states ‘because it backs off like a ram in order to strike with greater force’.Footnote ¹⁵ The tortoise was so called because it protected those within it in the manner that its shell protects the tortoise or, as Vegetius states, in a description of a particular type of tortoise sheltering men operating a ram, because ‘just as it [the tortoise] now withdraws, now sticks out its head, so the machine at one moment withdraws its beam, at another sends it out to strike more strongly’.Footnote ¹⁶ The scorpion was so called because its elevated throwing arm resembled the sting of a scorpion, but it eventually became known as an onager because, or so Ammianus claims, it hurled stones in the same way that wild asses kicked stones up behind them, so hard that they often killed their pursuers.Footnote ¹⁷ Next, the musculus probably derived its name from the fact that it was shaped like a mouse.Footnote ¹⁸ However, the fact that Vegetius prefers to interpret this term in reference to pilot fish who ‘though quite small, provide continual help and support to whales’, leads him to compare the mantlets to pilot fish in that they ‘as if assigned to the big towers, prepare the way for their arrival and build roads for them’ in the same way that pilot fish prepare the way for whales.Footnote ¹⁹ Finally, the corvus received its name because the spike that held the bridge fast by piercing through the decking of the enemy ship was thought to resemble the beak of a raven.

So, if Dio's description of the presence of elephants among the equipment being prepared for the campaign in Britain does not refer to the animal by this name, but to a type of equipment named after this animal, what was the nature of this equipment? The defining characteristic of the elephant was its great size, particularly its height, suggesting that any device named after it would have been noteworthy for its great height also. Furthermore, war elephants sometimes bore towers upon their back from which archers and slingers could discharge their weapons.Footnote ²⁰ Both factors, great height and service as a platform for the discharge of missiles, immediately suggest some form of siege-tower, the greatest of the Roman military machines. Here one notes that the Romans had deployed elephants at a siege on at least one occasion earlier, at Numantia in 153 b.c., but that this had proved disastrous when an injured elephant had turned against the Roman side.Footnote ²¹ More importantly, however, elephants seem to have become a standard part of the Sassanian siege train when attacking Roman towns by the mid fourth century a.d., and were sometimes used as substitute siege-towers.Footnote ²² In summary, the physical similarity of an elephant to a siege-tower, and its potential use as a temporary siege-tower even, were so obvious that it would not be surprising to discover the term ‘elephant’ being used as a nickname for a siege-tower.

But would Claudius really have brought siege-towers to Britain in a.d. 43? Insofar as the Romans expected to have to besiege Camulodunum, it makes sense that they should have included some siege-towers among the equipment readied for the final stage of the invasion.Footnote ²³ However, it does not make sense that they should have attempted to transport fully constructed siege-towers from wherever it was on the continent that they had stockpiled this equipment to Britain. Rather, when Dio describes the presence of elephants among this equipment, one should understand him to refer to the components for building such siege-towers, rather than the fully constructed machines.

It is my argument, therefore, that when Dio records the presence of elephants among the equipment readied for the final phase of the Claudian invasion of Britain, he may well refer to some form of siege-tower rather than to the animal by this name. Unfortunately, there is no evidence that the Romans ever called any of their siege-towers by this name, but he, or rather his source, may have preserved a rare piece of military slang from the first century a.d. for what was a relatively unusual piece of military equipment without necessarily realising that this is what they have done. In short, Dio may well have believed that Claudius had intended to bring real elephants to Britain, but that need not have been the case at all, certainly not on the evidence that he preserves.