The Battle of the Hydaspes (326 BC), which I’ve discussed here is instructive. Porus’ army deployed elephants against Alexander’s infantry – what is useful to note here is that Alexander’s high quality infantry has minimal experience fighting elephants and no special tactics for them. Alexander’s troops remained in close formation (in the Macedonian sarissa phalanx, with supporting light troops) and advanced into the elephant charge (Arr. Anab. 5.17.3) – this is, as we’ll see next time, hardly the right way to fight elephants. And yet – the Macedonian phalanx holds together and triumphs, eventually driving the elephants back into Porus’ infantry (Arr. Anab. 5.17.6-7).

So it is possible – even without special anti-elephant weapons or tactics – for very high quality infantry (and we should be clear about this: Alexander’s phalanx was as battle hardened as troops come) to resist the charge of elephants. Nevertheless, the terror element of the onrush of elephants must be stressed: if being charged by a horse is scary, being charged by a 9ft tall, 4-ton war beast must be truly terrifying.

Yet – in the Mediterranean at least – stories of elephants smashing infantry lines through the pure terror of their onset are actually rare. This point is often obscured by modern treatments of some of the key Romans vs. Elephants battles (Heraclea, Bagradas, etc), which often describe elephants crashing through Roman lines when, in fact, the ancient sources offer a somewhat more careful picture. It also tends to get lost on video-games where the key use of elephants is to rout enemy units through some “terror” ability (as in Rome II: Total War) or to actually massacre the entire force (as in Age of Empires).

At Bagradas (255 B.C. – a rare Carthaginian victory on land in the First Punic War), for instance, Polybius (Plb. 1.34) is clear that the onset of the elephants does not break the Roman lines – if for no other reason than the Romans were ordered quite deep (read: the usual triple Roman infantry line). Instead, the elephants disorder the Roman line. In the spaces between the elephants, the Romans slipped through, but encountered a Carthaginian phalanx still in good order advancing a safe distance behind the elephants and were cut down by the infantry, while those caught in front of the elephants were encircled and routed by the Carthaginian cavalry. What the elephants accomplished was throwing out the Roman fighting formation, leaving the Roman infantry confused and vulnerable to the other arms of the Carthaginian army.

So the value of elephants is less in the shock of their charge as in the disorder that they promote among infantry. As we’ve discussed elsewhere, heavy infantry rely on dense formations to be effective. Elephants, as a weapon-system, break up that formation, forcing infantry to scatter out of the way or separating supporting units, thus rendering the infantry vulnerable. The charge of elephants doesn’t wipe out the infantry, but it renders them vulnerable to other forces – supporting infantry, cavalry – which do.

Elephants could also be used as area denial weapons. One reading of the (admittedly somewhat poor) evidence suggests that this is how Pyrrhus of Epirus used his elephants – to great effect – against the Romans. It is sometimes argued that Pyrrhus essentially created an “articulated phalanx” using lighter infantry and elephants to cover gaps – effectively joints – in his main heavy pike phalanx line. This allowed his phalanx – normally a relatively inflexible formation – to pivot.

This area denial effect was far stronger with cavalry because of how elephants interact with horses. Horses in general – especially horses unfamiliar with elephants – are terrified of the creatures and will generally refuse to go near them. Thus at Ipsus (301 B.C.; Plut. Demetrius 29.3), Demetrius’ Macedonian cavalry is cut off from the battle by Seleucus’ elephants, essentially walled off by the refusal of the horses to advance. This effect can resolved for horses familiarized with elephants prior to battle (something Caesar did prior to the Battle of Thapsus, 46 B.C.), but the concern seems never to totally go away. I don’t think I fully endorse Peter Connolly’s judgment in Greece and Rome At War (1981) that Hellenistic armies (read: post-Alexander armies) used elephants “almost exclusively” for this purpose (elephants often seem positioned against infantry in Hellenistic battle orders), but spoiling enemy cavalry attacks this way was a core use of elephants, if not the primary one.

Bret Devereaux, “Collections: War Elephants, Part I: Battle Pachyderms”, A Collection of Unmitigated Pedantry, 2019-07-26.