Pliny the Elder reported that “elephants are scared by the smallest squeal of a pig” and that they were used as such by the Romans against Pyrrhus’s army (VIII, 1.27). A siege of Megara during the Wars of the Diadochi was reportedly broken when the Megarians poured oil on a herd of pigs, set them alight, and drove them towards the enemy’s massed war elephants. The elephants bolted in terror from the flaming squealing pigs often killing great numbers of the army the elephant was part of (Aelian, de Natura Animalium book XVI, ch. 36). A possible reason for a lack of elephants in ancient warfare could be due to this as pigs were cheap, easy to get, and supposedly effective. The Romans got the idea from the Megarans who used pigs against Gonatas.

Related concepts, whether ever actually used or not, include the concept of incendiary monkeys in China as a battlefield weapon, the use of anti-tank dogs supposedly used by the Soviet Union to combat invading German Armor at close range, and the supposed proposal of military dolphins for mine-laying as an anti-ship weapon, and as anti-diver weapons (although these usages have been denied by the US military, the use of military dolphins for mine-hunting is well documented).