Pliny the Elder reported that "elephants are scared by the smallest squeal of the hog". Aelian confirmed that elephants were frightened by squealing pigs (and rams with horns), and reported that the Romans exploited squealing pigs (and rams) to repel the war elephants of Pyrrhus in 275 BC. Procopius, in History of the Wars, records that the defenders of Edessa suspended a squealing pig from the walls to frighten away Khosrau's single siege elephant in the sixth century AD.
Historical accounts of incendiary pigs or flaming pigs were recorded by the military writer Polyaenus and by Aelian. Both writers reported that Antigonus II Gonatas' siege of Megara in 266 BC was broken when the Megarians doused some pigs with combustible pitch, crude oil or resin, 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 their own soldiers by trampling them to death.
- Lucretius, De Rerum Natura 5.1298-1349
- Pseudo-Callisthenes, "Letter to Aristole" 12
- Mayor 2005; Kistler 2007
- Pliny the Elder, "Natural History" 8.9.27
- Aelian, "On Animals" 1.38
- Procopius, "History of the Wars" 8.14.30-43
- Polyaenus, "Stratagems" 4.6.3
- Aelian, "On Animals" 16.36
Kistler, J. 2005, 2007. "War Elephants." Lincoln: University of Nebraska Press. Mayor, A. 2005, 2009. "Greek Fire, Poison Arrows, and Scorpion Bombs: Biological and Chemical Warfare in the Ancient World." NY: Overlook/Duckworth.