The elephant dreads a squealing pig.

—AELIAN, On Animals

THE PHARAOH OF EGYPT, deluded by visions of grandeur, had treated his warrior class with contempt, thinking he would never need their services. Now, he was in deep trouble. The invincible Assyrian army, led by King Sennacherib, had just invaded Egypt’s borders (in 700 BC). And now the Pharaoh’s warriors refused to fight for him. “The situation was grave,” wrote the historian Herodotus.

The great Assyrian army camped at Pelusium, in the salt flats and flax fields along the northeastern border of Egypt, poised to overtake the kingdom. The Pharaoh, who was also a priest of the god Ptah, was desperate. Regretting his pride, “not knowing what else to do,” he entered the god’s temple and bemoaned “bitterly the peril that threatened him.” The Pharaoh fell asleep in the midst of his lamentations and the god appeared in a dream. Ptah instructed the Pharaoh to forget his warriors. Instead, he said, call up all the shopkeepers, craftsmen, and market folk into an army, and boldly go out to meet Sennacherib’s troops. The god promised to send “helpers” to ensure victory. Confident now, the Pharaoh marched with his ragtag legions to Pelusium and took up a position facing the enemy host.

Night fell, and not a creature was stirring. . . . except for thousands of mice. Into the Assyrian camp crept multitudes of rodents, gnawing through all the leather quivers, shield straps, and bowstrings. The next morning the Assyrians were horrified to find they had no weapons to fight with. In antiquity, mice eating leather military gear was perceived as an omen of imminent disaster and, as already noted, hordes of rodents presaged epidemics. The terrible omen threw the men into chaos; the Assyrians abandoned camp and fled. The Egyptian ad hoc army pursued them, inflicting severe losses on Sennacherib’s men.

Herodotus heard this tale personally from the priests at the temple of Ptah, who showed him a memorial statue of the Pharaoh holding a mouse, and historians believe that a core of historical truth lies behind Herodotus’s story. Archaeologists at Nineveh have found a series of inscriptions from Sennacherib’s reign recording his invasions of Egypt and Palestine. In these, the narrative of the war breaks off abruptly, implying that some sort of unexpected calamity took place during the campaign. Putting together the various literary and archaeological clues about the incident helps clarify what probably happened.

Hebrew sources in the Old Testament also recount the sudden and ignominious defeat of Sennacherib’s army in about 700 BC, but they set the event at the gates of Jerusalem. According to 2 Kings, “an angel of the Lord smote 175,000 Assyrian soldiers”—traditional scriptural wording for plagues that destroyed the Israelites’ enemies. King Hezekiah, inside the walls of Jerusalem, was also struck by the pestilence.

Josephus, a Jewish historian writing in AD 93, added to Herodotus’s account, saying that the omen of the gnawing mice was only one reason for the hasty retreat. According to Josephus’s sources, Sennacherib had also heard that a large Ethiopian army was coming to aid the Egyptians. Then, citing Berossus, a Babylonian historian (300 BC), Josephus plainly states that “a pestilential plague killed 185,000 Assyrians” as they retreated from Egypt through Palestine.

Clearly, the Greek, Hebrew, Babylonian, and Assyrian evidence refers to a military campaign that was aborted after Sennacherib’s army was beset by disease-carrying rodents who, incidentally, ate the leather parts of their weapons at Pelusium. The bad omen and the rumor of the approaching Ethiopian army caused the Assyrians to abandon their invasion of Egypt and retreat through Palestine while the rodent-borne disease (perhaps bubonic plague or typhus) incubated in the men. As they arrived at Jerusalem, the epidemic swept through the troops, killing tens of thousands.1


In the ancient world, mice and rats were believed to be controlled by plague-bringing divinities, such as Apollo, Ptah, and Yahweh. Apollo, the god who controlled pestilence, was worshipped as “Smintheus,” killer and master of rodents. Statues of mice were set up in Apollo’s temples at Chryse and Hamaxitus near Troy, and (as noted in the discussion of plague in chapter 4), the latter temple actually maintained a horde of live white mice. Three ancient Greek sources—the natural historian Aelian and the geographers Polemon and Strabo—tell the origin of the cult of Apollo’s pestilential mice. That ancient myth has intriguing parallels to the bio-disaster that befell the Assyrian army.

Long ago, mice arrived by the tens of thousands and ruined the crops in the region around Troy. The rodents also overran the camp of an invading army from Crete, and ate all of their leather shield straps and bowstrings. With no weapons to wage war, the Cretans settled at Hamaxitus. They built the temple to Apollo, to honor the god of mice—lowly creatures who possess the power to take down entire armies.

In ancient times, writers did not differentiate among types of rodents, all of which can harbor plague, typhus, and other diseases, so when mice were mentioned in the texts, rats may have been meant. The modern chronicler of rodent-borne epidemics, William Zinsser, remarked in 1934 that long before any scientific knowledge “concerning the dangerous character of rodents as carriers of disease, mankind dreaded and pursued these animals.” The ancient Jews considered all varieties of rodents unclean, and Persian Zoroastrians so loathed rats that killing them was “a service to God.”


FIGURE 26. Rodents carry flea-borne bubonic plague and other epidemic diseases.

(Dover Pictorial Archives)

As Zinsser pointed out, “What rats can do, mice may also accomplish.” Yet, some modern scholars still take the ancient association of mice and epidemics as evidence of superstition rather than an understanding of a real source of pestilence based on observation. Apparently unaware that no distinction was made among rodents in ancient writings, and assuming that only mice were associated with disease in antiquity, some commentators assert that mice never carry bubonic plague. For example, the scholar of religion, Christopher Faraone, in his discussion of these ancient narratives in 1992, suggested that “faulty reasoning” about the “curious coincidence of swarming mice and man-killing plague” must have led the ancients to believe that vermin “cause epidemic disease.” Faraone labels this “a misunderstanding that arises from the frequency with which plague strikes close on the heels” of mouse infestations. In fact, however, science shows that pathogens are carried by the parasites (usually fleas) of rodents, which transmit the diseases to humans, and many ancient texts make it clear that periodic hordes of rodents of any sort were correctly recognized as harbingers of pestilence. The geographer Strabo remarked about infestations of vermin, “From mice pestilential diseases often ensue,” and during a rodent-borne plague that attacked the Roman army on campaign in Cantabria, Spain (first century BC), the commanders offered bounties on dead mice.

Further proof that the ancients understood the connection between rodents and epidemics can be found in the Old Testament story of the Philistines who were smote by disease after they captured the Ark of the Covenant during the war with the Israelites in the twelfth century BC. In what may be the earliest account of rodent-borne bubonic plague, the Philistine lands were afflicted by an onslaught of mice that coincided with an epidemic marked by “swellings in the Philistines’ private places.” Assuming that mice were innocent of plague, some commentators cited by Faraone identified the “swellings” as hemorrhoids and they dismiss any connection with the concurrent mouse infestation. But, as pointed out earlier, a classic sign of the Black Death is grotesquely swollen lymph glands in the groin and thighs. And 1 Samuel 5-6 clearly indicates that the Philistinesthemselves recognized the connection between rodents and the disease.2

The rodent hordes that afflicted the Philistines and averted the Assyrians’ invasion were natural disasters, since directing multitudes of infected rodents against the enemy would be nearly impossible. But the priests who prayed to their gods of pestilence for deliverance from foes by means of mice certainly intended to wage biological war, and when an enemy was routed by plague they credited the gods with the biological victory. The small creatures were considered zoological allies in war. In a striking continuity of the ancient cult of rodent allies, laboratory scientists rely on the very same “helpers” that were kept in Apollo’s temple—white mice and rats—to develop today’s germ warfare agents.

Tales like Sennacherib’s military disaster are included in this chronicle of early bio-warfare because the long observed relationship between infestations of vermin and thwarted invasions suggested the idea of praying to gods to send swarms of rodents, and probably gave people the idea of deliberately trying to turn other noxious creatures against enemies. And, in fact, as the following episodes show, a remarkable variety of creatures from the animal and insect world were recruited to achieve victory in the ancient world.


Mice were not the smallest animal allies in waging biological war. One of the biblical Ten Plagues of Egypt was an infestation of lice that “bugged” both animals and humans (lice can carry typhus). That fortuitous infestation was attributed to Yahweh, but there is plenty of evidence from ancient texts that other insects, such as stinging bees, hornets, wasps, and scorpions (venomous arthropods), were purposefully used in wartime as agents for both offense and defense. Simply by doing what came naturally, these tiny creatures could inflict damage and chaos far beyond their bodily dimensions.

Insects, with their sharp stingers, chemical poisons, and a propensity to defend and attack, have long “served as models for man to emulate in . . . the art of warfare,” commented the military historian and entomologist John Ambrose. Bees were admired in antiquity as producers of honey, but they were also respected as aggressive creatures “of exceedingly vicious disposition.” In one of the earlier examples of borrowing weapons from nature’s armory, we saw how a relatively primitive tribe in Asia Minor decimated Pompey’s Roman army by setting out toxic honeycombs. As Pliny noted, the baneful honey was the bees’ defensive weapon against human greed. But the honeybees themselves—and wasps and hornets (the largest species of wasps)—were armed with stingers. Swarms had been known to invade cities, forcing entire populations to relocate. Such a disaster had befallen the residents of Phaselis (central Turkey), and the people of Rhaucus, in Crete, had to abandon their city when copper-colored killer bees from Mount Ida arrived in great swarms.

Why not hurl entire hives filled with enraged, venomous insects at an enemy? The painful stings would send any army into wild confusion and retreat, and massive numbers of stings could be fatal. According to folk belief cited by Pliny, it took only twenty-seven hornet stings to kill a man (in fact, even one sting can cause death in individuals who are sensitive to the venom).

Beehive bombs were probably among the first projectile weapons and Edward Neufeld, a scholar of Mesopotamian history, surmises that hornets’ nests were lobbed at enemies hiding in caves as early as Neolithic times. Bees have figured in warfare in different cultures of many eras. The sacred text of the Maya in Central America, the Popol Vuh, for example, describes an ingenious bee boobytrap used to repel besiegers: dummy warriors outfitted in cloaks, spears, and shields were posted along the walls of the citadel. War bonnets were placed on the heads, which were actually large gourds filled with bees, wasps, and flies. As the assailants scaled the walls, the gourds were smashed. The furious insects honed in on the warriors, who were soon “dazed by the yellow jackets and wasps [and were sent] stumbling and falling down the mountainside.”3

FIGURE 27. Wasp nests and beehives were hurled at enemies from Neolithic times onward.

(Dover Pictorial Archives)


Were hornets and other venomous insects marshaled to scourge the Israelites’ foes? Neufeld has written that in biblical times insects were “important military agents in tactics of ambush,” guerrilla raids, and flushing out primitive strongholds. He also noted that ancient Hebrew and Arab sources refer to hordes of unidentified flying insects that were summoned to attack the enemies’ eyes with “acrid poison fluids,” blinding or killing them. As Neufeld pointed out, these could belong to any of the dozens of species of noxious insects in the Near East. He suggested that the gadfly, or “eye fly,” may have been the unknown insect that ejected blinding poison. But thinking back to poisonous insect “droppings” of India described by Aelian (chapter 2), is it possible that these Near Eastern stories were about infestations of Paederus beetles? The beetles excrete the virulent poison pederin, a fluid that causes suppurating sores and blindness, and in the bloodstream the effect is as deadly as cobra venom. Plagues of Paederus beetles period-ically afflict populations in Africa and in the Mideast, but it is difficult to see how the swarms could ever have been directed effectively in a military campaign.


FIGURE 28. A swarm of bees or hornets attacking men. Amphora from Vulci, about 550 BC.

(© The British Museum)

Some biblical passages cited by Neufeld do seem to suggest a planned military use of stinging insects. Exodus states that hornets were “sent ahead” of the Israelites to drive out the Canaanites, Hittites, and other enemies, and in Deuteronomy, hornets supplemented ordinary weapons against the Canaanites. In Joshua, hornets, in conjunction with swords or bows, drove out the Amorites. Proposing that these biblical narratives describe “massive assaults” with hornets’ nests, “plotted and contrived deliberately,” rather than spontaneous swarming insect behavior, Neufeld argued that the “texts clearly reflect an early form of biological warfare.” Even the “crudest forms” of such warfare, simply throwing beehive bombs by hand, could rout an enemy hiding in caves with stings and panic.

Deploying stinging insects involved hazards for those who used them in war. The traditional practice of the Tiv people of Nigeria shows one clever method of directing bees at the enemy. The Tiv kept their bees in special large horns, which also contained a toxic powder. The poison dust was said to strengthen the bees’ venom, but it is possible that it was a drug to calm the bees in the horn. In the heat of battle, the bees were released from the horns toward the enemy. It was not recorded how the Tiv avoided stings themselves, but it seems that the shape and length of the horns effectively propelled the swarm toward the enemy ranks.

Tossing beehive bombs at enemies also involved the potential for “blow-back.” Stinging insects had to be “kept peacefully in their nests before the ammunition was used against the foe; the danger of premature explosion must have been considerable.” To reduce “the chances of backfire,” noted Neufeld, buzzing bombs had to be “hurled carefully at the enemy, wherein the bursting nest would release hundreds of very nervous hornets on the target.” He suggests that hornets’ nests may have been plugged with mud and transported in sacks, baskets, and pots, or perhaps bees were persuaded to colonize special containers.

One precaution against misdirected stings was smoke, which was recognized as a tranquilizer of bees very early in antiquity. Another method was to set up hives with trip wires along the enemy’s route, a method used by both sides in Europe in World War I. Obviously, a great deal of skill and a variety of releasing devices were required for the entire operation, and it is possible that beekeeping shamans were involved in stunning the hornets with smoke or toxic dust, and in planning the attacks.4

There is historical evidence that the old strategy of hurling hives of stinging missiles at enemies continued to flourish even as more sophisticated methods of siege-craft were developed. Catapults, for example, were a very effective delivery system for launching biological weapons of all sorts—including hornets’ nests—while avoiding collateral damage. In fact, catapulting beehives at enemy troops became a favorite Roman tactic. In his survey of the use of bugs in battle from biblical times to the Vietnam War, John Ambrose even suggested that the Romans’ extensive use of bees in warfare may partly account for the recorded decline in number of hives in the late Roman Empire. Ambrose also pointed out that heaving hives continued in popularity in later times: for example, Henry I’s catapults lobbed beehives at the Duke of Lorraine’s army in the eleventh century, a tactic used again in 1289 by the Hungarians against the Turks. More recently, in the 1960s, the Vietcong set boobytraps with giant, ferocious Asian honeybees (Apis dorsata) against American soldiers. In retaliation, says Ambrose, the Pentagon began developing its own top-secret bee weapon to use against the Vietcong, based on the bees’ alarm chemical, a pheromone that marks victims for a swarming attack. Such weapons are, in 2003, still in the development stage.5

As the ancient Maya and many others have recognized, bees could provide a very effective defense, too. Defenders of the medieval castle on the Aegean island of Astipalaia, for example, fended off pirate attacks by dropping their beehives from the parapets. In Germany in 1642, during the Thirty Years’ War, attacking Swedish knights were repulsed with beehive bombs. Armor protected the knights, but the clouds of stinging bees drove their horses crazy. In the same era, the village of Beyenburg (Bee-town) was named in honor of some quick-thinking nuns who overturned the convent hives to repel marauding soldiers. When Mussolini invaded Ethiopia in 1935-36, Italian planes sprayed a fog of mustard gas that devastated civilians and the landscape. The Ethiopians’ only recourse was to drop beehives from ridges down onto the Italian tanks, terrorizing the drivers and causing crashes.

Stinging insects certainly helped defend forts in antiquity. In the fourth century BC, Aeneas the Tactician, in his book “How to Survive under Siege,” advised “besieged people to release wasps and bees into tunnels being dug under their walls, in order to plague the attackers.” This same tactic was employed against the Romans in 72 BC by King Mithridates in Pontus, according to Appian of Alexandria (a historian of the second century AD). Appian relates that Licinius Lucullus (one of several Roman commanders who failed to capture the wily king) laid siege to Mithridates’ strongholds at Amisus on the Black Sea, and at Eupatoria and Themiscrya. Lucullus’s sappers excavated tunnels under the citadels, passageways so capacious that several subterranean battles were fought in them. But Mithridates’ allies routed the Romans by drilling holes that intersected the tunnels and releasing not only swarms of angry bees, but also bears and other rampaging wild beasts.6


In AD 198-99, the emperor Septimius Severus began the Second Parthian War, in one of several Roman bids to control Mesopotamia. He failed in two separate attempts to capture the remote desert stronghold of Hatra, a city that derived great riches from its control of the caravan routes. Hatra’s impressive remains, south of Mosul, Iraq, reveal the ruins of an enormous double-walled fortress with ninety large towers, 163 small towers, and a moat. The city was located at the top of a precipitous ridge, and surrounded by barren desert.

Holed up inside their fortified city, King Barsamia and the citizens of Hatra prepared strong defense plans as the Roman legions advanced over the desert. One of their defenses was biological. Anticipating by seventeen hundred years the bombs of fragile porcelain filled with noxious insects that the Japanese dropped on China in World War II, the Hatreni filled clay-pot bombs with “poisonous insects” and sealed them up, ready to hurl down at the attackers.7

Herodian, a historian from Antioch (Syria), who recounted the story, did not specifically identify the venomous creatures, but simply referred to them as “poisonous flying insects.” What sort of insects would have been collected by the Hatreni? In the “wretched,” waterless wilderness stretching for miles in every direction around Hatra, nothing grew but dragonwort and wormwood; there were no bees, except for an occasional solitary ground bee. Scorpions, on the other hand, were extremely abundant. The stinging creatures were sacred to the local goddess Ishhara and scorpion motifs abound in Mesopotamian mythology.

In the deserts surrounding Hatra, deadly scorpions lurked “beneath every stone and clod of dirt,” wrote the natural historian Aelian. They were so numerous that to make the land between Susa to Media safe for travel, Persian kings routinely ordered scorpion hunts, bestowing bounties for the most killed. Scorpions, declared Pliny, “are a horrible plague, poisonous like snakes, except that they inflict a worse torture by dispatching their victim with a lingering death lasting three days.” The sting is intensely painful, followed by great agitation, sweating, thirst, muscle spasms, convulsions, swollen genitals, slow pulse, irregular breathing, and death.

Everyone “detests scorpions,” agreed Aelian. The fear factor was put to symbolic military use among the ancient Greeks, who painted scorpion (and snake) emblems on their shields to frighten foes, and by the early first century AD, the scorpion had been taken up as the official emblem of the dreaded Roman Praetorian Guard, the personal troops of the emperors. It’s no coincidence that modern U.S. military weapons carry names like “scorpion” and “stinger,” “hornet,” and “cobra” to instill confidence among the troops that man them and to inspire fear among the enemy.


FIGURE 29. Scorpions abound in the desert around Hatra, and they were used as live ammunition against Roman besiegers.

(Dover Pictorial Archives)

According to Aelian, the sting of some scorpion species killed instantly, and in the Sinai peninsula, gigantic scorpions preyed on lizards and cobras. Anyone who even “treads on scorpion droppings develops ulcers of the foot.” Eleven types of scorpion were known in antiquity: white, red, smoky, black, green, pot-bellied, crab-like, fiery red-orange, those with a double sting, those with seven segments, and those with wings. Most of these species have been identified by entomologists, but others may have been venomous insects mistaken for scorpions.

True scorpions lack wings, and Herodian referred to flying, stinging insects in his account. But ancient authors consistently referred to winged varieties of scorpions and winged scorpions are also depicted in ancient artifacts. The natural historian Pliny explained the error. Scorpions are given the power of flight by very strong desert winds, he said, and when they are airborne, the scorpions extend their legs, which makes them appear to have membraned wings.

The modern commentator on Herodian, C. Whittaker, dismissed Herodian’s account of clay pots filled with scorpions as a tall tale based on a special double-firing ballistic catapult that was called the Scorpion. But the abundance of scorpions in the desert, and the many other historical reports of hurling hornets’ nests and earthenware pots filled with noxious creatures in ancient military engagements make Herodian’s account quite plausible. In fact, heaving scorpions by the basketful at attackers was specifically recommended by Leo VI (AD 862-912), in his famous military Tacticshandbook.

The Hatreni would have gathered the venomous insects in advance and, to avoid getting stung while preparing their live bio-ammunition, they would have followed several safety procedures. Aelian told of the “innumerable devices contrived for self-protection” against the giant Egyptian scorpions (seven inches long) and the multitudes of them in North Africa, where people “devise endless schemes to counter scorpions.” Wearing high boots and sleeping in raised beds with each bedpost in a basin of water were just two common defenses.

Scorpion stings were most deadly in the morning, declared Pliny, “before the insects have wasted any of their poison through accidental strikes.” The Hatreni may have teased the irascible arthropods into wasting stings before they placed them in the pots. Aelian pointed out that the stinger was a very slender hollow core, so one could temporarily block the tiny opening by very carefully spitting on the tip of the stinger. Or, one could sprinkle scorpions with deadly aconite (monkshood) powder, which was said to cause the creatures to shrivel up temporarily. They could be revived with poisonous white hellebore, once they were inside the earthenware containers.

It’s possible that other venomous flying insects, such as assassin bugs, were called scorpions in antiquity. Assassin bugs (cone-nose bugs, Reduviidae family) were notoriously used by rulers in Central Asia for torturing prisoners. These predatory, bloodsucking insects cling tenaciously to a victim and push their sharp beaks into the flesh, injecting a lethal nerve poison that liquefies tissues. The bite can be extremely painful. Assassin bugs do have wings, and Herodian’s description of the effects of the “poisonous flying creatures” fits these insects’ clinging, piercing attack: As Severus’s men attempted to ascend the walls, the clay pots were rained down on them. “The insects fell into the Romans’ eyes and the exposed parts of their bodies,” wrote Herodian, “Digging in before they were noticed, they bit and stung the soldiers, causing severe injuries.”

Probably the best conclusion is that the earthenware bombs contained a potpourri of scorpions, assassin bugs, wasps, pederin beetles, and other venomous insects from the desert around Hatra.

Military historians are perplexed over what caused Severus to give up his siege of Hatra after only twenty days, just as he had successfully breached the city walls and victory was within reach. Roman sieges were usually grueling ordeals, and they were expected to last several months or even years but they were ultimately successful. So, what could have caused Severus to back off? Citing the “insalubrious desert,” mutinous troops, poor planning and disputes over plunder, a possible secret treaty, or other unknown factors, modern scholars seem to be unable to accept the ancient historians’ clear indications that it was the brute effectiveness of Hatra’s defensive biological and chemical weapons that overcame Roman morale, manpower, and siege machines.

Herodian gives a vivid account of the violent battle, in which nearly every siege technique was tried. He makes it clear that the scorpion bombs were just one of many types of ammunition fired at the Romans. In the scorching desert sun, a great many legionaries had succumbed to the heat and unhealthy climate even before the battle, but the Romans sent their full forces and manned every kind of siege machine. The Hatreni “vigorously defended themselves” with their double-shot catapults, “firing down missiles and stones.” Dio Cassius adds that the Hatreni also poured burning naphtha on Severus’s army, which completely destroyed his siege engines and enveloped his men with unquenchable petroleum-fed flames.

The last straw must have come when the defenders began firing the jars full of hideous bugs down on Severus’s soldiers as they assaulted the walls. The terror effect would be quite impressive, no matter how many men were actually stung. Herodian states that these combined defense tactics caused Severus to withdraw “for fear his entire army would be destroyed.” And the desert fortress of Hatra remained independent in “splendid isolation” until AD 241, when it was reduced to ruins by Iranian Sasanids.8


Harking back to ancient deployments of stinging insects, Pentagon experts not only investigated ways of using bees to attack the enemy in Vietnam, but also tested the ability of assassin bugs (there are thousands of species around the world) to hone in on prey at long distances. During the Vietnam War, the Army carried out tests using assassin bugs in special capsules to track down the Vietcong in the jungle. The predatory bugs reportedly detected humans from a distance equivalent to two city blocks and emitted a “yowling” sound that was amplified to audible range. It is not known whether the assassin bug tracking device was ever actually used in the jungle.

The ancient practice of enlisting insects as weapons has been taken to new levels in the U.S. government’s most advanced research. Since 1998, the Pentagon has sponsored experiments in “Controlled Biological Systems” to create sophisticated war technologies based on entomology and zoology. The research is overseen by the Defense Advanced Research Projects Agency (DARPA), the central research and development unit of the Defense Department. The mission is to exploit the natural traits of what they call “Vivisystems,” living creatures from insects to intelligent animals, in order to “turn them into war-fighting technologies.” Just as the ancients learned to use the natural instincts of bees in waging war, scientists are studying insects whose attributes might be valuable for military purposes. For example, DARPA-funded laboratories are training honeybees to detect minute amounts of substances that indicate the presence of biochemical or explosive agents. The hope is to deploy the hypersensitive insects as spies and sentinels in biochemical warfare.

We have come a long way from praying to plague gods to send mice and lobbing hornets’ nests at foes—and yet the Defense Department’s sophisticated insect research still relies on the timeless principle of exploiting bees’ instincts. But living insects have disadvantages: for example, bees sting indiscriminately and they won’t work when cold, at night, or in storms. Accordingly, DARPA scientists are improving on mere Vivisystems by designing “Hybrid Biosystems” and “Biomimetics.” With brain-computer interface technology, they can integrate living and nonliving components, for example, by reengineering bee neurology or attaching real bee antennae to a cyborg bee.

In antiquity, biological strategies were often justified in self-defense and, as noted earlier, often modern treaties allow biochemical weapon research for defense, which can serve as a cover for covertly developing biochemical agents with first-strike capabilities. The tendency to justify biological armaments “for defense only” is evident in the public explanations of DARPA’s Vivisystems mission. One ambiguous sentence in the DARPA “Objectives” statement of 2003, for example, remarks that “other applications [of insect agents] might involve controlling the distribution of pest organisms to improve operational environments for troops,” while the next sentence asserts that “all aspects of the program are for defensive purposes only.”

Scientists stress the peaceful applications of their DARPA-funded research, but the military applications are obvious. The most recent Hybrid Biosystem creations, remote-controlled rats, are promoted in the media as “search and rescue” agents, but the project scientists admit that the cyber-rat would also be “an ideal delivery system for biological weapons.” What nature (and the god Ptah) brought to Sennacherib’s Assyrian army in Egypt back in 700 BC—a rodent-borne plague—could now be delivered by remote-control. The DARPA scientists have also successfully wired monkey’s brains to control machines. Transforming animals into living war machines represents a giant step in the militarization of nature. And the use of intelligent animals in war has a very ancient history.9


In antiquity, mice were inadvertent allies in repulsing attackers, and even smaller allies were the stinging insects whose natural aggressive instincts could be directed against foes. But larger creatures, such as the ferocious bears sent against the Roman besiegers in Pontus in 72 BC, could also be drafted for war duty.

Hannibal’s masterful use of animals during his invasion of Italy in 218 BC is an excellent example of how creatures could be used for war. The well-known feat of Hannibal’s war elephants crossing the snowy Alps was only the beginning, for the Carthaginian general had many ad hoc animal tricks. For example, when he seemed to be trapped in a narrow valley guarded by the Romans, Hannibal terrified the enemy into wild flight by assembling herds of cattle and affixing burning torches to their horns. He made a safe getaway that night, by driving the herd before his army toward the Romans.

Four different historians related another creative zoological ploy thought up by Hannibal during a decisive naval battle against King Eumenes of Pergamum (Asia Minor) sometime between 190 and 184 BC. Hannibal and his allies were far outnumbered in ships. Therefore, explains the Roman historian Cornelius Nepos, “it was necessary for him to resort to a ruse, since he was unequal to his opponent in arms.” Hannibal sent his men ashore to “capture the greatest possible number of venomous snakes” and stuff them into earthenware jars. When they had amassed a great many of these, he prepared his marines for the battle. The biological secret weapon boosted the confidence of the outnumbered men, reports Nepos. When the clash came and Eumenes’ ships bore down on Hannibal’s fleet, the marines let fly the jars, catapulting them onto the enemy decks.

The enemy’s first reaction to the smashing pottery was derisive laughter. But as soon as they realized their decks were seething with poisonous snakes, it was Hannibal’s turn for mirth, as the horrified sailors leaped about trying to avoid the vipers. Eumenes’ navy was overcome and it may have been this incident that led Eumenes to make his famous remark that an honorable general should eschew victory by underhanded means that he would not like to have turned against himself.

Hannibal’s idea was to terrorize Eumenes’ crew so that they were unable to fight and similar ideas have occurred to commanders in other times and places. For example, in Afghanistan in about AD 1000, during the siege of Sistan, Mahmud of Ahazna ordered his men to catapult sacks of serpents into the stronghold to terrify the defenders of the fort.10

Animals could also be used to give the enemy an illusion of vast numbers of attackers, a ploy that was advised by Polyaenus and other ancient strategists. Alexander the Great, for one, resorted to such a trick in Persia, tying branches to the tails of sheep to raise clouds of dust, which the Persians took as the sign of a massive army. He also tied torches to the sheep at night, so that the whole plain looked to be on fire. Alexander’s successor, Ptolemy, did the same thing in Egypt in 321 BC, when he attacked Perdiccas, binding loads of brush to herds of pigs, cattle, and other domestic animals to raise dust as he approached with his cavalry. Perdiccas, imagining a very great cavalry was galloping toward him, fled and took heavy losses.

Much earlier, in the sixth century BC, the Persian king Cambyses lay siege to Pelusium, which had remained the same entry point for invaders of Egypt since Sennacherib’s mouse-borne disaster there in the eighth century BC. This time, the Egyptian defense was very well-organized, holding off the Persians with batteries of artillery that shot stones, bolts, and fire. Cambyses responded by placing a unique zoological shield before his ranks: a phalanx of yowling cats, bleating sheep, barking dogs, and silent ibexes. All these animals were worshipped by the Egyptians, and just as Cambyses hoped, the warriors halted their fire to avoid harming any sacred creatures. Pelusium fell and the Persians conquered Egypt.11

All the creatures dispatched against the enemy discussed so far have been involuntary zoological allies: from Chrysame’s poisoned bull (in the previous chapter), swarms of mice, and innocent sheep dragging branches, to venomous creatures whose aggressive nature leads them to attack human targets. But, unlike hordes of wasps or rodents whose instincts might work to the advantage of one side in military contexts, large, intelligent animals could be specially prepared for battle. Almost every army in antiquity maintained baggage animals (mules, oxen, donkeys, camels) and used dogs for sentry duty, and some large animals were trained to actively participate in war: horses and camels were cavalry mounts, while dogs and war elephants could be used to attack the enemy.


Ever since dogs became man’s best friends they have served as sentinels to warn of intruders. Their acute senses and their loyalty, vigilance, speed, and intelligence make them valuable for military purposes. To guard the citadel of Acrocorinth against Philip of Macedon in 243 BC, for instance, the great guerrilla general Aratos set out fifty dogs, while an inscription from the small Greek city of Teos (on the Turkish coast) records that three dogs were to be purchased for sentinel duty at the garrison fort. In the fourth century BC, Aeneas the Tactician referred frequently to dogs as sentries and messengers in wartime, but he also warned that their instinct to bark could backfire.

Dogs also participated in combat. Perhaps the earliest evidence of dogs in war is an Assyrian stone relief from about 600 BC found at Birs Nimrud (Iraq), depicting a warrior carrying a shield and leading a large, armored mastiff. According to Pliny, the king of the Garamantes of Africa had two hundred trained war dogs “that did battle with those who resisted him.” The cities of Colophon and Castabala in Asia Minor also maintained troops of war dogs that fought ferociously in the front ranks. These canines were their most loyal allies, joked Pliny, “for they never even required pay.” The Hyrcanians of the Caspian Sea and the Magnesians (a mountain tribe of northeastern Greece) were also feared for the large hounds with spiked collars that accompanied them on the battlefield (by the Middle Ages, war dogs would sport full coats of mail). “These allies were an advantage and great help to them,” remarked Aelian, although he did not give any gory details.

Just as using poison arrows (originally intended for hunting) to kill humans tended to raise the hackles of classical Greeks and Romans, siccing hunting dogs on human quarry might have seemed brutal and inhumane to many. But Polyaenus, the strategist who advised the Roman emperors on how to beat the barbarian Parthians in the second century AD, recounted with approval how the “monstrous and bestial Cimmerians” were driven out of Asia Minor in the sixth century BC by the vicious hounds of King Alyattes of Lydia (west-central Turkey). The Cimmerians of the steppes had been driven west by the Scythians and subsequently invaded Lydia. King Alyattes set his “strongest dogs upon the barbarians as if they were wild animals”—which is exactly how Polyaenus characterized the invaders. The king’s war dogs, he wrote, “killed many and forced the rest to flee shamefully.”


FIGURE 30. Assyrian war dog on a sculptural relief from Birs Nimrud, about 600 BC.

At the glorious Battle of Marathon in 490 BC, when the Athenians and their allies defeated the Persian army to the tune of 6,400 dead (only 192 Greeks perished), one Athenian dog received honors “for the dangers it faced,” along with the greatest human heroes of the war. The dog had served as a “fellow-soldier in the battle,” wrote Aelian, and it was featured in the famous paintings of the victory in Athens.

Dogs continued to participate in battles up to modern times, and the classical vignette of the trusty war-dog hero at ancient Marathon could serve as the original K-9 Corps tale. Many dogs went to war in World War I, but war-dog training in the U.S. armed forces began on a large scale during World War II. By 1945, nearly ten thousand dogs served in K-9 War Dog platoons in Europe and the Pacific. Dogs also worked as sentries, scouts, and pack animals in the Korean, Vietnam, and Gulf wars.


FIGURE 31. The heroic Athenian war dog at the Battle of Marathon (490 BC) during the defeat of the Persians.

Canines and other mammals fall into the Defense Department’s category of “Controlled Biological Systems” for waging war with the help of animals. The zoological scope of the program far exceeds Cambyses’ military menagerie in the Persians’ front ranks, used to stop the Egyptian artillery 2,500 years ago. Since the Vietnam War, the Pentagon has funded the classified training and deployment of numerous species of mammals, including dogs, skunks, rats, monkeys, sea lions, dolphins, and whales. For example, in the 1980s U.S. Navy-trained dolphins were sent to the Persian Gulf to patrol the harbor for mines and to escort Kuwaiti oil tankers. In 2003, sea lions, trained to pursue and capture enemy divers with leg clamps, were deployed to the Gulf. The Navy claims that no mammals have ever been trained to kill humans, in keeping with the ancient justification of biological weapons for defense only.12


The Greeks were astounded when they first encountered trained war elephants in action, at the battle on the Hydapses River, where Alexander the Great defeated King Porus in India, in 326 BC. The soldiers were able to rally their spirits and prepared to fight the strange, imposing beasts, but Alexander quickly realized that his cavalry horses were terrified and would not face Porus’s two hundred elephants. He found ways to outmaneuver the elephants with his infantry, by boxing the elephants in and ordering his men to aim their long javelins to kill the mahouts. Hemmed in and without their drivers, Porus’s elephants ran amok and trampled many of their own men. Alexander captured eighty of Porus’s elephants and, seeing how useful they could be, he obtained one hundred more in subsequent campaigns in India.

According to legends that grew up around the figure of Alexander, he devised another brilliant plan to deflect the ranks of living tanks. As they story goes, Alexander piled up all the bronze statues and armor that he had taken as booty during his conquests so far and heated them over a fire until they were red-hot. (In reality, the Greeks brought very little booty with them over the Khyber Pass.) Then he set up the statues and shields like a wall in front of the elephants. When Porus sent forth his elephants, they made straight for the heated statues, taking them for enemy soldiers. As the beasts smashed into the statues, “their muzzles were badly burnt” and they refused to continue the attack.


FIGURE 32. Indian war elephant, with tower of warriors and mahout, detail from a coin.

Alexander’s Hellenistic successors, the Seleucids and Ptolemies, made heavy use of war elephants, which became the glamour weapon of the Hellenistic era. The elephants were carefully trained from birth by the traditional suppliers in India and they were very effective, especially against men and horses who had never set eyes on such creatures before. Elephants could also tear down wooden fortifications. Clanging bells were hung on the massive beasts; they were fitted with coats of armor and iron tusk covers, and carried crenellated “castles” with archers on top. An elephant could charge at fifteen miles per hour (but at that momentum, it had difficulty coming to a halt). The stampeding animals could plow through tight phalanxes of men, crushing them or causing them to scatter to avoid being trampled.

The Romans were first introduced to war elephants when Pyrrhus of Epirus invaded Italy in 280 BC with Indian war elephants. The “bulk and uncommon appearance” of Pyrrhus’s twenty pachyderms, each one carrying a tower with one or two men with bows and javelins, undid the Romans, and their terrified cavalry horses refused to face the beasts. In the panic, many Roman soldiers were impaled by the elephants’ tusks and crushed under their feet. Pyrrhus won, but with such excessive losses of his own men that he remarked that another victory would totally ruin him—thus the phrase “Pyrrhic victory.” By 275 BC, Pyrrhus had lost many of his elephants and two-thirds of his original forces.


FIGURE 33. War elephants could cause chaos in enemy ranks, but sometimes trampled their own men in the melee.

Hannibal’s elephants crossed the Alps in the winter of 218 BC, during the Carthaginian’s invasion of Italy. The North African forest elephants were smaller than Indian elephants and carried only a single mahout—the beasts themselves were the weapons. In the alpine winter, however, all but one of the Carthaginian’s thirty seven elephants died in the snow. He sent for more in 215 BC, but by then the Romans and their horses were not as terrified by the sheer sight of elephant phalanxes.

In the third century BC, the Hellenistic Seleucid king Antiochus routed the Galatians, Gauls who had invaded Anatolia. In the famous non-battle, the Galatians were overwhelmed by the bizarre sight and loud clamor of Antiochus’s sixteen trumpeting elephants with gleaming tusks advancing on the distant plain. The Galatian cavalry horses reared and wheeled in fright, and the foot soldiers were trampled under their hooves. In the first century BC, the Britanni surrendered to the Romans at the sight of just one enormous elephant in gleaming armor. One of the advantages of biological weapons is the element of surprise and horror that can cause the challenged to capitulate without a fight—and elephants were no exception.

The war elephant could intimidate the enemy, but the cumbersome animal was so unpredictable that after a time it came to be regarded as a liability rather than an asset. The problems of friendly fire and collateral damage were serious. Apparently, drugs were frequently administered before battle to make the beasts more aggressive, and if the elephant’s mahout was killed, or the elephant was badly wounded or disoriented by something untoward, or in rut, the crazed behemoth would crash out of control, squashing its own men. Contemplating such bloody disasters with elephants in the first century BC, the Roman philosopher Lucretius surmised that perhaps other wild animals, such as lions, were “once enlisted in the service of war” in very early times, with similarly catastrophic results. The “experiment of launching savage boars against the enemy failed,” he speculated, as did “advance guards of lions on leashes.” The brute beasts, “enflamed by the gory carnage of battle,” must have slashed their own masters with tusks, talons, and teeth, “just as in our own times war elephants sometimes stampede over their own associates.”

Safety procedures were developed to deactivate rampaging war elephants. Each mahout had a sharp chisel blade bound to his wrist, so that if his wounded elephant suddenly reversed direction he could drive it into the beast’s neck with a mallet, killing it instantly. This expedient was said to have been invented by the Carthaginian general Hasdrubal.

“Elephants, like prudent men, avoid anything that is harmful,” noted Aelian. Unlike insects, intelligent creatures such as dogs, horses, and elephants are subject to fear and rational instincts for self-preservation, which creates disadvantages and boomerang effects. It’s an old problem that continued in modern times: in the Thirty Years’ War (1618-48), the Swedish warhorses fled from swarms of stinging bees unloosed by the enemy; and during World War II, British scout dogs, unnerved by heavy artillery fire, lost their sense of direction and failed to smell out the enemy.

In antiquity, guard dogs barked at the wrong time, and cavalry horses were spooked by elephants, while wounded war elephants panicked and crushed their own armies. Horses stampeded at the exotic scent of camels—who, for their part, “possessed an innate hatred for horses.” What if incompatible species, say camels and horses, actually met on the battlefield? Pandemonium ensued—and that could work to a clever general’s advantage.13


Some animal species instinctively loathed other species or panicked at the presence of unfamiliar beasts, and an unexpected confrontation of incompatible or hostile animals could cause violent confusion during a skirmish. Drafting various members of the animal kingdom into human warfare, in order to take advantage of the antipathy between, say, horses and elephants, constituted a biological strategy, in the sense of manipulating natural forces against the enemy. These ingenious schemes had devastating consequences for an unprepared army, but animal ruses like these aroused few qualms about fairness in antiquity. An intelligent commander might anticipate, or even prepare for ploys based on the natural anagonism among animals. Nevertheless, a leader who understood which kinds of creatures would immediately send the enemy’s trained war animals into a frenzy could often gain the upper hand. When inter-species conflict suddenly erupted during a military engagement, some spectacular reverses of fortune resulted.

In 546 BC, for instance, King Cyrus of Persia was about to meet the formidable cavalry of King Croesus, the son of Alyattes, in Lydia. At the sight of the ranks of skilled Lydian cavalrymen armed with long spears massing on the plain, however, the Persian king’s confidence plummeted. Cyrus was sure his cavalry would be bested. Herodotus tells us that one of Cyrus’s advisors came up with an emergency plan based on his knowledge of animal antipathy. Knowing that a horse naturally “shuns the sight and the scent of a camel,” the Persians unloaded their baggage train of camels, and placed them in the front line, keeping their own camel-tolerant cavalry in the rear. Before the battle even began, Croesus’s proud cavalry was “rendered useless.” At the first sight and scent of the dromedaries, the horses turned and galloped away, snorting in disgust and fear. Many of the Lydian foot-soldiers were trampled in the melee. Ever since that battle, most ancient armies kept a few camels among their horses, to acquaint them with their rank odor.

A couple of generations later, King Darius of Persia was galled and frustrated by the hit-and-run guerrilla tactics of the mounted Scythian archers, who made raids and then melted away, refusing to meet the Persians face to face. Darius knew that the Scythian cavalry was superior to his own, but felt certain that he could beat the nomads with his infantry, if only he could force them to stay and fight. Herodotus reports that the Persians enjoyed only one small advantage over the Scythians in skirmishes. Donkeys were completely unknown in Scythia, and during the battles the harsh hee-hawing of these Persian pack animals “so upset the nomads’ horses . . . that they would constantly stop short, pricking up their ears in consternation.” Darius, exasperated and running short on supplies, finally used his asses to cover his ignominious retreat from Scythia. As he slunk away by night, he left behind his donkeys, whose braying tricked the nomads into thinking the Persians were still there.


As noted earlier, the sight, sound, and odor of elephants threw untrained horses into chaos, and ancient military history records several disastrous defeats caused by horses (and men) turning tail at the novel appearance of elephants. The most famous example occurred in Britain in 55 BC, when the Britannis’ chariot-horses fled at the sight of Julius Caesar’s monstrous war elephant covered in iron scales and clanging bells emerging from a river with a tower of archers balanced on its back.

By the Hellenistic period, when war elephants became all the rage for the Ptolemies and Seleucids, commanders tried to obtain at least some elephants in order to condition their cavalry horses. In the second century BC, however, Perseus, a son of the Macedonian King Philip V, came up with an alternative plan to prepare his cavalry for an invasion by Romans who were bringing African and Indian war elephants. Perseus had artisans build and paint wooden models to resemble elephants, so that their size and shape would not intimidate his horses. Then he had pipers hide inside the huge mock-ups and, as these were rolled toward the horses, the pipers played “harsh, sharp trumpeting sounds” on their pipes. By this means, the Macedonian horses “learned to disdain the sight and sound of elephants.”14

Over time, elephants became less of a novelty and ever more creative gambits were discovered to neutralize them in battle. Alexander the Great was the first to discover a surefire way to repulse elephants —by making use of elephants’ natural aversion to pigs. Elephants were admired in antiquity as intelligent and tasteful lovers of all things beautiful; they appreciated perfumes, lovely women, flowers, music, and so on. By the same token, these wrinkled, gray, lumbering beasts, capable of ear-piercing trumpeting, abhorred ugly things and were especially agitated by discordant sounds. Their highly developed aesthetic sensibilities could be turned against them in battle.

Legend has it that Alexander the Great learned this important bit of local knowledge from King Porus, who became Alexander’s ally after Porus’s defeat in 326 BC. Alexander had a chance to test the repellent effect of swine on elephants in India when his scout reported that about one thousand wild elephants were approaching the camp from the forest. On Porus’s advice, Alexander ordered his Thracian horsemen to take some pigs and trumpets and ride out to meet the elephant herd. Porus assured Alexander that if the pigs could be caused to keep squealing they could overcome the elephants. Indeed, as soon as the great beasts heard the harsh sound of the pigs combined with the Thracian trumpets, they fled back into the forest.

The Romans discovered a similar technique in 280-275 BC, when Pyrrhus was wearily marching the surviving twelve of his original twenty war elephants across Italy. The Romans noticed that the pachyderms were unnerved by the sight of rams with horns and that they could not abide the high-pitched squeals of swine. Aelian says that both of these domestic animals were used to deflect the elephants of Pyrrhus, perhaps helping to account for his heavy losses of men and beasts.

In antiquity, the use of special sensory effects—sound, smell, and sight—to terrify war animals—or human foes—was considered an unconventional but fair tactic. For example, the Roman historian Tacitus described the psychological effects of the baritus, the hair-raising war-cry of the Germanic tribes intended to demoralize the enemy. The chanting warriors produced a “harsh, intermittent roar,” which rose to a reverberating crescendo as they held their shields in front of their mouths to amplify the thunderous sound. Ways of producing “horrible sounds,” optical illusions, and explosive noises to disorient and frighten enemies were also described in ancient Indian and Chinese war manuals. As we’ve seen, assaults on sensitivity to odors—the stink of unfamiliar or hated species—could send an enemy’s war animals into chaos, but offensive smells could be directed against humans as well. Strabo, for instance, described the overpowering reek of the poison arrows of the Soanes of Colchis as being injurious to victims even if they were not wounded.


FIGURE 34. A squealing pig was an effective weapon against war elephants. Red-figure kylix, about 490 BC, detail.

(University of Pennsylvania Museum)

The ancient experiments with unbearable noise and odors used against enemies and their war animals have been revived with modern research into “non-lethal” weapons directed against humans. Military scientists have created malordorants (repulsive smells to trigger incapacitating nausea) and very loud, low-frequency sounds, like the deafening rock music that was blasted day and night by U.S. Loudspeaker Teams during the siege of Panamanian general Manuel Noriega in 1989, and again, in Iraq, during the Gulf War of 1991. Even more damaging are new infrasound wave transmitters, which induce hallucinations and incapacitating nausea (and possibly internal injury and death).15


Alexander had used fire—red-hot bronze statues—and, in a separate incident, noisy pigs, against elephants. Not long after Pyrrhus’s retreat from Italy in 275 BC, fire and pigs were combined in a single devilish plan to repel war elephants.

In about 270 BC, Antigonus Gonatus, the Macedonian ruler of Greece, massed his Indian war elephants to besiege the city of Megara (between Athens and Corinth). The resourceful Megarians knew the folk wisdom that elephants had a terror of squealing hogs but decided to take a further step. They smeared a bunch of pigs with flammable liquid pitch, set them on fire, and released them. These living torpedoes made a beeline for Antigonus’s lines of war-trained elephants. As the shrieking, flaming pigs rushed the elephants, the behemoths panicked. Made frantic by the sight, the noise, and the smell of the desperate burning pigs, the elephants fled trumpeting in all directions, breaking the siege. Antigonus’s confused rout at Megara must have been one of the most spectacular retreats on record. The sticky pitch-fueled flames that tortured the pigs at Megara were intended to maximize their squealing, rather than to burn the enemy forces. But one could say that the Megarian stratagem of setting pigs afire with combustible resin created the first hybrid biological-chemical weapon.

“In the future,” commented Polyaenus, “Antigonus ordered his Indian suppliers to raise the young war elephants in the company of pigs,” so the beasts would become accustomed to their appearance, smell, and shrill voices.

The last recorded use of a pig against an elephant occurred at the siege of Edessa, held by the Romans in the time of the Emperor Justinian (sixth century AD). Chosroes, king of the Persians, stormed the city, sending his biggest elephant with many soldiers on top right up to the circuit wall. Just as the Persians were about to clamber over the wall and capture the city, the quick-witted Romans grabbed a pig and suspended it directly in the face of the startled elephant. The dry-witted historian Procopius writes: “As the pig was hanging there, he very naturally gave vent to sundry squeals, and this angered the elephant so that he got out of control.” Confusion swept back in waves through the entire Persian army and, panic-stricken, they fled in great disorder.16

Fire plus animals was a combination guaranteed to wreak havoc against the enemy, as Frontinus and Appian proved in their description of a Spanish strategy against Hannibal’s father, Hamilcar Barca, in 229 BC. The Spanish front lines consisted of steer-drawn carts filled with combustibles: pitch, animal tallow, and sulphur. These carts of fuel were set afire and driven into the Carthaginian lines, causing screaming panic. Nine-year-old Hannibal went along with his father on the conquest of Spain. Perhaps he recalled the combination of steers and fire when he engineered his own rout of the Romans in 218 BC, by means of the cattle-horn torches, described earlier.

The use of animals as a delivery system to carry flammable materials occurred elsewhere in the ancient world. Chinese and Arabic military manuals, for example, suggested smearing crows and other birds with incendiary substances to set fire to enemy tents, and Kautilya’s Arthashastrarecommended attaching incendiary powders to birds, cats, mongooses, and monkeys. The flammable packages were lit and the creatures were dispatched to burn down thatched-roof structures and wooden forts. It’s not clear how these involuntary suicide bombers were persuaded to zero in on the right targets (this is precisely the problem that has now been solved with the creation of remote-controlled rats and other species that can be directed to specific targets, described above). Kautilya anticipated the problem, though: he suggested capturing only vultures, crows, and pigeons that nested in the besieged city walls. They could be trusted to fly back to their nests with the flammable powders.

Genghis Khan relied on the same “homing” principle on a large scale during his conquest of China in AD 1211. During his siege of several fortified cities, it is said that he offered to lift the siege in exchange for “1,000 cats and 10,000 swallows. “These were duly handed over,” writes the historian David Morgan, and the Mongols tied flammable materials to the tails of the birds and cats and ignited them. When the creatures were released, they fled home, setting each city on fire, and Genghis Khan easily stormed the burning cities.

In other cases, perhaps intelligent animals were trained beforehand, to offset the potential for serious backfire. In 2003, during the invasion of Iraq, it was reported that Morocco offered U.S. military two thousand monkeys from the Atlas Mountains trained to deactivate and detonate land mines. Trained primates also figure in a Chinese account from 1610 claiming that the General Tseh-ki-kwang trained several hundred monkeys from Mount Shi-Chu in Fu Tsing to shoot firearms. When the monkey militia was ordered to fire on Japanese raiders, the marauders were so terror-stricken that the general’s soldiers hiding in ambush were able to slay them all. The animal guerrillas must have been taught not to shoot at their Chinese handlers.

Friendly fire accidents caused by confused creatures carrying incendiaries would fall into the category of medieval folklore and modern urban legends collectively known as “the revenge of the exploding animal.” These tales recount the ironic consequences of tying dynamite, firecrackers, or other burning material to dogs, cats, or birds, or tossing live grenades at sharks, and so on, who inevitably circle back toward their tormentors. One Indian folktale, for example, about a flaming cat burning down a village, was collected in Kashmir. Another medieval European tale tells of a flock of birds set afire by besiegers to burn down a city. The actual use of such tactics in antiquity may be the origin of these folk motifs.

Perhaps the last instance of an animal-on-fire weapon was used by Tamerlane, the great conqueror from the East in 1398, to sack Delhi, which was protected by the Indian sultan’s 120 war elephants. Tamerlane’s warriors were usually mounted on war camels, but for this battle, Tamerlane loaded the camels with straw and ignited the bundles. As the flaming camels raced forward, the sultan’s elephants fled in panic.17

The image of terrified burning pigs or awkward flaming camels may seem amusing in a macabre way, but it only takes a slight shift of perspective to imagine the terror and pain that would be experienced by human beings set afire with unquenchable, corrosive flames. And that brings us to the final chapter, about ancient chemical incendiaries, culminating in some of the most inhumane weapons ever devised.

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