Aquillius finally brought the Asiatic war
to a close by the wicked expedient of
poisoning the springs of certain cities.


SUCCUMBING TO THIRST is a terrible way to die.

The Greek historian Thucydides described the horrific outcome of the rout of the Athenians after they invaded Sicily in 413 BC, their worst defeat in the Peloponnesian War. In their failed siege of Syracuse, the Athenians had destroyed the pipes conveying drinking water to the city, a common practice in ancient warfare. But the tide shifted and the Syracusans retaliated in kind. They chased the demoralized Athenian forces overland, constantly denying them access to water. When the parched army, already sickened by swamp fevers, finally reached a river, chaos erupted as the mass of delirious soldiers trampled each other trying to reach the water. The Syracusans stood on the cliffs above and slaughtered the Athenians, who kept on drinking the muddy water, now fouled with blood and gore, until the river was dammed up with heaps of bodies.

In the next century, in India, the Greek army of Alexander the Great was so wracked by thirst that the desperate soldiers would leap into wells, armor and all. The historian Strabo wrote that the crazed men drowned trying to drink while submerged. Their bloated corpses floated to the surface, corrupting their only available source of water. In this case, the Greek army polluted their own water, but Indian strategists of that era knew many ways of poisoning water along enemy routes.

Cutting off an enemy’s water supply to force surrender was an effective—and common—method of attack, but thirst could be compounded by compelling foes to drink foul waters. Actually poisoning the water was a more subtle strategy, especially effective in siege-craft. A related large-scale biological ploy was to take advantage of unhealthy terrain. The enemy could be maneuvered into malarial marshes or other environments where bad water or air ensured that illness would take a high toll.1


The earliest historically documented case of poisoning drinking water occurred in Greece during the First Sacred War. In about 590 BC, several Greek city-states created the Amphictionic League to protect the religious sanctuary of Delphi, the site of the famous Oracle of Apollo. In the First Sacred War, the League (led by Athens and Sicyon) attacked the strongly fortified city of Kirrha, which controlled the road from the Corinthian Gulf to Delphi. Kirrha had appropriated some of Apollo’s sacred land and mistreated pilgrims to Delphi. According to the Athenian orator Aeschines (fourth century BC), the Amphictionic League consulted the Oracle of Apollo at Delphi about Kirrha’s religious crimes.

The oracle responded that total war against the city was appropriate: Kirrha was to be completely destroyed and its territory laid waste. The League added a curse of their own, in the name of Apollo: the land should not produce crops, all the children should be monstrous, the livestock should also have unnatural offspring, and the entire “race should perish utterly.” The biological disaster described in the curse evokes an eerie “nuclear winter” scene. Then, taking into their own hands Apollo’s divine powers of sending sickness, the League destroyed the city of Kirrha by means of a biological stratagem. The event received a remarkable degree of attention from ancient historians.

During the siege of Kirrha, someone “thought up a contrivance.” Depending on whose account one reads, four different historical individuals were credited with variants of the plan. According to the military strategist Frontinus (writing in the first century AD), it was Kleisthenes of Sicyon, the commander of the siege, who “cut the water-pipes leading into the town. Then, when the townspeople were suffering from thirst, he turned on the water again, now poisoned with hellebore.” The violent effects of the poison plant caused them to be “so weakened by diarrhea that Kleisthenes overcame them.”

In the account of Polyaenus (second century AD), “the besiegers found a hidden pipe carrying a great flow of spring water” into the city. Polyaenus says it was General Eurylochos who advised the allies “to collect a great quantity of hellebore from Anticyra and mix it with the water.” Anticyra was a port east of Kirrha, where hellebore grew in great profusion. The Kirrhans “became violently sick to their stomachs and all lay unable to move. The Amphictions took the city without opposition.”2

Pausanias visited the site of Kirrha in about AD 150, more than seven hundred years after its destruction. “The plains around Kirrha are completely barren, and people there will not plant trees,” he wrote, “because the land is still under a curse and trees will not grow there.” Pausanias attributed the fateful plan to Solon, the great sage of Athens. In this account, Solon diverted the channel from the River Pleistos so that it no longer ran through Kirrha. But the Kirrhans held out, drawing water from wells and collecting rainwater. Solon then threw “a great quantity of hellebore roots into the Pleistos.” When he determined that “the water was drugged enough, he sent it back through the city.” “The parched Kirrhans glutted themselves on the contaminated water, and of course became extremely ill,” wrote Pausanias. “The men defending the walls had to abandon their positions out of never-ending diarrhea.” Helpless to respond to the attack, the people of Kirrha were annihilated as the League hoplites overran the city.

The use of a treacherous ruse to breach a city’s defenses, which then resulted in further atrocities inside the city, echoes what happened in Troy, in the aftermath of the Trojan Horse trick. That subterfuge was followed by the rape of Trojan women and the massacre of children and old people by the Greek warriors. In both myth and history, there is evidence that once an army has resorted to insidious strategies outside the conventions of combat, it is not uncommon for further violations to ensue, such as the mass killing of noncombatants. Unconventional strategies often result from frustration, and when devious or unscrupulous behavior appears to be the only way to victory, the door is then opened to atrocities.

The destruction of Kirrha in 590 BC features some other striking mythological coincidences. The town happens to be located near the place where the Centaur Nessus was said to have died of the Hydra-venom arrow shot by Hercules, just west of Delphi. According to ancient legend, the Centaur’s rotting carcass poisoned the area’s water, making it unhealthy to drink. In the mid-nineteenth century, H. N. Ulrichs of the Bavarian Academy of Sciences discovered a brackish spring near Kirrha that induces violent diarrhea. Possibly, the besiegers’ knowledge of that naturally foul spring was the inspiration for their idea of poisoning the Kirrhans’ water with the violent purgative hellebore.3

The fourth man credited with the plan to poison Kirrha was a doctor named Nebros, an asclepiad, or follower of the legendary healer Asclepius, son of Apollo. According to ancient medical sources, Nebros was an ancestor of the great physician Hippocrates, author of the Hippocratic Oath in the fifth century BC. The account that implicates Nebros is the earliest known source, written only a century after Kirrha’s destruction and during Hippocrates’ lifetime. It comes from the medical writer Thessalos, reportedly a son of Hippocrates. Thessalos visited Athens in the late fifth century BC as an ambassador from Cos, the seat of Hippocratic medicine. He wrote that after a horse’s hoof had broken open the secret pipe carrying Kirrha’s water supply during the siege, Nebros helped the besiegers “by introducing into the aqueduct a drug that brought intestinal illness to the Kirrhans, allowing the allies to take the town.”

The involvement of a doctor in the destruction of the populace of Kirrha is startling. By sending sickness to Kirrha, did Nebros see himself as carrying out Apollo’s wrath on the town? That seems possible, given the sacred oracle and the curse used to justify total war. Perhaps in an attempt to rationalize Nebros’s participation in the town’s destruction, Thessalos avoided naming the drug, although it was identified by all the other sources as hellebore. And he implied that its debilitating effects were only temporary.

But the implication that the drug’s effects were only temporary was duplicitous in this case. Everyone—especially doctors—knew that hellebore was extremely dangerous and that the dosage in medical treatments was notoriously difficult to calibrate. Hellebore was known to kill large animals, and it was used as a deadly arrow poison. Doctors never prescribed hellebore for the old or weak, or for women or children. Clandestinely contaminating a city’s drinking water with “a great quantity of hellebore” would sicken not just the guards and soldiers of Kirrha, but all the people inside the city walls, young and old. Taken by surprise and already suffering from thirst, they would have had no time to try to prepare antidotes. To deliberately harm noncombatants was proscribed by the ancient Greek notions of fair war, but during sieges of cities the entire population was considered the enemy.

The ancient attempt to justify use of a “temporary” toxin to soften resistance was echoed in a modern biochemical attack on noncombatants in Iraq, in 1920. After the fall of the Ottoman Empire in 1917, the British occupation of Iraq was resisted by the Kurds. According to Geoff Simons in his 1994 book, Iraq: from Sumer to Saddam, in 1920 the colonial secretary Winston Churchill proposed a “scientific expedient” to quell the “turbulent tribes” of Kurdistan. He suggested using poison gas as a preliminary measure in bombing operations against the villages. Some British authorities protested that the villagers were defenseless and had no medical knowledge of antidotes. Discounting the protestors’ “squeamishness about the use of gas . . . against uncivilised tribes,” Churchill claimed that the chemical gas—which had only recently caused such devastation and moral revulsion in the First World War—would inflict “only discomfort or illness, but not death,” and would be a good way to demoralize the enemy.

In reality, however, the gas caused blindness, and killed children, the infirm, and the old. Like Kirrha, the Kurdish villages were easily wiped out after the poison was administered. And in keeping with the timeless tendency to further violate codes of war once a rule of fair war has been transgressed, several newly developed inhumane weapons were first tested in Kurdistan with devastating effects.4

Mirko Grmek, the Croatian historian of science who devoted his career to medical ethics, has given some thought to the story of Kirrha. He points out that it was in the interest of Thessalos, a practitioner of the healing arts and a son of Hippocrates, to try to exonerate Nebros, a fellow physician and an ancestor of Hippocrates, for devising a plan that so obviously violated the Hippocratic ideal that a doctor should do no harm. The famous Hippocratic Oath was not formally written down until the time of Thessalos in the fifth century, but earlier doctors in the tradition of Asclepius, like Nebros, were still supposed to heal, not injure. The poisoning of Kirrha is a classic example of using specialized natural knowledge to harm humanity rather than to do good. The incident makes one wonder: Was the unscrupulous role of his ancestor Nebros at Kirrha what moved Hippocrates to write the oath?

We can’t know that, of course, but it is fascinating to find a doctor implicated in the oldest version of the first recorded incident of poisoning a civilian population in war. This is the earliest report of a medical professional helping to wage biological warfare, but it is certainly not the last. Nebros’s actions have been repeated down through history, and around the globe. For example, an Italian physician was responsible for deploying contagion against French forces in 1495, and French doctors carried out similar acts during the Franco-Prussian War. An American surgeon was court-martialed for deliberately spreading yellow fever during the Civil War and medical horrors on a vast scale were perpetrated by Nazi and Japanese doctors during World War II. In South Africa, revelations during the 1999 trial of Dr. Wouter Basson, the eminent cardiologist who founded the government biochemical program in the 1980s to create an arsenal of poisons to be used against anti-apartheid activists, led to his sobriquet “Dr. Death.”5


The oracle and the curse against Kirrha were used to justify the unusual ferocity of the First Sacred War in 590 BC. A few scholars have suggested that the destruction of Kirrha may have been a legendary event, but the fact that it is mentioned in a recorded speech by the Athenian orator Isocrates and so many other credible writers has convinced most historians that it really took place. As Grmek concluded, whether the defeat of Kirrha by hellebore was legend or fact, the story of the poisoned water—and the attention it received from historians of the age —reveals the deep ambivalence over using biological measures in antiquity. Even the fact that four different men were implicated implies that people were uneasy about assigning blame or taking credit for the act.

Was there a debate outside the walls of Kirrha among the League allies about the morality of using hellebore, just as some British authorities protested Churchill’s plan to gas the Kurds in 1920? That, we’ll never know, but we do know that remorse about the method of the destruction of Kirrha was acted upon in the aftermath of the destruction. In an ancient forerunner to the 1924 Geneva Convention (in response to the bio-terror of gassing in World War I), after the battle of Kirrha the defenders of the sacred site of Delphi agreed that poisoning water was unacceptable in a religious war, or among the allies of Delphi should they ever find themselves at war with one another. According to the Amphictionic League’s new rule of war, articulated by the Athenian orator Aeschines, contaminating drinking water was to be forbidden in conflicts of a special, sacred nature.

As military historians note, rules against using biological weapons are nearly “as old as the weapons themselves,” but their effect has always been fleeting and inconsistent. For example, the Laws of Manu, the code of conduct for high-caste Hindus dating to about 500 BC, is considered the earliest attempt to prohibit biological and chemical strategies in a culture where poisons and subterfuges were pervasive and widely accepted. As described in chapter 2, however, the Harmatelians of India attacked Alexander the Great’s army with deadly snake-venom arrows, even though theLaws prohibited them. When one “fights foes in battle,” stated the Laws, “let him not strike with concealed [or treacherous] weapons, nor with weapons that are barbed or poisoned or blazing with fire.” Yet theLaws also advised “spoiling the enemy’s water,” and the military treatise of the same era, the Arthashastra, urged rulers to use a vast arsenal of biochemical weapons.6

Despite the good intention of the rule against tampering with water, drawn up after the First Sacred War, many incidents and rumors of poisoning besieged towns and enemy troops were recorded after Kirrha. Not all instances evoked criticism, however. Purelydefensive biological tactics seemed justified. For example, in 478 BC the Athenians deliberately fouled their own cisterns as they abandoned their city to the Persian invaders led by Xerxes. They were following an accepted, age-old defensive practice—known as the “scorched earth” policy—of burning one’s own crops and spoiling foodstuffs and water and other resources in order to leave nothing of use to conquering armies.

The defensive principle legitimated biological strategies against aggressors. But the idea of an aggressor surreptitiously poisoning the water supplies of unsuspecting people trapped inside a city, as happened to Kirrha, was more troubling. Evidence that such practices were suspected in antiquity appeared in The History of the Peloponnesian War, by the Athenian historian Thucydides. While the Athenians were trapped in their city by the Spartans in 430 BC, a devastating plague broke out suddenly in the harbor of Athens, and—perhaps recalling the famous story of Kirrha—the Athenians’ first reaction was to accuse the Spartans of poisoning their wells.

After the Peloponnesian War, the general known as Aeneas the Tactician drew on his own and others’ wartime experiences to write (in about 350 BC) a siege-craft manual for military commanders. Aeneas recommended several biological tactics. One was to “make water undrinkable” by polluting rivers, lakes, springs, wells, and cisterns. In 1927, the British commentators on Aeneas were shocked, and declared that “this horrible practice was against the spirit of Greek warfare.” But as the Kirrha episode showed, the expedient has appealed to ruthless war leaders from early antiquity onward. Examples can be found around the world, from ancient India and China to the New World. In North America, for example, more than one thousand French soldiers were decimated by illness after Iroquois Indians deliberately polluted their drinking water with flayed animal skins in 1710. Tossing animal carcasses into wells was a standard practice during the American Civil War, and in countless conflicts before and since.7


FIGURE 14. Women drawing water at a fountain house. During a siege, a city’s water supply could be poisoned. Hydria, 520-510 BC.

(Toledo Museum of Art, Libbey Endowment, Gift of Edward Drummond Libbey)


Interfering with water by diverting rivers was another age-old environmental ploy in war. Frontinus, the Roman commander and author of Stratagems, had campaigned against the savage Silures of Wales, the Chatti of Germany, and “other troublesome people” at the fringes of the Roman Empire. His book, written in a popular style accessible to military leaders, presents numerous examples of clever and successful war strategies from Greek and Roman history, including the poisoning incident at Kirrha. Frontinus’s interests in quelling bellicose tribes, and later his office as Manager of Aqueducts at Rome, were combined in a section of his book titled “On Diverting Streams and Contaminating Waters.”

On diverting rivers, he wrote of Semiramis, the legendary queen of Assyria (seventh century BC), who boasted in an inscription that she had extended her borders with courageous and cunning conquests: “I compelled rivers to run where I wanted, and I wanted them to run where it was advantageous.” According to Frontinus, Semiramis conquered Babylon with a brilliant water trick. The Euphrates River flowed through the city, dividing it in two. Semiramis, who undertook many waterworks projects in her reign, had her engineers divert the river, so that her army could march right into the city in the dry riverbed. The very same feat was attributed by other authors to the mythical witch Medea and to two historical conquerors of Babylon, the Persian king Cyrus and Alexander the Great.

A stream was diverted to literally flush out an enemy by the Roman commander Lucius Metellus, fighting in Spain in 143 BC. The Spaniards had foolishly camped in an easily flooded plain alongside a stream. The Roman legionaries damned the stream and waited in ambush to slaughter the panicked men as they ran for high ground. Some years later, in 78-74 BC, Rome began a difficult campaign in a rugged region of Asia Minor called Isaura (in eastern Turkey). The Isaurians were fiercely independent mountaineers, labeled as “brigands and bandits” by the Romans. Publius Servilius, leader of the campaign, finally reduced the fortified towns of Isauria by diverting the mountain streams where the Isaurians drew their water, “and he thus forced them to surrender in consequence of thirst.” A couple of decades later, Julius Caesar, on his campaign in Gaul (now France), diverted the water of the city of Cadurci. Because the town was surrounded by a river and many springs, this took a lot of labor, digging extensive networks of underground channels. Then Caesar stationed his archers to cut down any Gauls who attempted to reach the river. The stratagem was successful: Cadurci surrendered in 51 BC.

Polyaenus, a Macedonian lawyer from Bithynia, wrote a military treatise for the Roman emperors Lucius Verus and Marcus Aurelius in AD 161. In it he claimed that the mythic hero Hercules had changed the course of a river in Greece to destroy the Minyans because he was afraid to face such skilled cavalrymen in open battle. The story was intended to justify reliance on devious tricks, instead of risky face-to-face battles, for the co-emperors who were facing a daunting war against the invincible Parthians of Central Asia. The Parthians, renowned for their armored cavalry and formidable horse archers, had just invaded the eastern empire and, in fact, were never defeated by the Romans.

Cunning tricks like diverting rivers to gain access to a city or to cause floods are examples of creative unconventional warfare, not true biological strategies based on special natural knowledge. Unless such ploys killed entire populations by drowning (as occurred in some Islamic attacks by flooding in the early Middle Ages) diverting rivers aroused little moral tension, because a well-prepared city or army should be able to anticipate or counter such tactics. But secretly poisoning the water or food supplies that the enemy must depend on was another matter—and such insidious practices often raised ethical questions in ancient societies. In the Punic Wars against Carthage in North Africa (264-146 BC), for example, the Romans were accused of polluting wells with carcasses of animals. But many Romans bristled at the idea of resorting to poisons of any sort in warfare, as not in keeping with traditional ideals of Roman courage and battle skills.8

After a revolt was quelled in Asia in 129 BC, for example, disturbing reports circulated in Rome claiming that the consul Manius Aquillius had defeated the rebelling cities by pouring poison in their cisterns. Aquillius was a cold-blooded general notorious for his harsh military discipline—whenever his lines were broken by the enemy, it was his habit to behead three men from each century (a unit of one hundred) whose position was breached. The historian Florus, who compiled his grandiose History of All the Wars over 1,200 Years in about AD 140, described what happened in Asia.

The insurrection, led by Aristonicus of Pergamum, challenged Roman rule in the newly declared Province of Asia Minor. The rebellion was especially threatening to the Romans because Aristonicus was mobilizing slaves and lower classes, and he was succeeding: Several important cities in Asia Minor had joined the revolt before the Romans arrived in 131 BC. Aristonicus was captured at last and executed in Rome, and Aquillius, wrote Florus, “finally brought the Asian war to a close.” But his victory was a clouded one, because Aquillius had used “the wicked expedient of poisoning the springs to procure the surrender” of the rebel cities. Florus was clear about the immorality of such measures. “This, though it hastened his victory, brought shame upon it, for he had disgraced the Roman arms, which had hitherto been unsullied by the use of foul drugs.” Aquillius’s measures, thundered Florus, “violated the laws of heaven and the practice of our forefathers.”

Florus’s ringing condemnation of “un-Roman warfare” would have appealed to many Romans. His patriotic nostalgia obscured earlier incidents of well- and crop-poisonings in the Romans’ ruthless wars against Carthage, however, not to mention countless political assassinations by poison during the republic and empire. Tacitus, the moralistic historian of the reigns of Rome’s first two emperors, Augustus and Tiberius, referred to similar nostalgic ideals of honor in his Annals of Imperial Rome. In AD 9, a rebellion in Germany led by the brilliant chieftain Arminius had resulted in the treacherous destruction of three Roman legions. The Germans had cleverly lured the legionaries into the marshy Teutoburg Forest (near Osnabruck) and slaughtered them as the men and horses foundered in the difficult terrain. A war-chief of the neighboring Chatti tribe wrote to the emperor Tiberius offering to poison Arminius.

Professing to be deeply offended by the offer, the emperor replied to the Chatti chief: “Romans take vengeance on their enemies, not by underhanded tricks, but by open force of arms.” By this “elevated sentiment,” commented Tacitus, Tiberius compared himself to noble “generals of old” who had rejected plans to poison the invader Pyrrhus when he was ravaging Italy in the third century BC. “We Romans have no desire to make war by trickery,” had been their reply to the would-be assassins.

Historians like Tacitus and Florus and their audiences greatly admired Virgil, the poet-propagandist commissioned by the emperor Augustus to write the epic saga of the glorious origins of Rome and the story of how the legendary forefathers of Rome, the Trojans, had colonized Italy after the Trojan War. The imperial historians chose to overlook a salient passage in Virgil’s Aeneid, in which stated that among Rome’s founders there was an expert at poisoning arrows and spears.9


Besides poisoning a city’s wells, one could take advantage of naturally unhealthy environments—or even create a contaminated environment to sicken and disable foes. Contaminating water and vegetation along the route of an enemy’s march was a well-known stratagem in ancient India and Kautilya’s Arthashastra suggested several poison mixtures for polluting the foodstuffs and drink of the enemy. In Book 14, chapter 1, “Ways to Injure an Enemy,” he described powders and ointments made from various plants, animals, insects, and minerals that caused blindness, disease, insanity, lingering death, or instantaneous death. Some of the ingredients were thought to have magical properties (crabs, goat hoof, snake skin, cow urine, ivory, peacock feathers), but many others were truly poisonous. There was special smoke to destroy “all animal life as far as it is carried off by the wind,” and certain compounds that would poison grass and water to kill livestock. One powerful mixture of toxic plants and minerals could contaminate a large reservoir “one hundred bows long”: it killed all the fish and any creature who drank or even touched the water. One could even poison “merchandise,” such as spices or cloth, and send it to the foe.

Notably, Kautilya also provided remedies for these biological weapons, in case of backfire that threatened one’s own troops, or retaliation in kind by enemies. Other Indian writers explained how to counter military poisons, too. According to an ancient medical treatise by Susruta, the Susruta Samhita, composed between the sixth century and first century BC, deliberately polluted water could be detected and purified with mineral and plant antidotes, and special rituals. Water that has been poisoned, wrote Sushruta, “becomes slimy, strong-smelling, frothy, and marked with dark lines on the surface. Frogs and fish die without apparent cause [and] birds and beasts on its shores roam about wildly in confusion from the effects of the poison.” Countermeasures against biological contaminants combined practical agents such as charcoal or clay and alcohol, each of which have natural filtering and purifying capabilities against toxins and bacteria, along with magical incantations. For example, Sushruta recommended purification of contaminated water with ashes, an effective form of charcoal filtering. For earth, stone slabs, and animal fodders that had been poisoned, Sushruta listed antidotes such as sprinkling with perfumes, wine, black clay, and the bile of brown cows, and beating drums smeared with “anti-poisonous compounds.” Again, alcohol in wine and the absorptive clay would have had disinfectant and filtering effects.10


Avoidance of diseases and unwholesome environments that endangered their men was a key concern for military leaders. Xenophon, the Greek mercenary commander who recorded his memoirs in the fourth century BC, advised leaders to vigilantly guard the health of their soldiers. “First of all, always camp in a healthy place.” By this he meant camping where the air and waters were pure, avoiding swamps and other places where the water and atmosphere were insalubrious and caused illness.

Some lakes, streams, and valleys were infected by “miasma,” an exhalation or atmosphere known to be harmful to living things (miasma is the ancient Greek word for “pollution”). These vapors and waters were said to be so deadly that animals died on the spot and birds flying overhead dropped out of the sky. A number of these locales were places like Ephyra in western Greece, identified as entrances to the Underworld, where noxious plants thrived. Modern sciences shows that some of these locales were in fact geologically active thermal sites, where fumeroles and hot springs emitted bad-smelling sulphurous and other poisonous gases from the earth. In antiquity there was a strong association between foul odors and disease, based on experience and observation, and geologists have shown that methane and other fumes released from the earth can adversely affect humans and wildlife.11

A mythic explanation was also offered to explain the origin of a stinking marsh in the Peloponnese so baneful that the fish in it were toxic. It was rumored to be the place where a group of Centaurs, wounded by Hercules’ poison arrows, had attempted to wash away the Hydra venom. A similar place of toxic exhalations, caused by the poison arrows that killed the Centaur Nessus, was known to exist near Kirrha, the town destroyed by poison. The ancient idea that the water, land, and atmosphere had been contaminated by poison weapons from the past finds a modern counterpart in the deadly environmental pollution caused by testing or dumping biochemical and nuclear weapons.

Swamps and marshes in general were considered dangerous to the health, and with good reason: wetlands with stagnant water were breeding places of mosquitoes carrying malaria, which was endemic in certain areas in antiquity. The exact causes of fevers that emanated from swamps were not understood, but the health benefits of draining marshes was already recognized as early as the fifth century BC, when the natural philosopher-doctor Empedocles alleviated the raging fevers (now known to be malaria) that beset the Sicilian town of Selinus, by devising a sophisticated hydraulic engineering plan to drain the swamps there. (Malaria was not fully eradicated from Italian marshlands until the 1950s.)

Varro (116-27 BC), Rome’s most erudite scholar, anticipated modern epidemiology when he stated, “Precautions must be taken in the neighborhood of swamps,” because they “breed certain minute creatures which cannot be seen by the eyes, but which float in the air and enter the body through the mouth and nose and cause serious diseases.” Lucretius, a natural philosopher writing in about 50 BC, also offered a perceptive theory of invisible microbes. “In the earth there are atoms of every kind,” and although “certain atoms are vital to us, there are countless others flying about that are capable of instilling disease and hasten death.” When these harmful atoms accumulate in mists or in earth rotted by too much water, the “air grows pestiferous.” These “hurtful particles enter the body [and] many noxious ones slip in through the nostrils” when we breathe; some enter through the skin; and many are ingested through the mouth. By inhaling polluted atmospheric particles from places like swamps, wrote Lucretius, “we can’t help absorbing these foreign elements into our system.”

According to the historian Livy (first century BC) the pernicious effects of making camp in stagnant swamps brought disease to the Gauls who had sacked Rome in about 390 BC. Livy and the historian Diodorus of Sicily both described the contagion that assailed the Greeks and the Carthaginians fighting around Syracuse (Sicily) in 397 BC. The Carthaginians were harder hit, being unused to the unhealthy climate and water. “They perished to a man, together with their generals.”

Looking back to the Plague of Athens during the Peloponnesian War, Diodorus of Sicily surmised that the disease had been a result of floods the previous wet winter, which created marshes filled with “putrid, foul vapors which corrupted the air” and spoiled the crops. The Athenians, trapped in their crowded city by the Spartans that hot summer, he noted, were especially susceptible to disease. By the fourth century AD, it was a commonplace among generals that “an army must not use bad or marshy water.” “Foul water is like poison and causes plagues,” cautioned the Roman military strategist Vegetius. Moreover, if an army camps too long in one place, the air and water “become corrupt [and] unhealthy.” Without frequent changes of camp, he wrote, “malignant disease arises.”12

Xenophon’s advice to always camp in a healthy place was based in part on his knowledge of what befell the Athenians on their ill-fated expedition against Sicily in 415-413 BC. The swamp fevers that decimated the Greeks during the Sicilian disaster were described by Thucydides, Diodorus of Sicily, and Plutarch (first century AD). These historians all agreed that the Athenians’ crushing defeat in Sicily was attributable in part to fevers (probably malaria) contracted in the marshes where they made their summer bivouacs. Diodorus of Sicily pointed out that the Carthaginians who were annihilated by pestilence in 397 BC camped in the same place where the Athenians had camped.

It is not clear whether the Athenians made the fatal mistake of camping in malarial swamps on their own, or whether the Sicilians “took particular measures to lead the Athenians into such noxious conditions.” But, as Thucydides repeatedly demonstrated, the Sicilians were hyperaware of denying advantageous terrain to the Greeks, constantly depriving them of water and opportunities for foraging. It’s very likely that the Athenian invaders succumbed to a biological subterfuge by the Sicilians.

Some modern military writers exclude “maneuvering of armies into ‘unsanitary’ areas” from their discussions of biological warfare, but as Grmek notes, in antiquity this was an effective strategy based on sound biological knowledge. Knowing the ill effects of local marshes and rank water, an astute commander would ask, “How can I manipulate these naturally malignant miasmas against my enemies?” Luring or driving an enemy into these virtual minefields of microbes could be decisive.13

The German tribes were masterful at maneuvering enemies into lethal landscapes. When the Romans were fighting the Teutons in 106 BC, the military writer Frontinus assumed that the Roman engineers “had heedlessly chosen a campsite” near the Germans’ stronghold without realizing that the only water supply was the river flowing along the enemy palisades. Teuton archers would pick off anyone who attempted to drink. In this case, though, the site may have been selected by the commander, Marius, on purpose. The historian Plutarch says that Marius intended to goad his men into attacking fiercely by the biological expedient of thirst. When his desperate soldiers complained, he pointed to the river between the camp and the Teuton fort. “There is your water,” replied Marius, “but it must be bought with blood.” The Romans begged to be given the order to storm the fort “before our blood dries up!”

Recalling Germanicus Caesar’s arduous campaigns in Germany in the first century AD, Pliny the Elder noted that noxious plants and beasts were not the only treacherous things in the countryside. Certain geographical areas and their waters were also “guilty of harm.” The Germans consistently forced the Romans to fight and camp in unhealthy marshes and boggy woods (especially around modern Osnabruck), where the legionaries were easily ambushed and suffered extremely heavy losses. Tacitus described the emotions of Germanicus and his men when they came upon the jumbled masses of skeletons of horses and mutilated men, all that remained of the three Roman divisions that had been massacred six years earlier in the “sodden marsh-land and ditches” of the Teutoburg Forest by Arminius and his men. When the Romans finally managed to maneuver the Germans into fighting on level, dry ground, reported Tacitus, a spontaneous war cry rang out: “It’s a fair fight! On fair ground!”

Pliny was intrigued by the experience of the veterans of Germanicus’s campaign who had been forced to camp in the coastal wetlands of northern Germany, where there was only one place to draw drinking water. Drinking it caused disease, and even the survivors lost all their teeth and suffered severe degeneration of the joints. Ever optimistic about nature’s balance, Pliny pointed out that a remedy for these maladies grew in the swampy area, a kind of aquatic weed called britannica, known to the locals. The German manipulation of the Roman legions into a place where they would be forced to drink the infected water without knowledge of the antidote was most likely a biological stratagem.14

A particularly villainous strategic use of insalubrious terrain occurred a century or so after the Greek defeat in Sicily. What makes this event especially reprehensible is that it was the commander himself who plotted the destruction of his own men. The story comes from Polyaenus, the strategist who compiled a history of how to protect armies and overcome barbarians for the emperors at the beginning of the Parthian War.

Drawing on several historical accounts, Polyaenus told how Clearchus, a cruel tyrant (one of several evil tyrants who had studied with the philosopher Plato), took power in Heraclea, on the Black Sea, in 363 BC. He surrounded himself with mercenaries, and ordered them to sneak out at night and rob, rape, and assault the citizens of Heraclea. When the citizens complained, the tyrant shrugged: the only way to restrain the bodyguards was for the citizens to build him a walled acropolis. After ensconcing himself in his new citadel, however, Clearchus “did not check the mercenaries, but granted himself the power to wrong everyone.” Using trickery, the tyrant arrested Heraclea’s democratic Council of 300, and then he devised a vicious scheme to get rid of the rest of the dissident citizens.

All local men between the ages sixteen and sixty-five were drafted for a bogus campaign against the Thracian city of Astachus. It was the hottest part of the summer of 360 BC, and Astachus, in western Turkey, lies in an area surrounded by marshes. Pretending that he and his mercenaries “were going to bear the brunt of the siege,” Clearchus occupied the high ground with shade trees, running water, and refreshing breezes. He commanded all the citizens to camp below in a hot, breathless swamp filled with stagnant water. To exhaust them, he ordered continual guard duty. Then he “stretched out the ‘siege’ all summer until the unhealthy marshiness of the camp killed his citizen troops.” When all of the men had died, Clearchus returned to Heraclea with his mercenaries, claiming that a plague had wiped out the citizens.15

This story is shocking but certainly plausible. Any general of Clearchus’s day knew that troops forced to endure such conditions would succumb to the diseases we now know to be malaria and dysentery. (Perhaps there is grim satisfaction in knowing that a few years later, Clearchus himself was murdered.) The story of a tyrant who turned biological agents against his own people almost sounds too evil to be true, but there are too many modern examples to dismiss the tale as pure invention.

In a widely publicized attack in March 1988, for instance, Saddam Hussein responded to Iraqi Kurds’ resistance by bombing villagers with poison gas. An estimated five thousand men, women, and children were killed. After the fall of apartheid in South Africa, trial testimonies before the Truth and Reconciliation Commission in the late 1990s revealed that the South African government planned to systematically poison citizens who protested apartheid in the 1980s and early ’90s. The tale of Clearchus’s premeditated elimination of his own citizens and soldiers by forcing them to endure a deadly environment also stirs disquieting memories of well-documented, clandestine U.S. government experiments with nuclear, bacterial, and chemical agents on its own citizens and soldiers during the Cold War of the twentieth century.

As Grmek has pointed out—and as demonstrated by the numerous ancient examples of manipulating poisons and disease-ridden atmospheres to sicken foes on a large scale—it would be a mistake to assume that the ancient preoccupation with “miasmas” or “vapors” as the source of illness presented any conceptual “obstacle to utilizing contagion for military ends.” In antiquity, long before the modern terminology of epidemiology was developed, experience and observation led to insights into how disease could be used as a blunt instrument of war. Could that instrument somehow be refined into a capacity to spread epidemics among entire populations?16

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