The Romans used bees and hornets by catapaulting them at their enemies - to the extent that some historians blame this use for a shortage of hives during the latter years of the Roman Empire.

Anthrax and the plague have been implicated as the fifth plague of Egypt in the fifteenth century B.C.

It is difficult to be certain about the exact identifications as these diseases affect the soft tissues that decay rapidly after death.

It may even have been lost to the Byzantines - when Constantinople fell into the hands of the Crusaders in 1204 A.D., Greek fire was nowhere to be found.

The Romans, despite the declaration of their Jurists, were not above poisoning wells when it suited them. For instance, when, after defeating Aristonicus in Asia Minor (Caria), the Romans were faced with guerrilla warfare by the remnants of Aristonicus' army, they poisoned the wells that the guerillas and their supporters used. The result was the end of the war leaving Rome in control of the region.

Poisoning of wells also occurred in the 19th Century during the American Civil War and in South Africa during the Boer War and continues to this day with the Kurdish Workers Party (PKK) of Turkey reported to have poisoned wells in Turkish Kurdistan in mid-1997.

A woman named Locusta would become particularly infamous as a poisoner in Rome; she would also be one of the first to systematically investigate the use of poisons with state (or, at least, Imperial) sponsorship. Convicted for a multiplicity of crimes under Claudius, she was sentenced to death, but the sentence had not been carried out when Claudius died (the delay in the execution of her sentence is said to have been arranged by Agippina, the wife of Claudius and mother of Nero, so that Locusta might prepare a poison for Agrippina to use on Claudius). Subsequently, the new Emperor Nero is supposed to have asked Locusta to prepare a potion for use on Nero's half-brother, Britannicus. Once Brittanicus died, Nero suspended the death penalty and made Locusta his advisor on poisons. In due course, he organized a school of poisoning where she could tutor others and conduct experiments aimed at determining how to poison and how to defend the person of the Emperor against poison. Surviving accounts indicate that many tests were performed on animals and that at least some tests were performed on convicted criminals. (Nero's preferred poison is said to have been cherry laurel water, which contains cyanide.)

• arrows dipped in blood mixed with manure (Scythian archers, ca. 400 B.C., and others)
• arrows dipped in curare (Amazonian Indians)
• arrows poisoned with batrachotoxin from frogs (Hawaiian Islanders)
• grenade shrapnel contaminated with botulinus toxin (WW II)
• ricin-filled pellets (Cold War)

In 187 B.C., the inhabitants of the town of Ambracia in Epirus dealt a setback to Roman soldiers seeking to tunnel under their walls:

Plutarch, in his Life of Sertorius, tells us of how that worthy soldier dealt with the Characitanes, who had a redoubt formed from a series of caves that seemed impregnable. Noticing that the prevailing winds blew from the North, and that the openings of most of the caves faced the North, Sertonius had his soldiers pile up a mound of earth in front of the redoubt. As the breeze began to blow, he had his soldiers turn the earth over, and his calvary ride over it, raising a cloud of somewhat caustic dust - what might be called a particulate aerosol today - that blew into the caves, blinding and choking the Characitanes. After two days of this treatment, they surrendered, "adding, by their defeat, not so much to the power of Sertorius, as to his renown, in proving that he was able to conquer places by art, which were impregnable by the force of arms".

The Romans also practiced anticrop chemical warfare, most famously after the defeat of Carthage, when the fields were sown with salt to help prevent resettlement.

The most famous incendiary mixture is certainly the Greek fire of the Byzantine Empire (Greek fire is a modern name - the Byzantines called it "sea fire"; their Moslem enemies "Roman fire"). The secret of this weapon is supposed to have been brought to the Byzantines by a refugee from Moslem-occupied Syria named Kallinikos (or Callinicus; the name is almost certainly a pseudonym - it means handsome winner, possibly a reference to the reward received for his invention). There was nothing particularly new about liquid fire - oil-based incendiaries had been used for some time. But this material had the astonishing property of burning on (or at least, when in) contact with water. Using it in combination with a spray device that allowed them to direct it against enemy ships, the Byzantines were able to utterly defeat the Arab fleet at the battle of Kyzikos in 678 A.D. - a remarkable achievemnt given that the Arabs had previously defeated the Byzantine fleet on an almost regular basis. The Byzantines had developed a decisive weapon, and they held it closely to keep their enemies from learning how to use or counter it. Their success with developing tactics to use the weapon, and in keeping others from using it, would serve them in good stead - Greek fire would be credited with many more victories - against the Moslems again in 717-718 A.D. and later against Russian attacks in 941 A.D. and 1043 A.D. The Moslems did not leave many commentaries about the use of this weapon against them, but the Rus, after their attack in 941 A.D., recorded the observation that "The Greeks possess something like the lightning in the heavens, and they released it and burned us. For this reason we did not conquer them."

Distillation of petroleum, to produce fractions ("white water naphtha") suited for incendiaries, was also known. A workshop for producing incendiary grenades, complete with a distilling furnace and a gasoline storage container, dating from the first half of the thirteenth century has been found in Hama, in Syria. The Book of Horsemanship and the Art of War, written by Najm al-Din Ahda in 1285, even tells how to build rockets with fire bomb warheads.

The Moslems seem to have avoided the intentional use of toxic additives in their flame weapons, perhaps because of injunctions in the Koran against poisoning the air and water.

Even nominally peaceful travel was a boon to the spread of disease. As Europe began to explore and colonize Africa and the New World, new diseases ravaged explorers, settlers, and natives. Venereal disease, apparently reimported from the New World and Yellow fever from Africa killed many. It was the mosquito-ridden swamps of the coastal regions of West Africa that gave rise to the term "The White Man's Grave." On the other hand, smallpox introduced by a single victim in the Cortez expedition killed 90% of the Aztecs of Mexico and in the far north the Eskimos were ravaged by epidemics of measles.

While it may be argued that the intent of casting decomposing carcasses was simply to harass (which it certainly did) or perhaps to have something to throw during a brief shortage of the more usual stones, it seems almost certain that the aims included at least a hope on the part of the attackers that the defenders would be stricken with disease. After all, one of the prevailing theories of disease transmission of the period was that disease were caused by "bad air".

Legend has it, probably not completely correctly, that the Black Death that killed a quarter of Europe's population in the 14th Century was spread by refugees from the siege of the Genoese settlement of Kaffa in the Crimea when the Tartars used the bodies of plague victims as ammunition during the siege. Whatever the truth of this allegation, there is no question that the plague had a dramatic effect on both sides. Plague was already raging through the ranks of the Tartars when they started casting the bodies over the walls. Plague then also broke out among the defenders, leaving them too weakened and demoralized to take advantage of the situation (according to one chronicle, only one in several thousand retained health enough to flee).

throw poison in the form of powder upon galleys. Chalk, fine sulfide of arsenic, and powdered verdegris may be thrown among enemy ships by means of small mangonels, and all those who, as they breathe, inhale the powder into their lungs will become asphyxiated.

Gunpowder-like mixtures - mixtures containing charcoal, sulfur, and saltpeter - were known in China by 1044 A.D., primarily as incendiaries, since the proportions were not right nor were they confined for a bang to occur. By 1232, the Chinese had developed rockets and a weapon called "Heaven-shaking Thunder", an iron bomb attached to a chain which could be lowered from the walls of a city to explode among attackers. By 1280 A.D., at least the knowledge that adding saltpeter to incendiary compositions made them work better was widespread, as a book on war engines written by a Syrian, one al-Hasan ar-Rammah, appeared which included instructions for its use and purification. At about the same time, a number of compositions which would explode, at least weakly, are described in such tomes as the Liber Ignium (Book of Fire) of Marchus Graecus. Very soon after this time the use of these materials to throw projectiles from what came to be known as guns began.

Initially, the projectiles were simply stones, but as time went by, a variety of new projectiles were developed. Explosive shells, with a powder charge ignited by a fuse lit just before firing it against the enemy appeared. And so did an incendiary shell that was called, in the proper terminolgy of artillery, the carcass, also called, by those that were not artillerymen (and some few who were), the stink pot. The carcass was a hollow metal shell with perforations for the emission of flame and flaming material, and, if one wonders why that would give rise to the sobriquot of stink pot, consider that the usual fill of a carcass included sulphur, tallow, rosin, turpentine, saltpeter, and antimony.

It was quickly observed that firing carcasses at an enemy could provide, at the least, considerable distraction as a result of the action of the fumes even when the primary goal of starting fires was not achieved. While never losing their primary function as starters of fires, a variety of fills were developed for carcasses that were intended to maximize the effects of the smoke. It is said that the gunners of the Imperial Artillery were particularly prone to the use of toxic fills during the Thirty Years War. The experience with noxious smokes would lead to speculation and some experimentation in the years to come.

The practice of variolation was introduced by Circassian traders to the Ottoman Empire, where it was practiced beginning no later than 1670.

Across the sea, in England's American colonies, the practice was accepted even earlier than in England. In 1721, the Reverend Cotton Mather had prevailed on Dr. Boyston to variolate some 244 people in an effort to halt a smallpox epidemic in Boston. When the deaths were tallied (six of the variolated against 844 of 5980 infected who had not been variolated) it was clear that variolation was the way to protect against the smallpox. By the 1750's, no less a personage than Benjamin Franklin was promoting the technique.

But the popularization of variolation was a two-edged sword. Those living in the countries where variolation was popular could be presumed to know:

• that smallpox in previously unexposed population could be devastating,
• that smallpox could reliably be produced by exposing healthy individuals to materials obtained from smallpox victims,
• that individuals seemed to become infected only once, and
• that the dangers of smallpox could be significantly reduced by the practice of variolation.

Washington had himself been a victim of smallpox, and in 1776 saw his attack on Quebec fail in large part because many soldiers were affected by an outbreak of smallpox (which many believed, albeit with small evidence, to have been the work of the British, judging by the testimony given to a Congressional hearing on the attack). He knew what the disease could do, and had come to regard it as "the greatest enemy of the Continental Army". But he also knew what to do - variolate. On January 6, 1777 he issued to Dr. William Shippen, Jr., Director General of the Hospitals and Physician in Chief to the Army, an order to inoculate all the Continental troops and the new recruits, also advising him to keep "the matter as secret as possible". danger was past.

The idea of speading smallpox to the rebels was discussed openly. Robert Donkin's 1777 book, "Military Collections and Remarks", published in New York, contains a footnote picturesquely suggesting that the rebellious Americans would disband in fear if the British should " Dip arrows in matter of smallpox and twang them at the American rebels, in order to inoculate them."

For the first time in history, measures had been taken to secure an army against, not only the very real risk of natural infection, but also against the risk of a deliberate biological attack. And they worked - after 1777 the Continental Army was never hampered by smallpox in its operations again.