Biological warfare (BW) has been practiced repeatedly throughout history. Before the 20th century, the use of biological agents took three major forms:
* Deliberate poisoning of food and water with infectious material
* Use of microorganisms, toxins or animals, living or dead, in a weapon system
* Use of biologically inoculated fabrics
In the 20th century, sophisticated bacteriological and virological techniques allowed the production of significant stockpiles of weaponized bio-agents:
* Bacterial agents: Anthrax, Brucella, Tularemia, etc
* Viral agents: Smallpox, Viral hemorrhagic fevers, etc
* Toxins: Botulinum, Ricin, etc
* 1 Antiquity
* 2 Middle Ages
* 3 18th century
o 3.1 North America
o 3.2 New South Wales
* 4 19th century
* 5 20th century
o 5.1 1937–1945
o 5.2 1946 to 1972
o 5.3 The BWC (1972) and after
* 6 21st century
* 7 List of historical BW programs by country
* 8 References
* 9 Other sources
The earliest documented incident of the intention to use biological weapons is recorded in Hittite texts of 1500–1200 B.C, in which victims of plague were driven into enemy lands. Although the Assyrians knew of ergot, a parasitic fungus of rye which produces ergotism when ingested, there is no evidence that they poisoned enemy wells with the fungus, as has been claimed.
According to Homer's epic poems about the legendary Trojan War, the Iliad and the Odyssey, spears and arrows were tipped with poison. During the First Sacred War in Greece, in about 590 BC, Athens and the Amphictionic League poisoned the water supply of the besieged town of Kirrha (near Delphi) with the toxic plant hellebore. The Roman commander Manius Aquillus poisoned the wells of besieged enemy cities in about 130 BC.
During the 4th century BC Scythian archers tipped their arrow tips with snake venom, human blood, and animal feces to cause wounds to become infected. There are numerous other instances of the use of plant toxins, venoms, and other poisonous substances to create biological weapons in antiquity.
In 184 B.C, Hannibal of Carthage had clay pots filled with venomous snakes and instructed his soldiers to throw the pots onto the decks of Pergamene ships. In about AD 198, the Parthian city of Hatra (near Mosul, Iraq) repulsed the Roman army led by Septimius Severus by hurling clay pots filled with live scorpions at them.
 Middle Ages
The Mongol Empire established commercial and political connections between the Eastern and Western areas of the world, but it did so through the most mobile army ever seen. The armies, being the most rapidly moving travelers who had ever moved between the steppes of East Asia (where bubonic plague was and remains endemic among small rodents), managed to keep the chain of infection without a break until they reached, and infected, peoples and rodents who had never encountered it. The ensuing Black Death may have killed almost half of the population of Europe in the next decades, changing the course of Asian and European history.
During the Middle Ages, victims of the bubonic plague were used for biological attacks, often by flinging fomites such as infected corpses and excrement over castle walls using catapults. In 1346, during the siege of Kafa (now Feodossia Ukraine) the attacking Tartar Forces which were subjugated by the Mongol empire under Genghis Khan, used the bodies of Mongol warriors of the Golden Horde who had died of plague, as weapons. An outbreak of plague followed and the defending forces retreated, followed by the conquest of the city by the Mongol army. It has been speculated that this operation may have been responsible for the advent of the Black Death in Europe. At the time, the attackers thought that the stench was enough to kill them, though it was the disease that was deadly.
At the siege of Thun-l'Évêque in 1340, during the Hundred Years' War, the attackers catapulted decomposing animals into the besieged area.
In 1422, during the siege of Karlstein Castle in Bohemia, Hussite attackers used catapults to throw dead (but not plague-infected) bodies and 2000 carriage-loads of dung over the walls.
The last known incident of using plague corpses for biological warfare occurred in 1710, when Russian forces attacked the Swedes by flinging plague-infected corpses over the city walls of Reval (Tallinn). However, during the 1785 siege of La Calle, Tunisian forces flung diseased clothing into the city.
English Longbowmen usually did not draw their arrows from a quiver, rather, they stuck their arrows into the ground in front of them. This made nocking the arrows to the bow faster and the dirt and soil was likely to stick the arrowheads. Thus making the wounds that it made much more likely to infect.
 18th century
 North America
The Native American population was devastated after contact with the Old World due to the introduction of many different fatal diseases. There are two documented cases of alleged and attempted germ warfare. The first, during a parley at Fort Pitt on June 24, 1763, Ecuyer gave representatives of the besieging Delawares two blankets and a handkerchief that had been exposed to smallpox, hoping to spread the disease to the Natives in order to end the siege. William Trent, the militia commander, left records that clearly indicated that the purpose of giving the blankets was "to Convey the Smallpox to the Indians."
British commander Lord Jeffrey Amherst and Swiss-British officer Colonel Henry Bouquet certainly discussed this, in the course of Pontiac's Rebellion; there still exists correspondence referencing the idea of giving smallpox-infected blankets to enemy Indians. Historian Francis Parkman verifies four letters from June 29, July 13, 16 and 26th, 1763. Excerpts: Commander Lord Jeffrey Amherst writes July 16, 1763, "P.S. You will Do well to try to Inocculate the Indians by means of Blankets, as well as to try Every other method that can serve to Extirpate this Execrable Race. I should be very glad your Scheme for Hunting them Down by Dogs could take Effect,..." Colonel Henry Bouquet replies July 26, 1763, "I received yesterday your Excellency's letters of 16th with their Inclosures. The signal for Indian Messengers, and all your directions will be observed."
While the intent of carrying out biological warfare is clear, there is debate among historians as to whether this actually took place despite Bouquet's affirmative reply to Amherst, and the continuing correspondence on the point. Smallpox is highly infectious and does not require contaminated blankets to spread uncontrollably, and together with measles, influenza, chicken pox, and so on had been doing so since the arrival of Europeans and their animals. Historians have been unable to establish whether or not the Amherst plan was implemented, particularly in light of the fact that smallpox was already present in the region, and that scientific knowledge of disease at that time had yet to develop an understanding of infection vectors, nor in the case of smallpox a full acknowledgment of the protective effect of a cowpox infection.
Regardless of whether the plan was carried out, trade and combat provided ample opportunity for transmission of the disease. See also: Small pox during Pontiac's Rebellion.
The diseases that struck indigenous Americans can be traced to Eurasia where people had long lived with them and developed some immunological ability to survive their presence. Without similarly long ancestral exposure, indigenous Americans were immunologically naive and extremely vulnerable.
 New South Wales
Australian aborigines (Kooris) have always maintained that the British deliberately spread smallpox in 1789, but this fact has only been apparent to historians from the 1980s when Dr Noel Butlin suggested; “there are some possibilities that ... disease could have been used deliberately as an exterminating agent”.
In 1997, David Day claimed there “remains considerable circumstantial evidence to suggest that officers other than Phillip, or perhaps convicts or soldiers … deliberately spread smallpox among aborigines” and in 2000 Dr John Lambert argued that “strong circumstantial evidence suggests the smallpox epidemic which ravaged Aborigines in 1789, may have resulted from deliberate infection”.
These claims were controversial as it was argued that any smallpox virus brought to New South Wales would have been sterilised during the voyage of the First Fleet from England and incapable of biological warfare. However, in 2007, Christopher Warren demonstrated conclusively that the British smallpox was still viable. Since then most scholars have recognized that the British committed biological warfare in 1789 near their new convict settlement at Port Jackson.
Some earlier writers, misunderstanding that British stocks of virus had been sterilised, proposed that the 1789 outbreak was caused by a hypothetical transmission from Macassar in Sulawesi. However the available records for smallpox in Macassar only show an outbreak in 1789, too late and inconvenient to be associated with the First Fleet outbreak.
 19th century
In 1834, Massachusetts diarist Richard Henry Dana visited San Francisco on a merchant ship. His ship traded many items including blankets with Mexicans and Russians who had established outposts on the northern side of the San Francisco Bay. Local histories document that the California plague epidemic began at the Russian fort soon after they left. It is possible that the blankets were the source of the contamination (hidden fleas, or rats, perhaps), but another possible source was a Chinese ship making port in San Francisco at the same time. Plague became established in California and has since become endemic throughout much of the North American West. Native rodents have suffered a severe population decline, only partly due to human eradication action.
During the American Civil War, General Sherman reported that Confederate forces shot farm animals in ponds upon which the Union troops depended for drinking water. This would have made the water unpleasant to drink, though perhaps the death caused might not have been that desired. A Confederate doctor planned and may have carried out a bacteriological attack on Northern populations across the Canadian border.
 20th century
Jack London, in his story '"Yah! Yah! Yah!"' (1909), described a punitive European expedition to a South Pacific island deliberately exposing the Polynesian population to measles, of which many of them died. While much of the material for London's South Sea Tales is derived from his personal experience in the region, it is not known whether this particular incident is historical.
During the First World War (1914-1918), the Empire of Germany pursued an ambitious biological warfare program. Using diplomatic pouches and couriers, the German General Staff supplied small teams of saboteurs in the Russian Duchy of Finland, and in the then-neutral countries of Romania, the United States, and Argentina. In Finland, saboteurs mounted on reindeer placed ampoules of anthrax in stables of Russian horses in 1916.  Anthrax was also supplied to the German military attaché in Bucharest, as was glanders, which was employed against livestock destined for Allied service. German intelligence officer and US citizen Dr. Anton Casimir Dilger established a secret lab in the basement of his sister's home in Chevy Chase, Maryland, that produced glanders which was used to infect livestock in ports and inland collection points including, at least, Newport News, Norfolk, Baltimore, and New York, and probably St. Louis and Covington, Kentucky. In Argentina, German agents also employed glanders in the port of Buenos Aires and also tried to ruin wheat harvests with a destructive fungus.
The Geneva Protocol of 1925 prohibited the use of chemical weapons and biological weapons, but said nothing about experimentation, production, storage, or transfer; later treaties did cover these aspects. Twentieth-century advances in microbiology enabled the first pure-culture biological agents to be developed by World War II.
The interwar period was a period of development by many nations, most notably the Empire of Japan. Secret Imperial Japanese Army Unit 731, based primarily at Pingfan in Manchuria commanded by Lieutenant General Shirō Ishii, did research on BW, conducted often fatal human experiments on prisoners, and produced biological weapons for combat use during the Second Sino-Japanese War.
Biological experiments, often using twins with one subject to the procedure and the other as a control, were carried out by Nazi Germany on concentration camp inmates, particularly by Joseph Mengele.
During the Sino-Japanese War (1937–1945) and World War II, the Imperial Japanese Army made use of biological weapons against both Chinese soldiers and civilians in several military campaigns. Three veterans of Unit 731 testified, in a 1989 interview to the Asahi Shimbun, that they were part of a mission to contaminate the Horustein river with typhoid near the Soviet troops during the Battle of Khalkhin Gol. In 1940, the Imperial Japanese Army Air Force bombed Ningbo with ceramic bombs full of fleas carrying the bubonic plague. A film showing this operation was seen by the imperial princes Tsuneyoshi Takeda and Takahito Mikasa during a screening made by mastermind Shiro Ishii. During the Khabarovsk War Crime Trials the accused, such as Major General Kiyashi Kawashima, testified that as early as 1941 some 40 members of Unit 731 air-dropped plague-contaminated fleas on Changde. These operations caused epidemic plague outbreaks.
Many operations were ineffective due to inefficient delivery systems, using disease-bearing insects rather than dispersing the agent as an bioaerosol cloud. Nevertheless, some modern Chinese historians estimate that 400,000 Chinese died as a direct result of Japanese field testing and operational use of biological weapons.
In 1943, following the Allied invasion at Anzio, German forces flooded The Pontine Marshes to reintroduce Malaria to the area. Perhaps 100,000 cases of the disease were noted in the region in 1944 and 43,000 in 1945. German forces withheld medical care to the civilian population.
In response to biological weapons development in Japan, and at the time suspected in Nazi Germany, the United States, United Kingdom, and Canada initiated a BW development programs in 1941 that resulted in the weaponization of tularemia, anthrax, brucellosis, and botulism toxin.
The center for United States military BW research was Fort Detrick, Maryland, where USAMRIID is currently based; the first director was pharmaceutical executive George W. Merck. Some biological and chemical weapons research and testing was also conducted at Dugway Proving Grounds in Utah, at a munition manufacturing complex in Terre Haute, Indiana, and at a tract on Horn Island, Mississippi.
Much of the British work was carried out at Porton Down. Field testing carried out in the United Kingdom during World War II left Gruinard island in Scotland contaminated with anthrax for the next 48 years.
 1946 to 1972
During the 1948 Israel War of Independence, International Red Cross reports raised suspicion that the Jewish Haganah militia had released Salmonella typhi bacteria into the water supply for the city of Acre, causing an outbreak of typhoid among the inhabitants. Egyptian troops later claimed to have captured disguised Haganah soldiers near wells in Gaza, whom they executed for allegedly attempting another attack. Israel denies these allegations.
During the Cold War, US conscientious objectors were used as consenting test subjects for biological agents in a program known as Operation Whitecoat. There were also many unpublicized tests carried out on the public during the Cold War.
E120 biological bomblet, developed before the U.S. signed the Biological and Toxic Weapons Convention.
Considerable research on the topic was performed by the United States (see US Biological Weapon Testing), the Soviet Union, and probably other major nations throughout the Cold War era, though it is generally believed that biological weapons were never used after World War II. This view was challenged by China and North Korea, who accused the United States of germ warfare in the Korean War (1950–1953).
Cuba has also accused the United States of spreading human and animal disease on their island nation.
At the time of the Korean War the United States had only weaponized one agent, brucellosis ("Agent US"), which is caused by Brucella suis. The original weaponized form used the M114 bursting bomblet in M33 cluster bombs.
While the specific form of the biological bomb was classified until some years after the Korean War, in the various exhibits of biological weapons that Korea alleged were dropped on their country nothing resembled an M114 bomblet. There were ceramic containers that had some similarity to Japanese weapons used against the Chinese in World War II, developed by Unit 731.
Some of the Unit 731 personnel were imprisoned by the Soviets, and would have been a potential source of information on Japanese weaponization. The head of Unit 731, Lieutenant General Shiro Ishii, was granted immunity from war crimes prosecution in exchange for providing information to the United States on the Unit's activities.
The Korean War allegations also stressed the use of disease vectors, such as fleas, which, again, were probably a legacy of Japanese biological warfare efforts. The United States initiated its weaponization efforts with disease vectors in 1953, focused on Plague-fleas, EEE-mosquitoes, and yellow fever - mosquitoes (OJ-AP). However, US medical scientists in occupied Japan undertook extensive research on insect vectors, with the assistance of former Unit 731 staff, as early as 1946.
The United States Air Force was not satisfied with the operational qualities of the M114/US and labeled it an interim item until the United States Army Chemical Corps could deliver a superior weapon. The Air Force also changed its plans and wanted lethal biologicals.
The Chemical Corps then initiated a crash program to weaponize anthrax (N) in the E61 1/2-lb hour-glass bomblet. Though the program was successful in meeting its development goals, the lack of validation on the infectivity of anthrax stalled standardization.
Around 1950 the Chemical Corps also initiated a program to weaponize tularemia (UL). Shortly after the E61/N failed to make standardization, tularemia was standardized in the 3.4" M143 bursting spherical bomblet. This was intended for delivery by the MGM-29 Sergeant missile warhead and could produce 50% infection over a 7-square-mile (18 km2) area.
Unlike anthrax, tularemia had a demonstrated infectivity with human volunteers (Operation Whitecoat). Furthermore, although tularemia is treatable by antibiotics, treatment does not shorten the course of the disease.
In addition to the use of bursting bomblets for creating biological aerosols, the Chemical Corps started investigating aerosol-generating bomblets in the 1950s. The E99 was the first workable design, but was too complex to be manufactured. By the late 1950s the 4.5" E120 spraying spherical bomblet was developed; a B-47 bomber with a SUU-24/A dispenser could infect 50% or more of the population of a 16-square-mile (41 km2) area with tularemia with the E120. The E120 was later superseded by dry-type agents.
Dry-type biologicals resemble talcum powder, and can be disseminated as aerosols using gas expulsion devices instead of a burster or complex sprayer. The Chemical Corps developed Flettner rotor bomblets and later triangular bomblets for wider coverage due to improved glide angles over Magnus-lift spherical bomblets. Weapons of this type were in advanced development by the time the program ended.
United States President Richard Nixon signed an executive order on November 1969, which stopped production of biological weapons in the United States and allowed only scientific research of lethal biological agents and defensive measures such as immunization and biosafety. The biological munition stockpiles were destroyed, and approximately 2,200 researchers became redundant.
United States Special Forces and the CIA also had an interest in biological warfare, and a series of special munitions was created for their operations. The covert weapons developed for the military (M1, M2, M4, M5, and M32 - or Big Five Weapons) were destroyed in accordance with Nixon's executive order to end the offensive program. The CIA maintained its collection of biologicals well into 1975 when it became the subject of the senate Church Committee.
 The BWC (1972) and after
In 1972, the United States signed the Biological and Toxic Weapons Convention, which banned the "development, production and stockpiling of microbes or their poisonous products except in amounts necessary for protective and peaceful research." By 1996, 137 countries had signed the treaty; however it is believed that since the signing of the Convention the number of countries capable of producing such weapons has increased.
The Soviet Union continued research and production of offensive biological weapons in a program called Biopreparat, despite having signed the convention. The United States had no solid proof of this program until Dr. Vladimir Pasechnik defected in 1989, and Dr. Kanatjan Alibekov, the first deputy director of Biopreparat defected in 1992.
During the closing stages of the Rhodesian Bush War, the Rhodesian government resorted to biological warfare. Watercourses at several sites close to the Mozambique border were deliberately contaminated with cholera and the toxin Sodium Coumadin, an anti-coagulant commonly used as the active ingredient in rat poison. Food stocks in the area were contaminated with anthrax spores. These biological attacks had little impact on the fighting capability of ZANLA, but caused considerable distress to the local population. Over 10,000 people contracted anthrax in the period 1978 to 1980, of whom 200 died. The facts about this episode became known during the hearings of the South African Truth and Reconciliation Commission during the late 1990s.
After the 1991 Persian Gulf War, Iraq admitted to the United Nations inspection team to having produced 19,000 liters of concentrated botulinum toxin, of which approximately 10,000 L were loaded into military weapons; the 19,000 liters have never been fully accounted for. This is approximately three times the amount needed to kill the entire current human population by inhalation, although in practice it would be impossible to distribute it so efficiently, and, unless it is protected from oxygen, it deteriorates in storage.
According to the U.S. Office of Technology Assessment (since disbanded) 17 countries were believed to possess biological weapons in 1995: Libya, North Korea, South Korea, Iraq, Taiwan, Syria, Israel, Iran, China, Egypt, Vietnam, Laos, Cuba, Bulgaria, India, South Africa, and Russia.
 21st century
On September 18, 2001 and for a few days after, several letters were received by members of the U.S. Congress and media outlets containing anthrax spores: the attack sickened 17 people and killed five others. The identity of the perpetrator remained unknown until 2008, when a primary suspect was named. See 2001 anthrax attacks.
Today, according to the U.S. Department of Defense, more than ten countries are suspected to have continuing offensive BW programs, including Russia, Israel, China, Iran, Syria and North Korea. Offensive BW programs in Iraq were dismantled after the first Gulf War (1990-91). Libya dismantled and disavowed its BW program in 2003.
 List of historical BW programs by country
* United States biological weapons program
* United Kingdom and weapons of mass destruction#Biological weapons
* Soviet biological weapons program
* Japan: Special Research Units
* Iraqi biological weapons program (see also Iraq and weapons of mass destruction)
* South Africa and weapons of mass destruction#Biological and chemical weapons