The Black Death was one of history’s most destructive and transformative disasters. Was it caused by an intentional act of biological warfare?
A modern-day plague
The United States was under attack. In New York City, the twin towers of the World Trade Centre had been destroyed. In Washington D.C., a gaping hole was punched into the western side of Pentagon. Americans asked themselves ‘what was next’?
The answer would arrive in the post. Envelopes arrived at the offices of newspapers, television stations and politicians. They contained a brown powder. It was anthrax, a terrifying and lethal bacterial disease.
The attacks resulted in the deaths of five people. It was a doomsday scenario that worried emergency services and terrified the general public. Biological warfare had come to our cities.
Did the public’s concern over biological attack stems from a primordial fear of plague? Some of humanity’s greatest disasters sprang from the spread of this highly infectious disease.
In the Sixth-Century CE, the Plague of Justinian killed the last hope of reunifying the Roman Empire. European diseases ravaged native populations across the Americas in the decades following Columbus’s voyage.
The First World War was followed by a horrifying coda in form of an influenza pandemic. The Spanish Flu killed far more people than the conflict.
These were all natural disasters rather than manmade biological attacks. But was the most terrifying outbreak of plague started deliberately?
The Black Death as its disastrous consequence
Microbiologist Mark Wheelis thinks it is possible. He highlights the Siege of Caffa (sometimes written as Kaffa) in 1346. For some, this was the moment that plague moved from Asia to Europe. If the records are to be believed, this:
“should be recognized as the site of the most spectacular incident of biological warfare ever, with the Black Death as its disastrous consequence.” 
Gabriel de Mussis was a notary from Piacenza in Italy. He wrote a vivid account of the arrival of plague in his Istoria de Morbo (History of the Disease). The outbreak spread from port to port. First, it overran Sicily and then the Italian mainland. Europe’s trading lifelines became deadly highways for the transmission of the Black Death.
Most historians agree that the plague started in Asia. Given its virulence, how did it survive the long ocean voyages to reach Europe? According to de Mussis’ account, it was the combination of biological warfare and trade.
A mysterious illness which brought sudden death
De Mussis recounts how the plague ravaged lands so far away they were almost mythical:
“In 1346, in the countries of the East, countless numbers of Tartars and Saracens were struck down by a mysterious illness which brought sudden death. Within these countries broad regions, far-spreading provinces, magnificent kingdoms, cities, towns and settlements, ground down by illness and devoured by dreadful death, were soon stripped of their inhabitants.”
Meanwhile, intermittent conflict between Crimean Tartars and Christian merchants flared into warfare. Europeans poured into the Genoese port of Caffar. Soon, this outpost attracted the attentions of the Tartars, who laid siege. Few things were more conducive to the spread of infectious disease than conditions in a 14th century encampment. De Mussis picks up the narrative:
“But behold, the whole army was affected by a disease which overran the Tartars and killed thousands upon thousands every day. It was as though arrows were raining down from heaven to strike and crush the Tartars’ arrogance.
All medical advice and attention was useless; the Tartars died as soon as the signs of disease appeared on their bodies: swellings in the armpit or groin caused by coagulating humours, followed by a putrid fever.”
The Black Death had struck, destroying the Tartar armies. It raised the tantalizing prospect that Caffar was saved by divine intervention. Unfortunately for the Genoese, the Tartars made one last attack:
“The dying Tartars, stunned and stupefied by the immensity of the disaster brought about by the disease, and realizing that they had no hope of escape, lost interest in the siege. But they ordered corpses to be placed in catapults and lobbed into the city in the hope that the intolerable stench would kill everyone inside.”
Caffar’s residents would have survived a bad smell, no matter how putrid the air or unpleasant the prospect of raining corpses. But they couldn’t withstand the plague. The Genoese:
“fell victim to sudden death after contracting this pestilential disease, as if struck by a lethal arrow which raised a tumor on their bodies.”
Some boats were bound for Genoa, others went to Venice
For many of the city’s inhabitants, there was only one thing to do – go home. Ships sailed from the Black Sea carrying the Black Death. They headed to Italy and, almost inevitably:
“among those who escaped from Caffa by boat were a few sailors who had been infected with the poisonous disease. Some boats were bound for Genoa, others went to Venice and to other Christian areas.
When the sailors reached these places and mixed with the people there, it was as if they had brought evil spirits with them: every city, every settlement, every place was poisoned by the contagious pestilence, and their inhabitants, both men and women, died suddenly.”
As Professor Wheelis notes, de Mussis: “makes two important claims about the siege of Caffa and the Black Death that plague was transmitted to Europeans by the hurling of diseased cadavers into the besieged city of Caffa and that Italians fleeing from Caffa brought it to the Mediterranean ports.”
Only one of several streams of infected ships and caravans
So, was a deliberate act of biological warfare responsible for the death of between 30-60% of Europe’s total population? Professor Wheelis’s conclusion is clear – no. He believes that it is “unlikely that the attack had a decisive role in the spread of plague to Europe.”
Why? Because European trade routes were more extensive than a single link to Crimea. Professor Wheelis notes that: “much maritime commerce probably continued throughout this period, from other Crimean ports. Overland caravan routes to the Middle East were also unaffected.”
So, rather than being the sole source of plague “refugees from Caffa would most likely have constituted only one of several streams of infected ships and caravans leaving the region.”
Do you want to know more?
The Black Death is a compelling and terrifying subject. I came across this story when listening to Professor Dorsey Armstrong’s Great Courses series of lectures The Black Death: The World’s Most Devastating Plague (link). I can’t recommend it enough – it is a lucid, broad and fascinating introduction to one of Europe’s most important historical events.
 Wheelis, Mark. “Biological Warfare at the 1346 Siege of Caffa.” Emerg. Infect. Dis. Emerging Infectious Diseases 8, no. 9 (2002): 971-75 (link)