The Black Death: Europe’s First Contact with the Plague


By Dorsey Armstrong, Ph.D., Purdue University

In the middle of the 14th century, one of the most devastating events in human history wiped out half of Europe’s population. The most likely cause for this pandemic—the  Bubonic Plague, caused by the ​Yersinia Pestis bacterium—started in Asia and made its way west, south, northwest, and then looped around back east, tightening around the medieval European world like a noose.

A painting depicting people dying from the plague.
Medieval Europeans believed the plague was a punishment from God. (Image: Everett Collection/Shutterstock)

The Italian Peninsula—in its prime position extending down into the Mediterranean and connected to the European landmass—had been a center of trade for centuries.

However, Italy was far from unified at this point. In effect, it was a collection of city-states, each fiercely independent and with its own self-contained government, guild system, military, and economic interests.

This is a transcript from the video series The Black Death: The World’s Most Devastating Plague. Watch it now, on Wondrium.

The Golden Horde

In the year 1266, a group of Genoese traders and merchants established a center of trade at a place called Caffa (Feodosia today). This port city is on the Crimean Peninsula, on the Black Sea. To set up a trading center there, the Genoese had to enter into an agreement with the local rulers of that area—the Tatars, also called Mongols or the Golden Horde.

Caffa was critical for international trading. From the Italian Peninsula, Genoese and other merchants would move from the Mediterranean into the Aegean Sea; and from there, through the Dardanelles into the Sea of Marmara; then through the Bosporus into the Black Sea, where they could enter Caffa.

From there, they could move into the Sea of Azov. They also had established an outpost in the northeast corner of the Sea of Azov (called Tana back then). From Tana, they could extend their trade route both overland into the Middle East and along the Don River into Russia.

Hostilities with the Mongols

It was an extensive and profitable network, but relations between the Mongols and the traders were often tense. A historically important hostility took place in 1307 when Toqtai Khan arrested most of the Italian traders who were then in the Mongol capital of Sarai, and then he laid siege to Caffa.

Toqtai Khan was angry with Genoese merchants. They were purchasing Turkish slaves and later selling them to the Mamluk Sultanate. The Sultan trained the slaves as soldiers and would order them to fight on his behalf against the Golden Horde.

After initially resisting the Mongol siege, the Genoese eventually fled the city, but before they left, they set the whole city of Caffa on fire in an act of defiance.

Learn more about how the Black Death transformed the world.

The First Contact

A few years later, Toqtai’s successor, Öz Beg, invited the Genoese back, recognizing that there was profit to be had from their relationship. Öz Beg allowed the Genoese to expand their trade network. This, in turn, made them ever more eager to keep a firm hold on Caffa.

In 1343, there was what amounts to a street fight in Tana between Italian and Muslim populations of the city. Instead of dissipating, the violence escalated, and the forces of the new Mongol leader, Jani Beg, embarked on arresting the Genoese who were involved.

Biological Warfare?

The Genoese  decided to flee the city across the Sea of Azov, into the Black Sea, and took refuge in Caffa. Further escalating the conflict, Jani Beg decided to attack Caffa, and he laid siege to it off and on for two whole years.

Among the reasons the conflict lasted so long was because the Genoese and other inhabitants of the city were still able to move around and get limited supplies by sea. But then something totally unexpected happened.

Statues of two Mongol Warriors
Before retreating, Mongol forces loaded up their trebuchets with plague-infected corpses and launched them into the city. (Image: Julian Elliott/Shutterstock)

In 1345, Jani Beg’s forces were ravaged by the plague. The Mongol forces recognized that they were defeated and that the siege was over. But before they withdrew, they engaged in what microbiologist Mark Wheelis has described as “the most spectacular incident of biological warfare ever”—they loaded up their trebuchets with plague-infected corpses and launched them into the city.

Learn more about plague outbreaks of 1353-1666.

Historia de Morbo

This was the first contact between the European world and the plague. What happened in this time period informs the first-person account of Gabriele de’Mussi, who wrote one of the first accounts of the plague’s arrival in Europe in his book ​Historia de Morbo​.

De’Mussi was a lawyer in the Italian town of Piacenza, which was itself hard hit by the plague. He reminds readers of the vengeance and punishments of God, stating that God had warned Christians to give up their sinning ways, and because they did not listen, the Lord then sent the plague as punishment.

In a key passage, to which historians and scientists have turned to over the years to understand the nature of the plague, de’Mussi writes:

Oh God! See how the heathen Tartar races, pouring together from all sides, suddenly infested the city of Caffa and besieged the trapped Christians there for almost three years. But behold, the whole army was affected by a disease which overran the Tartars and killed thousands upon thousands every day.

Who All Got Affected?

All medical advice and attention were useless; the Tartars died as soon as the signs of disease appeared on their bodies: swellings in the armpit or groin caused by coagulating humors, followed by a putrid fever.

A key question concerning the plague transmission based on this account is why those in the city didn’t also get infected? If the plague was spread by rat fleas and the Mongol army was already infected, shouldn’t the plague had also afflicted the city?

Well, the Mongol army was not right up against the city walls, as they had set their encampment at least half a mile away from the city’s defensive walls. And, in the case of Caffa, it was too far for the infected rat population within the army to travel in order to get into the city.

Common Questions about Europe’s First Contact with The Black Death

Q: How did the Mongol army engage in biological warfare against the Genoese population of Caffa?

In 1345, before retreating, the Mongol forces loaded up their trebuchets with plague-ridden corpses and launched them into the city.

Q:  In Gabriele de’Mussi’s view, what really caused the plague?

Gabriele de’Mussi stated that God had warned Christians to give up their sinning ways. But because they did not listen, the Lord then sent the plague as punishment.

Q: Why wasn’t the plague introduced to the Caffa by rat fleas?

The Mongol army had set their encampment at least half a mile away from Caffa’s defensive walls. Some researchers argue it was too far for plague-carrying rats to infiltrate the city.

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