The Black Death arrived on European shores in 1348. By 1350, the year it retreated, it had felled a quarter to half of the region’s population. In 1362, 1368, and 1381, it struck again—as it would periodically well into the 18th century.
The contemporary Sienese chronicler, Agnolo di Tura del Grasso, described its terror. A victim first experiences flu-like symptoms, and then sees a “swell beneath their armpits and in their groins.” Agnolo himself buried his five children with his own hands. He also lost his wife.
The plague hit hard and fast. People lay ill little more than two or three days and died suddenly….He who was well one day was dead the next and being carried to his grave,” writes the Carmelite friar Jean de Venette in his 14th century French chronicle. From his native Picardy, Jean witnessed the disease’s impact in northern France; Normandy, for example, lost 70 to 80 percent of its population. Italy was equally devastated. The Florentine author Boccaccio recounts how that city’s citizens “dug for each graveyard a huge trench, in which they laid the corpses as they arrived by hundreds at a time, piling them up tier upon tier as merchandise is stowed on a ship.
Trade was to Blame
Growing stability in Europe in the late middle ages made possible extensive trade between East and West and within Europe itself. Italian city-states such as Venice and Genoa had trading ports in the eastern Mediterranean and the Black sea—trade that made these cities among the wealthiest cities in Europe. Most historians today generally agree that the plague was likely spread through Eurasia via these trade routes by parasites carried on the backs of rodents. The bacterium Yersinia pestis (and not all historians agree this was the culprit) likely traveled from China to the northwestern shores of the Caspian Sea, then part of the Mongol Empire and by the spring of 1346, Italian merchants in the Crimea, specifically the Genoese-dominated city of Kaffa (today Feodosiya in the Ukraine) brought the disease west. Rats carrying infected fleas boarded ships bound for Constantinople (today Istanbul in Turkey), capital of the Byzantine Empire. Inhabitants there were sickened by the plague by early July.
From these Greek-speaking lands, the plague spread to North Africa and the Middle East with terrible consequences; by autumn 1347, it had reached the French port of Marseilles and progressed both north and west. By early November, the Italian city-states of Genoa, Pisa, and Venice—commercial hubs for European trade—had been struck.
Most of the rest of Europe followed in short order. The disease spread along the active trade routes that northern Italian and Flemish merchants had developed. London and Bruges then communicated the disease via busy shipping lanes to the Nordic countries and the Baltic region (aided by a trading partnership known as the Hanseatic League). Western crusaders seeking to attack the Holy Land prompted innovations in shipbuilding and these larger and faster ships carried large quantities of goods over extensive trade networks— but they also carried the deadly pathogen.
"God is deaf nowadays and will not hear us"
The pandemic ended up killing approximately half of  Europe’s population, indiscriminate of people’s wealth, social standing, or religious piety. Survivors “were like persons distraught and almost without feeling,” writes Agnolo, a despair echoed throughout Europe. “God is deaf nowadays and will not hear us. And for our guilt he grinds good men to dust,” wrote the late 14th century English cleric, William Langland, in his epic poem “Piers Plowman.”
With so many dead and dying, patterns that had kept medieval society stable were replaced by hostility, confusion, greed, remorse, abuse—and, at times, genuine caring. Contemporary chronicles tell of eruptions of violence, “Christians massacred Jews in Germany and other parts of the world where Jews lived, and many thousands were burned everywhere, indiscriminately,” wrote Jean de Venette, describing a ritualized attacks against Jews who became scapegoats.
Some Christians became more pious, believing that their piety might endear them to a God who they believed had sent the plague to punish them for their sins. Texts from this time describe Penitent pilgrims, at times flagellating themselves with whips, crowding the roads. Others reacted by assuming a no-holds-barred attitude toward life, giving “themselves over to pleasures: monks, priests, nuns and lay men and women all enjoyed themselvesEveryone thought themselves rich because he had escaped and regained the world,” according to Agnolo.
