Between 1347 and 1351, a bacterium called Yersinia pestis killed somewhere between thirty and sixty percent of the population of Europe — perhaps 25 million people. The same plague had already hollowed out parts of the Middle East and was working through China. It moved along the trade routes the Mongols had built, on rats, on fleas, on grain shipments, leaping from the Black Sea port of Caffa to Sicily, then up through Italy and France to England and Scandinavia within four years. There is no comparable mortality event in recorded history. Whole monasteries died in a week. Villages were abandoned and remained empty for centuries. Florence's chronicler Boccaccio, who set the Decameron among young people fleeing the plague, wrote that the survivors could no longer believe in the same God.
The economic aftershock is the part historians keep returning to. With a third of the workforce dead, the price of labour rose and the price of land fell — a brutal inversion of the medieval norm, where land was scarce and people were cheap. Across Europe, peasants suddenly had bargaining power they had not enjoyed for centuries. Wages in England roughly doubled, rents collapsed, and tenants who had been bound to a manor for generations simply walked to whichever lord paid most. When landlords tried to freeze wages and pin labourers in place by statute — the Statute of Labourers of 1351 — they could not enforce it against a depleted, mobile population, and the resentment fed into revolts like the English Peasants' Revolt of 1381 and the French Jacquerie of 1358. Serfdom in western Europe broke under the pressure and never recovered; in eastern Europe, where labour was even scarcer and towns weaker, lords tightened it instead into a 'second serfdom' — a fork whose divergent paths shaped the two halves of the continent into the modern era. The surviving lower classes ate more meat, wore better cloth, and rebelled more confidently. A century and a half later, the Malthusian population pressure that had been keeping Europe poor was gone, and the continent emerged into the Renaissance with a demographically lighter footprint, higher per-capita wealth, and capital looking for a use. The Black Death, by an irony its victims could never have appreciated, helped clear the runway for European modernity.
The plague is the canonical case study for how shocks reshape political economy — how a sudden change in the ratio of people to resources rewrites who holds power over whom. Every modern conversation about pandemics, labour shortages, wage spikes, and inequality — including the post-COVID one, when workers briefly regained leverage and 'the Great Resignation' echoed the medieval flight to better wages — is, knowingly or not, working in the shadow of 1347.