The Black Death

Mortality Rates During the Black Death

Establishing precise mortality rates for the Black Death is one of the most challenging tasks in medieval historiography. Contemporary sources provide figures that range from the plausible to the fantastical, and modern scholars have reached widely different conclusions depending on which sources they privilege and which methodologies they employ. What is certain is that the pandemic killed a proportion of Europe’s population that has no parallel in recorded history.

Contemporary Estimates

Medieval chroniclers, confronted with death on an unprecedented scale, reached for numbers that expressed the enormity of the catastrophe rather than its statistical precision. Boccaccio claimed that 100,000 people died in Florence between March and July 1348 — a figure that would exceed the city’s entire pre-plague population of approximately 90,000 to 100,000. The Sienese chronicler Agnolo di Tura estimated 80,000 deaths in Siena and its territory. The French chronicler Jean de Venette reported that 800 died daily at the Hôtel-Dieu in Paris at the epidemic’s peak.

These figures are not reliable as precise statistics. Medieval chroniclers had no access to systematic mortality data, and their numbers were often rounded, exaggerated, or derived from hearsay. However, they are valuable as indicators of the perceived scale of the catastrophe. When multiple independent sources describe mortality in similar terms — as a third, a half, or even more of the population — the convergence suggests that the reality was indeed catastrophic, even if the specific numbers are inflated.

Modern Estimates: The Range of Debate

Modern estimates of Black Death mortality fall into several broad categories. The most conservative estimates, associated with the historian Josiah C. Russell, place overall European mortality at roughly twenty to twenty-five percent. Against a European pre-plague population that modern scholarship generally puts at around 70 to 80 million, such a rate implies on the order of 20 million deaths; Russell’s low figures have since been widely criticised as underestimates. These estimates are based on the analysis of manorial records, tax assessments, and ecclesiastical documents, primarily from England and France.

More recent scholarship has argued for higher figures. The Norwegian historian Ole J. Benedictow, in his comprehensive survey of the evidence, has estimated that the Black Death killed approximately sixty percent of Europe’s population — roughly 50 million deaths. Benedictow’s estimate is based on a region-by-region analysis of the available evidence, including sources that Russell and other conservative scholars had not fully considered.

Most scholars now accept a range of thirty to fifty percent for overall European mortality, with significant regional variation. The debate continues, driven by new evidence from archaeological excavations, DNA studies, and the reanalysis of existing documentary sources.

Regional Variation

Mortality rates varied enormously across Europe. The cities of Italy, where the pandemic struck first and hardest, may have lost forty to sixty percent of their populations. Florence, Siena, Venice, and Pisa all suffered devastating losses. In England, manorial records suggest mortality among tenants of forty to fifty percent, with some manors losing all their tenants. Norway may have lost as much as sixty percent of its population, based on the evidence of farm abandonment.

Other regions appear to have suffered less. Bohemia and Poland may have experienced lower mortality, though the evidence is uncertain. Milan, which implemented aggressive quarantine measures, appears to have escaped relatively lightly compared to other Italian cities. Isolated communities in mountainous regions — the Pyrenees, the Alps, the Scottish Highlands — sometimes avoided the initial wave entirely, only to be struck by subsequent outbreaks.

Urban vs. Rural Mortality

The relationship between urban and rural mortality during the Black Death is complex. Cities, with their crowded conditions, poor sanitation, and dense rat and flea populations, provided ideal conditions for the spread of bubonic plague. The impact on urban populations was severe, and many cities lost a third to half their inhabitants.

However, rural communities were not immune. The density of rural settlement in much of Europe, the close proximity of humans to livestock and rodents, and the movement of people and goods along trade routes all facilitated the spread of the disease. The impact on peasants and rural communities was devastating, and the evidence of farm abandonment across Europe testifies to the severity of rural mortality.

Some scholars have argued that rural mortality was actually higher than urban mortality in certain regions, because rural populations were more exposed to the initial epizootic among rodents and had less access to medical care. The evidence is mixed, and the pattern likely varied by region and local circumstances.

Social Class and Mortality

The Black Death did not respect social boundaries — it killed kings and peasants, clergy and laity, rich and poor. However, mortality was not evenly distributed across social classes. The wealthy had several advantages: they could flee infected cities for rural estates, they lived in better-built houses that were less permeable to rats, and they had access to the best available medical treatments. The impact on the nobility was significant but generally less severe than on the lower classes.

The poor, who could not afford to flee and who lived in crowded, rat-infested housing, bore the brunt of the epidemic. The impact on peasants and urban labourers was devastating, and the mortality among these groups was likely higher than the overall average. Clergy, who administered last rites to the dying and were therefore in close contact with infected individuals, also suffered disproportionately high mortality.

Age and Sex Patterns

The age and sex patterns of Black Death mortality are difficult to establish from documentary sources, which rarely recorded the age or sex of the dead with precision. However, archaeological evidence from plague cemeteries — particularly the East Smithfield cemetery in London — has provided some insights.

Analysis of skeletal remains from East Smithfield suggests that the plague did not kill indiscriminately. Individuals who were already in poor health — as indicated by skeletal markers of stress, malnutrition, or chronic disease — were more likely to die. This finding supports the hypothesis that the Black Death was a “selective” killer, disproportionately affecting those whose immune systems were already compromised.

The question of whether the plague killed men and women in equal proportions remains debated. Some sources suggest that men were more heavily affected, possibly because they were more likely to travel and to be exposed to infection through commercial and military activities. Other sources suggest no significant sex difference. The evidence is insufficient to resolve this question definitively.

The Cumulative Effect of Repeated Outbreaks

The mortality of the initial Black Death of 1347–1352 was compounded by the recurring waves of plague that struck Europe at regular intervals for the following three centuries. The pestis secunda of 1361–1362 killed a significant proportion of those who had survived the first outbreak. Subsequent epidemics in the 1370s, 1380s, and beyond prevented demographic recovery and ensured that the cumulative mortality of the Second Pandemic far exceeded that of the initial outbreak alone.

The effect of repeated plague on population structure was profound. Each wave disproportionately affected children and young adults — those who had been born since the last outbreak and had no acquired immunity. This pattern created a “demographic trap” in which each generation was smaller than the last, preventing the population from recovering to pre-plague levels for centuries.

Methodological Challenges

The estimation of Black Death mortality is fraught with methodological difficulties. Medieval sources are uneven in their coverage: some regions (England, Tuscany) are relatively well documented, while others (Eastern Europe, the Balkans) have very sparse evidence. The types of sources available — manorial court rolls, tax assessments, ecclesiastical records, chronicles — each have their own biases and limitations.

Manorial records, for example, record the deaths of tenants (adult male heads of household) but not necessarily the deaths of their wives, children, or servants. Tax records may undercount the poor, who were often exempt from taxation. Ecclesiastical records may overrepresent the clergy and underrepresent the laity. Chroniclers’ figures are often rounded or exaggerated.

Modern scholars have employed a variety of methods to address these challenges: statistical analysis of surviving records, comparison of pre-plague and post-plague tax assessments, analysis of archaeological evidence from plague cemeteries, and modelling based on the known epidemiology of plague. Each method has strengths and weaknesses, and the resulting estimates vary accordingly.