The Great Mortality: An Intimate History of the Black Death, the Most Devastating Plague of All Time

by John Kelly

when I first began thinking about writing a book on the plague, I had in mind plague in the generic sense of a major outbreak of epidemic disease, and I was looking ahead to the twenty-first century, not backward toward the fourteenth.

Its subject is an outbreak of a particular infectious disease in a particular time and place. Seven hundred years after the fact, what we call the Black Death—and what medieval Europeans called the Great Mortality, and medieval Muslims, the Year of Annihilation—remains the greatest natural disaster in human history. Apocalyptic in scale, the Black Death affected every part of Eurasia, from the bustling ports along the China Sea to the sleepy fishing villages of coastal Portugal, and it produced suffering and death on a scale that, even after two world wars and twenty-seven million AIDS deaths worldwide, remains astonishing. In

in many places the plague claimed a third of the population;

in others, half the population; and in a few regi...

The affliction was not limited to humans. For a brief moment in the middle of the fourteenth century, the words of Genesis 7—“All flesh died that moved upon the earth”—seemed about to be realized. There are accounts of dogs, cats, birds, camels, even of lion...

By March of 1348 much of central and northern Italy was or soon would be infected, including Genoa, Florence, and Venice, where gondolas slipped through wintery canals to collect the dead; by spring the plague was in Spain, southern France, and the Balkans, where one contemporary reports that packs of wolves came down from the hills to attack the living and feed on the dead.

Most modern historians believe that what we call the Black Death originated somewhere in inner Asia, then spread westward to the Middle East and Europe and eastward to China along the international trade routes.

Plague is the most successful example of oimmeddam in recorded history. Worldwide, the disease has killed an estimated 200 million people, and no outbreak of plague has claimed as many victims or caused as much anguish and sorrow as the Black Death. According to the Foster scale, a kind of Richter scale of human disaster, the medieval plague is the second greatest catastrophe in the human record. Only World War II produced more death, physical destruction, and emotional suffering,

widely accepted mortality figure is 33 percent.* In raw numbers that means that between 1347, when the plague arrived in Sicily, and 1352, when it appeared in the plains in front of Moscow, the continent lost twenty-five million of its seventy-five million inhabitants.

But in parts of urban Italy, eastern England, and rural France, the loss of human life was far greater, ranging from 40 to 60 percent. The Black Death was particularly cruel to children and to women, who died in greater numbers than men, probably because they spent more time indoors, where the risk of infection was greater, and cruelest of all to pregnant women, who invariably gave birth before dying.

but between 1200 and 1393 the population of the country fell 50 percent, from about 123 million to 65 million. Today a demographic disaster on the scale of the Black Death would claim 1.9 billion lives.

That said, tree ring data indicates that the early fourteenth century was one of the most severe periods of environmental stress in the last two thousand years—perhaps due to unusual seismic activity in the world’s oceans.

Social and demographic conditions are also risk factors in plague. Like other infectious illnesses, the disease requires a minimum population base of four hundred thousand people to sustain itself.

A principal vector in human plague, the black rat—Rattus rattus—feeds on human refuse and garbage, so the filthier a society’s streets and homes and farms, the larger its plague risk.

Since the flea is an even more critical disease vector, personal sanitation matters as well; people who wash rarely are more attractive to an infected flea than those who wash regularly. Humans who live with farm animals are also at greater risk because they are exposed to more rats and fleas; and if a population lives in homes with permeable roofs and walls, the risk is even greater.

From Caffa to the jungles of Vietnam,* war has also been an important predisposing factor in human plague. War creates human remains and refuse, which attract rats; filthy bodies, which attract fleas; and stresses, which can lower immune system function. Marching soldiers and cavalry also help to make a pestilence more mobile. The historical evidence suggests that the existence of only a few of these conditions is not enough to ignite a pandemic, or major outbreak of plague.

The era that was once called the Dark Ages and is now referred to (less judgmentally, if no more accurately) as the Early Middle Ages also had several conditions associated with plague, including widespread violence, disorder, malnutrition, and filth—if early medieval Europeans washed or changed their clothes more than once or twice a year, it was the best-kept secret in Christendom.

Between 1315 and 1322 the continent was lashed by waves of torrential rain, and by the time the sun came out again in some places 10 to 15 percent of the population had died of starvation. In Italy especially, malnutrition remained widespread and chronic, right until the eve of the plague.

Bubonic plague is the most survivable of the three forms of the disease. Untreated, it has a mortality rate of about 60 percent. Pneumonic is the second type of plague, and—uniquely—it can spread directly from person to person.

The “coughing plague” is extremely lethal. If it goes untreated, the mortality rate in its victims is between 95 and 100 percent. No one survives untreated septicemic plague, the third form of the disease. The shocklike movement of massive amounts of plague bacilli directly into the blood system creates such enormous toxicity that even insects normally incapable of transmitting Y. pestis, such as body lice, can become disease vectors. During one outbreak of septicemic plague in the early twentieth century, the average survival time from onset of symptoms to death was 14.5 hours.

“Great Mortality,” or, more colloquially, the “Big Death.”

In the three and a half years it took Y. pestis to complete its circle of death, plague touched the life of every individual European: killing a third of them, leaving the other two-thirds grieving and weeping. Here is the story of that epic tragedy.

The Great Famine, the collective name for the crop failures, was a tremendous human tragedy. A half-million people died in England; perhaps 10 to 15 percent of urban Flanders and Germany perished; and a large but unknowable segment of rural Europe also succumbed.

“The one who was poorly nourished by unsubstantial food fell victim to the merest breath of the disease,” he observed.

where Black Death losses were moderate or light, despite a recent history of famine. Critics also point to another inconsistency. In the years between the Great Famine and the plague, diets actually improved somewhat. If people were eating better, they ask, how could nutrition have been a predisposing factor in the Black Death?

More centrally, the profound malnutrition of the Great Famine years may have left millions of Europeans more vulnerable to the Black Death.

“By inference,” declares Professor Jordan, author of a study on the Great Famine, “the horrendous mortality of the Black Death should reflect the fact that poor people who were in their thirties and forties during the plague had been young children in the period 1315–1322 and were developmentally more susceptible to the disease than those who had been adults during the Famine or were born after the Famine abated.”

the black rat usually travels by night, builds an escape route in its den, and reconnoiters carefully. This last behavior seems, at least in part, learned. During a foraging expedition, one young rat was observed taking a reconnaissance lesson from its mother. It would scamper ahead a few feet, stop until the mother caught up, then wait as she examined the floor ahead. Only after receiving a reassuring maternal nudge would the young rat advance. Rats also have another rather unusual, humanlike trait: they laugh. Young rats have been observed laughing—or purring, the rodent equivalent of laughter—when playing and being tickled. Rattus is, by nature, a very sedentary animal—usually. A city rat may wonder what lies on the other side of the street, but studies show it won’t cross the street to find out.

Urban rats live their entire lives in a single city block. The rural rat’s range is a not much larger—a mile or so. However, if Rattus were phobic about long-distance travel, it would still be an obscure Asian oddity, like the Komodo dragon lizard. Rats do travel, and often for reasons that highlight the role of trade and ecological disaster in plague.

The Black Death’s visit to Florence is unusually well documented. We know that the mortality claimed roughly fifty thousand lives, a death rate of 50 percent in a city of about a hundred thousand.

All along the coastal southwest in the black autumn of 1348, the living gathered in the rain to bury the dead.

Some historians believe the plague in London may have followed the pattern in Avignon—pneumonic in winter, bubonic in the spring and summer—though firm evidence on this point is lacking.

The plague also claimed twenty-seven monks at Westminster Abbey, and the number would have been twenty-eight had not the hot-tempered, disagreeable Abbot Simon de Bircheston fled to his estate in Hampshire, to no avail. During its sweep through coastal England, the plague stopped in Hampshire and killed him.

On the last day of 1348, a winter flood submerged the western parishes of York; then, a few days before Passion Sunday, an earthquake rocked the Abbey of Meaux, also in Yorkshire. If modern experience is any guide, both events may have facilitated Y. pestis’s work by disrupting rodent habitats and sending local rats fleeing toward human settlements.

One historian puts the death rate among the Anglo-Irish at 35 to 45 percent; the native Irish probably suffered less, though how much less is unclear. Whatever their death rate, there was more than enough suffering to go around in Ireland in 1348 and 1349.

The Great Mortality occasioned one of the most vicious outbreaks of anti-Semitic violence in European history.

However, as a general proposition, it is fair to say that almost no area of Europe entirely escaped the Black Death. In addition to blanketing the continent from east to west, by 1350, the plague would also cover it from north to south.

Barely eleven summers passed between the Black Death and the pestis secunda, as the second outbreak of plague was called. The new epidemic, which began in 1361, marked the beginning of a long wave of plague death that would roll on through more than three centuries.

Horrific as a century of unremitting death had been, Europe emerged from the charnel house of pestilence and epidemic cleansed and renewed—like the sun after rain.