The Black Death
In the late 1320s, a particularly virulent form of plague erupted in the Gobi desert of Mongolia. Within a generation, it had spread east to China where, in 1351, chroniclers claimed that it had killed two-thirds of the population. It was also carried by Mongol nomads along the trade routes west.
According to sailors' stories reported by the notary Gabriele de' Mussis, merchants from the Italian city of Genoa, who in 1346 had travelled to the Black Sea port of Caffa (now Feodosia) in the Crimea, came under siege from the Tartar army of a Kipchak khan called Janibeg. When plague broke out among his troops, Janibeg ordered the survivors to load their comrades' corpses on to catapults and toss them over Caffa's walls. As the horrific rain of cadavers fell, the plague entered Caffa. When the Genoese fled, they carried with them into Europe what came to be called the Black Death.
The Black Death got this name as a result of the internal bleeding that occurs in all three types of the disease in humans. This causes large black bruises to appear on the skin. For more medical information on the disease, see What is plague?.
Along the circuitous trade routes of the 14th century, the plague cut short the lives of millions. In Constantinople in 1347, it struck down thousands of Byzantines, including Andronicus, son of the Greek emperor John VI Cantacuzenus. In Cairo in 1348, up to two-fifths of the population died. In the Nile Delta village of Bilbais, corpses were piled so high along the roads that bandits took to hiding behind them during ambushes.
Aswan, Antioch, Damascus, Jerusalem, Tunis and even Mecca followed – by 1349, one-third of the Islamic world had perished.
Marching into Italy
In the latter part of 1347, death marched into Italy via Genoa (with the returning merchants) and Pisa and ravaged its crowded cities. At Siena, one mourner wrote:
They died by the hundreds, both day and night, and all were thrown in … ditches and covered with earth. And as soon as those ditches were filled, more were dug. And I, Agnolo di Tura … buried my five children with my own hands … And so many died that all believed it was the end of the world.
The humanist Giovanni Boccaccio witnessed the Black Death in Florence and told what he had seen in the introduction to his Decameron:
Such was the cruelty of heaven and, to a great degree, of man that, between March  and the following July, it is estimated that more than 100,000 human beings lost their lives within the walls of Florence, what with the ravages attendant on the plague and the barbarity of the survivors towards the sick.
France and Spain
The pestilence spread to France. At Marseilles, 50-60% died. At Montpelier, only 7 of 140 Dominican friars survived. At Avignon, the great surgeon Guy de Chauliac advised Pope Clement VI to flee, but stayed himself and caught the disease – amazingly he recovered after six weeks.
In 1349, the army of Alfonso XI of Castile was besieging Gibraltar when the Black Death struck both sides. Alfonso refused to leave his troops and died – the only crowned head of Europe to succumb to the plague.
The Black Death arrived in England, at Weymouth, in June 1348 and quickly spread east to devastate London. The countryside was also harshly affected. In all, about two million Britons perished – half the population.
The plague reached Germany in June 1349, Scandinavia and northern Scotland the following December, and Russia at the end of 1350. Then, having killed perhaps one-third or more of the people of Europe, for some inexplicable reason the pandemic halted.
Making sense of it all
According to the Church, the Black Death was God's punishment for the sinfulness of humanity. Medieval doctors, however, tended to blame a 'pestilential atmosphere' caused either by a planetary conjunction or by earthquakes and volcanic eruptions that had occurred before the disease appeared.
Doctors tried every possible cure and preventative. Gentilis of Foligno wrote that huge fires of aromatic woods should be lit to purify the atmosphere. The University of Paris medical faculty agreed, and stressed that 'olive oil, as an article of food, is fatal … Bathing is injurious. Men must preserve chastity as they value their lives.'
Others believed that the air had become 'stiff' and had to be broken up by loud noises. So bells were rung, guns were fired and birds were released to fly around rooms.
Eventually, doctors came to recognise the principle of contagion, or at least to act upon it. In Milan, they advised the reigning Viscontis to wall up houses in which victims were found, even if they also immured healthy family members. This drastic measure seems to have paid off, however: Milan lost less than 15% of its population, the lowest death rate in Italy.
Fleeing the Black Death simply spread it further, and doctors ran away like everyone else. In Venice, this led to surgeons being allowed to practise like physicians, to make up the numbers.
But physicians and surgeons alike found that nothing they did made any difference. As Guy de Chauliac was to write: 'The disease was most humiliating for the physicians, who were unable to render any assistance.'
Mass hysteria was also a characteristic of the Black Death. In 1348, the Brotherhood of the Flagellants – whose aim was to induce God to stop punishing the world with the plague – sprang up. Ominously, this bizarre sect was particularly common in Germany.
Large groups would march from town to town, stripped to the waist and whipping themselves with metal-tipped scourges. Frequently, though, they carried the infection with them.
Flagellants and anti-Semitism
Much more serious was the persecution of the Jews. Claims that they had started the plague by poisoning wells were fuelled by the confessions, at a trial in the Swiss town of Chillon in September 1348, of Jews who had been tortured.
In Basel, all Jews were penned up in a wooden building and burned alive. This was a practice that found favour in Germany, although simple slaughter also sufficed – at least 2,000 Jews were murdered in Strasbourg, 12,000 in Mainz, 600 in Brussels.
In July 1349, the Flagellants led the people of Frankfurt to the Jewish quarter for a wholesale massacre. Not until the appalling Holocaust of World War II would the Jews again suffer such persecution.
The truth revealed
Only in 1894, during an epidemic in Hong Kong, was the plague bacillus Pasteurella pestis (now known as Yersinia pestis) identified and found to be a disease of black rats and other rodents, spread by their fleas. When all the rats died, the fleas would look for new hosts: humans. The plague bacillus is extremely virulent – laboratory mice die after being infected with three bacilli … and fleas can disgorge up to 24,000 in each bite.
In 1932, with the creation of sulphonamide drugs, there was finally an effective treatment for the plague. Yet, within 50 years, there were reports – persistent, though unconfirmed – that a strain of plague bacillus resistant to all medical and control measures had been developed for bacteriological warfare by the US Army.