The bubonic plague remained a frequent visitor to the cities of Europe for centuries after the Black Death of the fourteenth century. Most of the time the disease remained dormant, but about once in a generation, another European city would experience the disease. In 1665 a plague epidemic struck London, then the economic and commercial capital of the British Isles and Europe. The plague had appeared in Holland two years earlier, yet despite a total ban on trade with the Low Countries by the English king Charles II, the disease made its way across the English Channel.

Science had made many important advances since the time of the Black Death, but no one yet guessed at the existence of the plague bacillus, now known as Yersinia pestis, nor did anyone have any idea how to prevent or treat the disease. The plague was...