The Great Plague (1665-1666) was a massive outbreak of disease in England that killed 75,000 to 100,000 people, up to a fifth of London’s population. The disease was historically identified as bubonic plague, an infection by the bacterium Yersinia pestis, transmitted through fleas.
The 1665-1666 epidemic was on a far smaller scale than the earlier “Black Death” pandemic, a virulent outbreak of disease in Europe between 1347 and 1353. The Bubonic Plague was only remembered afterwards as the “great” plague because it was one of the last widespread outbreaks in England.
Although the disease causing the epidemic has historically been identified as bubonic plague and its variants, no direct evidence of plague has ever been uncovered. Some modern scholars suggest that the symptoms and incubation period indicate that the causal agent may have been a disease similar to a viral hemorrhagic fever. (Pictured above is a list of mortalities from the time of the plague.)