18. Killing at its peak as many as 2,000 people per day in the city of Rome, the Antonine Plague devastated the Roman Empire during the 2nd century
The Antonine Plague, also known as the Plague of Galen, was an ancient pandemic that devastated the Roman Empire between 165 and 180 CE. Imported into Roman territory from the Near East by soldiers returning from military campaigns abroad, the initial outbreak of the plague is believed to have been responsible for the death of Roman Emperor Lucius Verus, co-ruler with Marcus Aurelias, in 169. After subsiding for a few years, in 178 the plague exploded once again; across this collective time period, it is estimated the epidemic was responsible for the deaths of approximately five million.
Killing at its peak 2,000 people per day in Rome, in addition to as much as one-third of the population in certain regions of the empire, the disease carried a mortality rate of roughly twenty-five percent. The prolonged nature of the plague resulted in crippling consequences to Roman military effectiveness, with major offensives in Germania postponed due to a lack of soldiers. The precise nature of the plague is uncertain, with Galen describing the condition as resulting in fevers, diarrhea, pharyngitis, as well as skin lesions and pustules. Modern scientific opinion has generally coalesced around a consensus that the Antonine Plague was a form of smallpox.