Laudator Temporis Acti

Kyle Harper, The Fate of Rome: Climate, Disease, and the End of an Empire (Princeton: Princeton University Press, 2017), p. 18:

The centuries of later Roman history might be considered the age of pandemic disease. Three times the empire was rocked by mortality events with stunning geographical reach. In AD 165 an event known as the Antonine Plague, probably caused by smallpox, erupted. In AD 249, an uncertain pathogen swept the territories under Roman rule. And in AD 541, the first great pandemic of Yersinia pestis, the agent that causes bubonic plague, arrived and lingered for over two hundred years. The magnitude of these biological catastrophes is almost incomprehensible. The least of the three pandemics, by casualty count, was probably the mortality known as the Antonine Plague. We will argue that it carried off perhaps seven million victims. That is considerably lower than some estimates. But the bloodiest day of battle in imperial history was the rout of the Romans at Adrianople, when a desperate force of Gothic invaders overran the main body of the eastern field army. At most twenty thousand Roman lives were lost on that baleful day, and while it magnified the problem that these were soldiers, the lesson of the comparison is all the same: germs are far deadlier than Germans.