The Plague of Athens (429-426 BCE) struck the city, most likely, in 430 BCE before it was recognized as an epidemic and, before it was done, had claimed between 75,000-100,000 lives. Modern-day scholars believe it was most likely an outbreak of smallpox or typhus, but bubonic plague is still considered a possibility.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/1535/thucydides-on-the-plague-of-athens-text--commentar/.