History of the Peloponnesian War

In the very beginning of summer the Peloponnesians and their confederates, with two-thirds of their forces as before, invaded Attica under the conduct of Archidamus the son of Zeuxidamas, king of Lacedaemon, and after they had encamped themselves, wasted the country about them.

They had not been many days in Attica when the plague first began amongst the Athenians, said also to have seized formerly on divers other parts, as about Lemnos and elsewhere; but so great a plague and mortality of men was never remembered to have happened in any place before.

For at first neither were the physicians able to cure it through ignorance of what it was but died fastest themselves, as being the men that most approached the sick, nor any other art of man availed whatsoever. All supplications to the gods and enquiries of oracles and whatsoever other means they used of that kind proved all unprofitable; insomuch as subdued with the greatness of the evil, they gave them all over.