History of the Peloponnesian War

Thucydides

Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.

Accordingly Hagnon took his fleet back to Athens, having lost by the plague in about forty days one thousand and fifty out of a total of four thousand hoplites; but the soldiers of the former expedition remained where they were and continued the siege of Potidaea.

After the second invasion of the Peloponnesians the Athenians underwent a change of feeling, now that their land had been ravaged a second time while the plague and the war combined lay heavily upon them.