History of the Peloponnesian War

During the whole time that the Peloponnesians were in Attica and the Athenians on the expedition in their ships, men kept dying of the plague both in the armament and in Athens. Indeed it was actually asserted that the departure of the Peloponnesians was hastened by fear of the disorder; as they heard from deserters that it was in the city, and also could see the burials going on.

Yet in this invasion they remained longer than in any other, and ravaged the whole country, for they were about forty days in Attica.

The same summer Hagnon, son of Nicias, and Cleopompus, son of Clinias, the colleagues of Pericles, took the armament of which he had lately made use, and went off upon an expedition against the Chalcidians in the direction of Thrace and Potidaea, which was still under siege. As soon as they arrived, they brought up their engines against Potidaea and tried every means of taking it,

but did not succeed either in capturing the city or in doing anything else worthy of their preparations. For the plague attacked them here also, and committed such havoc as to cripple them completely, even the previously healthy soldiers of the former expedition catching the infection from Hagnon's troops; while Phormio and the sixteen hundred men whom he commanded only escaped by being no longer in the neighborhood of the Chalcidians.

The end of it was that Hagnon returned with his ships to Athens, having lost one thousand and fifty out of four thousand heavy infantry in about forty days; though the soldiers stationed there before remained in the country and carried on the siege of Potidaea.

After the second invasion of the Peloponnesians a change came over the spirit of the Athenians. Their land had now been twice laid waste; and war and pestilence at once pressed heavy upon them.