History of the Peloponnesian War

Now all the time that the Peloponnesians were in the Athenian territory, and the Athenians were engaged in the expedition on board their ships, the plague was carrying them off both in the armament and in the city, so that it was even said that the Peloponnesians, for fear of the disorder, when they heard from the deserters that it was in the city, and also perceived them performing the funeral rites, retired the quicker from the country.

Yet in this invasion they stayed the longest time, and ravaged the whole country: for they were about forty days in the Athenian territory.

The same summer Hagnon son of Nicias, and Cleopompus son of Clinias, who were colleagues with Pericles, took the army which he had employed, and went straightway on an expedition against the Chalcidians Thrace-ward, and Potidaea, which was still being besieged: and on their arrival they brought up their engines against Potidaea, and endeavoured to take it by every means.

But they neither succeeded in capturing the city, nor in their other measures, to any extent worthy of their preparations: for the plague attacked them, and this indeed utterly overpowered them there, wasting their force to such a degree, that even the soldiers of the Athenians who were there before were infected with it by the troops which came with Hagnon, though previously they had been in good health. Phormio, however, and his sixteen hundred, were no longer in the neighbourhood of the Chalcidians [and so escaped its ravages].

Hagnon therefore returned with his ships to Athens, having lost by the plague fifteen hundred out of four thousand heavy-armed, in about forty days. The soldiers who were there before still remained in the country, and continued the siege of Potidaea.

After the second invasion of the Lacedaemonians, the Athenians, when their land had been again ravaged, and the disease and the war were afflicting them at the same time, changed their views, and found fault with Pericles, thinking that he had persuaded them to go to war, and that it was through him that they had met with their misfortunes;