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.