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.
After the armistice had expired Cleon persuaded the Athenians to let him sail to the cities in Thrace, with twelve hundred Athenian hoplites and three hundred cavalry, and a larger force of the allies, and thirty ships.