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.

But before they had left the plain and entered the Paralus, Pericles had begun to equip a fleet of a hundred ships to sail against the Peloponnesus, and when all was ready he put to sea.

He took with him on the ships four thousand Athenian hoplites and three hundred cavalry in horse-transports, then employed for the first time, which had been made out of the old galleys.