History of the Peloponnesian War

For he wished by their great dimensions and thickness to keep off the attacks of their enemies; and thought that the protection of a few, and those the least efficient troops, would be sufficient, while the rest would go on board their ships.

For to the navy he paid the greatest attention; seeing, I suppose, that the approach of the king's forces against them was easier by sea than by land: and he considered the Piraeus more serviceable than the upper city, and often advised the Athenians, in case of their ever being hard pressed by land, to go down into it, and defy the world with their navy.