History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
But they determined to take only half the ships across the isthmus first, and let these sail off immediately; that the Athenians might not attend to those which were setting out, so much as to those which were being conveyed across after them.