Res Gestae
Ammianus Marcellinus
Ammianus Marcellinus. Ammianus Marcellinus, with an English translation, Vols. I-III. Rolfe, John C., translator. Cambridge, MA; London: Harvard University Press; W. Heinemann, 1935-1940 (printing).
And since the heat had caused us parching thirst, for a long time we went slowly about looking for water. And we fortunately found a deep well,
From there we quickly made our way to the Euphrates river, planning to cross to the farther bank by a boat which long continued custom had kept in that vicinity for the transport of men and animals.
But lo! we saw afar off a scattered band of Romans with cavalry standards, pursued by a great force of Persians; and we could not understand how they appeared so suddenly behind us as we went along.