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.
While they were resting, Gylippus and the Syracusans sent a part of their troops to intercept them again with a wall on their rear, where they had already passed: but they, on their side also, sent some of their men against them, and prevented their doing it.
After this, the Athenians returned again with all their army into the more level country, and there halted for the night. The next day they marched forward, while the Syracusans discharged their weapons on them, surrounding them on all sides, and disabled many with wounds; retreating if the Athenians advanced against them, and pressing on them if they gave way; most especially attacking their extreme rear, in the hope that by routing them little by little, they might strike terror into the whole army.