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.
for in the ditch ice had formed that was not firm enough to walk on but mushy, such as is formed when the wind is east instead of north; and since the night, the wind being from that quarter, was somewhat snowy, the water in the ditch had become so deep that they could scarcely keep their heads above it as they crossed. It was, however, chiefly the violence of the storm that enabled them to escape at all.
Starting from the ditch, the Plataeans advanced in a body along the road toward Thebes, having on their right the shrine of the hero Androcrates; for they thought that no one would ever suspect them of having taken this road, which led towards their enemies; besides, they saw the Peloponnesians, torches in hand, taking in pursuit the road toward Cithaeron and Dryoscephalae, which is the road to Athens.