History of the Peloponnesian War

The Corinthians, having heard long before from Argos that the armament of the Athenians was coming, went with succours to the Isthmus, all but those who lived above it: there were absent too in Ambracia and Leucadia five hundred of them, serving as a garrison; but the rest, with all their forces, were watching where the Athenians would make the land.

But when they had come to during the night unobserved by them, and the appointed signals were raised to tell them of the fact, they left half their forces at Cenchreae, in case the Athenians should advance against Crommyon, and went to the rescue with all speed.