History of the Peloponnesian War

When the business was still undecided, the commander of the Messenians came to Cleon and Demosthenes, and told them that they were labouring in vain; but if they would give him a part of the bowmen and light-armed, to go round in their rear by a way that he should himself discover, he thought he could force the approach.

Having received what he asked for, he started from a point out of the enemy's sight, that they might not observe it, and, advancing wherever the precipitous side of the island allowed a passage, and where the Lacedaemonians, relying on the strength of the ground, kept no guard, with great labour and difficulty he got round unobserved, and suddenly appearing on the height in their rear, struck the enemy with dismay at the unexpected movement, and gave much greater confidence to his friends by the sight of what they were looking for.

And now the Lacedaemonians were exposed to missiles on both sides, and reduced to the same result (to compare a small case with a great one) as that which happened at Thermopylae; for those troops were cut off through the Persians' getting round by the path; and these, being more assailed on all sides, no longer held their ground, but from fighting, as they were, a few against many, and from weakness of body through want of provisions, they began to retreat; and so the Athenians now commanded the approaches.