History of the Peloponnesian War

And having received the forces he asked, he took his way from a place out of sight to the Lacedaemonians that he might not be discovered making his approach under the cliffs of the island where they were continual in which part, trusting to the natural strength thereof, they kept no watch, and with much labour and hardly unseen, came behind them, and appearing suddenly from above at their backs, both terrified the enemies with the sight of what they expected not and much confirmed the Athenians with the sight of what they expected.

And the Lacedaemonians, being now charged with their shot both before and behind, were in the same case (to compare small matters with great) that they were in at Thermopylae. For then they were slain by the Persians, shut up on both sides in a narrow path; and these now, being charged on both sides, could make good the place no longer, but fighting few against many and being weak withal for want of food, were at last forced to give ground; and the Athenians by this time were also masters of all the entrances.