History of the Peloponnesian War

And thus they held out a long time, the better part of a day, either side tired with the fight and with thirst and with the sun, one endeavouring to drive the enemy from the top, the other to keep their ground. And the Lacedaemonians defended themselves easilier now than before because they were not now encompassed upon their flanks.

When there was no end of the business, the captain of the Messenians said unto Cleon and Demosthenes that they spent their labour there in vain and that if they would deliver unto him a part of the archers and light-armed soldiers to get up by such a way as he himself should find out and come behind upon their backs, he thought the entrance might be forced.

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.