History of the Peloponnesian War
Thucydides
Thucydides. History of the Peloponnesian War. Crawley, Richard, translator. London and Toronto: J. M. Dent and Sons Ltd.; New York: E. P. Dutton and Co., 1914.
The moment they gave way, the light troops became bolder and pressed upon them, shouting louder than ever, and killed as many as they came up with in their retreat, but most of the Lacedaemonian made good their escape to the fort, and with the garrison in it ranged themselves all along its whole extent to repulse the enemy wherever it was assailable.
The Athenians pursuing, unable to surround and hem them in, owing to the strength of the ground, attacked them in front and tried to storm the position.
For a long time, indeed for most of the day, both sides held out against all the torments of the battle, thirst, and sun, the one endeavoring to drive the enemy from the high ground, the other to maintain himself upon it, it being now more easy for the Lacedaemonians to defend themselves than before, as they could not be surrounded upon the flanks.