Anabasis (1.8.15-1.8.19)

Then Xenophon,[*] an Athenian, seeing him from the Greek army, approached so as to meet him and asked if he had any orders to give; and Cyrus pulled up his horse and bade Xenophon tell everybody that the sacrificial victims and omens were all favourable.

While saying this he heard a noise running through the ranks, and asked what the noise was. Xenophon replied that the watchword was now passing along for the second time.[*] And Cyrus wondered who had given it out, and asked what the watchword was. Xenophon replied

And upon hearing this Cyrus said,

And when, as they proceeded, a part of the phalanx billowed out, those who were thus left behind began to run; at the same moment they all set up the sort of war-cry which they raise to Enyalius,[*] and all alike began running. It is also reported that some of them clashed their shields against their spears, thereby frightening the enemy’s horses.

And before an arrow reached them, the barbarians broke and fled. Thereupon the Greeks pursued with all their might, but shouted meanwhile to one another not to run at a headlong pace, but to keep their ranks in the pursuit.