Xenophon Hellenica 7.5.24

[24] Epaminondas on the other hand had made a strong column of his cavalry, also, and had mingled foot soldiers among them, believing that when he cut through the enemy’s cavalry, he would have defeated the entire opposing army; for it is very hard to find men who will stand firm when they see any of their own side in flight. And in order to prevent the Athenians on the left wing from coming to the ¹ aid of those who were posted next to them, he stationed both horsemen and hoplites upon some hills over against them, desiring to create in them the fear that if they proceeded to give aid, these troops would fall upon them from behind.
  Thus, then, he made his attack, and he was not disappointed of his hope; for by gaining the mastery at the point where he struck, he caused the entire army of his adversaries to flee.