Appian of Alexandria Civil Wars 2.11.80

[80] As Pompey’s left wing began to give way his men even still retired step by step and in perfect order, but the allies who had not been in the fight, fled with headlong speed, shouting, we are vanquished, dashed upon their own tents and fortifications as though they had been the enemy’s, and pulled down and plundered whatever they could carry away in their flight. Now the rest of Pompey’s legions, perceiving the disaster to the left wing, retired slowly at first, in good order, and still resisting as well as they could; but when the enemy, flushed with victory, pressed upon them they turned in flight. Then, in order that they might not rally, and that this might be the end of the whole war and not of one battle merely, Caesar, with the greatest prudence, sent heralds everywhere among the ranks to order the victors to spare their own countrymen and to smite only the auxiliaries. The heralds drew near to the retreating enemy and told them to stand still without fear. As this proclamation was passed from man to man they halted, and the phrase stand without fear began to be passed as a sort of watchword among Pompey’s soldiers; for, being Italians, they were clad in the same style as Caesar’s men and spoke the same language. Accordingly, the latter passed by them and fell upon the auxiliaries, who were not able to resist, and made a very great slaughter among them. ¹