C. Julius Caesar, Gallic War

That matter being determined on, marching out of their camp at the second watch, with great noise and confusion, in no fixed order, nor under any command, since each sought for himself the foremost place in the journey, and hastened to reach home, they made their departure appear very like a flight. Caesar, immediately learning this through his scouts, [but] fearing an ambuscade, because he had not yet discovered for what reason they were departing, kept his army and cavalry within the camp. At daybreak, the intelligence having been confirmed by the scouts, he sent forward his cavalry to harass their rear; and gave the command of it to two of his lieutenants, Q. Pedius, and L. Aurunculeius Cotta. He ordered T. Labienus, another of his lieutenants, to follow them closely with three legions. These, attacking their rear, and pursuing them for many miles, slew a great number of them as they were fleeing; while those in the rear with whom they had come up, halted, and bravely sustained the attack of our soldiers; the van, because they appeared to be removed from danger, and were not restrained by any necessity or command, as soon as the noise was heard, broke their ranks, and, to a man, rested their safety in flight. Thus without any risk [to themselves] our men killed as great a number of them as the length of the day allowed; and at sunset desisted from the pursuit, and betook themselves into the camp, as they had been commanded.