C. Julius Caesar, Gallic War

In the mean time, whilst these things are going on, the forces of the enemy from the Arverni, and the cavalry which had been demanded from all Gaul, meet together. A great number of these having been collected, when Caesar was marching into the country of the Sequani, through the confines of the Lingones , in order that he might the more easily render aid to the province, Vercingetorix encamped in three camps, about ten miles from the Romans: and having summoned the commanders of the cavalry to a council, he shows that the time of victory was come; that the Romans were fleeing into the Province and leaving Gaul; that this was sufficient for obtaining immediate freedom; but was of little moment in acquiring peace and tranquillity for the future; for the Romans would return after assembling greater forces and would not put an end to the war. Therefore they should attack them on their march, when encumbered. If the infantry should [be obliged to] relieve their cavalry, and be retarded by doing so, the march could not be accomplished: if, abandoning their baggage they should provide for their safety (a result which, he trusted, was more like to ensue), they would lose both property and character. For as to the enemy's horse, they ought not to entertain a doubt that none of them would dare to advance beyond the main body. In order that they [the Gauls] may do so with greater spirit, he would marshal all their forces before the camp, and intimidate the enemy. The cavalry unanimously shout out, "That they ought to bind themselves by a most sacred oath, that he should not be received under a roof, nor have access to his children, parents, or wife, who shall not twice have ridden through the enemy's army."