C. Julius Caesar, Gallic War

After having established this suspicion of his cowardice, he selected a certain suitable and crafty Gaul, who was one of those whom he had with him as auxiliaries. He induces him by great gifts and promises to go over to the enemy; and informs [him] of what he wished to be done. Who, when he arrives among them as a deserter, lays before them the fears of the Romans; and informs them by what difficulties Caesar himself was harassed, and that the matter was not far removed from this- that Sabinus would the next night privately draw off his army out of the camp and set forth to Caesar for the purpose of carrying [him] assistance, which, when they heard, they a11 cry out together that an opportunity of successfully conducting their enterprise, ought not to be thrown away: that they ought to go to the [Roman] camp. Many things persuaded the Gauls to this measure; the delay of Sabinus during the previous days; the positive assertion of the [pretended] deserter; want of provisions, for a supply of which they had not taken the requisite precautions; the hope springing from the Venetic war; and [also] because in most cases men willingly believe what they wish. Influenced by these things they do not discharge Viridovix and the other leaders from the council, before they gained permission from them to take up arms and hasten to [our] camp; which being granted, rejoicing as if victory were fully certain, they collected faggots and brushwood, with which to fill up the Roman trenches, and hasten to the camp.