Niccolò Machiavelli
Discourses on the First Decade of Titus Livius (Chap. 3.40)
That Fraud is fair in War.

Although in all other affairs it be hateful to use fraud, in the operations of war it is praiseworthy and glorious; so that he who gets the better of his enemy by fraud, is as much extolled as he who prevails by force. This appears in the judgments passed by such as have written of the lives of great warriors, who praise Hannibal and those other captains who have been most noted for acting in this way. But since we may read of many instances of such frauds, I shall not cite them here. This, however, I desire to say, that I would not have it understood that any fraud is glorious which leads you to break your plighted word, or to depart from covenants to which you have agreed; for though to do so may sometimes gain you territory and power, it can never, as I have said elsewhere, gain you glory.

The fraud, then, which I here speak of is that employed against an enemy who places no trust in you, and is wholly directed to military operations, such as the stratagem of Hannibal at the Lake of Thrasymene, when he feigned flight in order to draw the Roman consul and his army into an ambuscade; or when to escape from the hands of Fabius Maximus he fastened lights to the horns of his oxen. Similar to the above was the deceit practised by Pontius the Samnite commander to inveigle the Roman army into the Caudine Forks. For after he had drawn up his forces behind the hills, he sent out a number of his soldiers, disguised as herdsmen, to drive great herds of cattle across the plain; who being captured by the Romans, and interrogated as to where the Samnite army was, all of them, as they had been taught by Pontius, agreed in saying that it had gone to besiege Nocera: which being believed by the consuls, led them to advance within the Caudine Valley, where no sooner were they come than they were beset by the Samnites. And the victory thus won by a fraud would have been most glorious for Pontius had he but taken the advice of his father Herennius, who urged that the Romans should either be set at liberty unconditionally, or all be put to death; but that a mean course "which neither gains friends nor gets rid of foes" should be avoided. And this was sound advice, for, as has already been shown, in affairs of moment a mean course is always hurtful.