According to Machiavelli, "When one wins, he ought to follow up the victory with all speed, and imitate Caesar in this case, and not Hannibal, who, because he had stopped after he had defeated the Romans at Cannae, lost the Empire of Rome. The other (Caesar) never rested after a victory, but pursued the routed enemy with great impetus and fury, until he had completely assaulted it."

"But when one loses, a Captain ought to see if something useful to him can result from this loss, especially if some residue of the army remains to him. An opportunity can arise from the unawareness of the enemy, which frequently becomes obscured after a victory, and gives you the occasion to attack him; as Martius, the Roman, attacked the Carthaginian army, which, having killed the two Scipios and defeated their armies, thought little of that remnant of the forces who, with Martius, remained alive; and was (in turn) attacked and routed by him. It is seen, therefore, that there is nothing so capable of success as that which the enemy believes you cannot attempt, because men are often injured more when they are less apprehensive."

from Niccolo Machiavelli, The Seven Books of the Art of War, Book 4 (1520)