Hannibal was perfectly aware of the difficulties of his position. Had he been free and unencumbered by baggage he might have led his army directly across the wooded mountains, avoiding the passes guarded by the Romans, but with his enormous trail of baggage this was impossible unless he abandoned all the rich plunder which the army had collected. Of the two outlets from the plain, by the Appian and Latin roads which led to Rome, neither could be safely attempted, for the Roman army would have followed in his rear, and attacked him while endeavouring to force the passages in the mountains.
The same objection applied to his crossing the Vulturnus. The only bridge was strongly held by the Romans, and the river was far too deep and rapid for a passage to be attempted elsewhere with the great Roman army close at hand. The mountain range between the Vulturnus and Cades was difficult in the extreme, as the passes were few and very strongly guarded, but it was here that Hannibal resolved to make the attempt to lead his army from the difficult position in which it was placed. He waited quietly in the plain until the supplies of food were beginning to run low, and then prepared for his enterprise.
An immense number of cattle were among the plunder. Two thousand of the stoutest of these were selected, torches were fastened to their horns, and shortly before midnight the light troops drove the oxen to the hills, avoiding the position of the passes guarded by the enemy. The torches were then lighted, and the light troops drove the oxen straight up the hill. The animals, maddened by fear, rushed tumultuously forward, scattering in all directions on the hillside, but, continually urged by the troops behind them, mounting towards the summits of the hills.
The Roman defenders of the passes, seeing this great number of lights moving upwards, supposed that Hannibal had abandoned all his baggage, and was leading his army straight across the hills. This idea was confirmed by the light troops, on gaining the crest of the hills, commencing an attack upon the Romans posted below them in the pass through which Hannibal intended to move. The Roman troops thereupon quitted the pass, and scaled the heights to interrupt or harass the retreating foe.
As soon as Hannibal saw the lights moving on the top of the hills he commenced his march. The African infantry led the way; they were followed by the cavalry; then came the baggage and booty, and the rear was covered by the Spaniards and Gauls. The defile was found deserted by its defenders, and the army marched through unopposed. Meanwhile Fabius with his main army had remained inactive. The Roman general had seen with astonishment the numerous lights making their way up the mountain side, but he feared that this was some device on the part of Hannibal to entrap him into an ambush, as he had entrapped Flaminius on Lake Trasimene. He therefore held his army in readiness for whatever might occur until morning broke.