Titus Livius (Livy), The History of Rome, Book 21
Benjamin Oliver Foster, Ph.D., Ed.

29. Whilst the elephants were being got across, Hannibal had dispatched five hundred Numidian horsemen in the direction of the Roman camp, to find out where the enemy were and in what force, and what they meant to do. [2] This body fell in with the three hundred Roman horsemen, sent out, as was mentioned before, from the mouth of the Rhone. [3] The battle that followed was more hotly fought than the size of the contending forces would suggest, for besides the many who were [p. 85]wounded, the numbers of the slain were about equal¹ on both sides, and only the dismay and panic of the Numidians gave the victory to the Romans, who were by that time fairly exhausted. The victors lost about a hundred and forty, not all Romans but some of them Gauls; the vanquished about two hundred. [4] This was at once the beginning of the war and an omen that promised the Romans success in the final outcome, though their victory would be by no means without bloodshed and would only come after a doubtful struggle.

[5] When the participants in this affair had returned to their respective generals, it was impossible for Scipio to adopt any settled plan, except to frame his own measures to meet the strategy and movements of the enemy; [6] while Hannibal, uncertain whether to march on, as he had begun, to Italy, or give battle to the first Roman army that had come in his way, was diverted from an immediate trial of strength by the arrival of Boian envoys, with their chief Magalus. These assured him that they would guide his march and share its perils, and urged him to avoid a battle and to keep his forces whole and unimpaired for the invasion of Italy. [7] The rank and file were fearful of the enemy —for their memory of the former war was not yet erased —but more fearful of the interminable march over the Alps, an undertaking which rumour made appalling, at any rate to the inexperienced.