At length, certainly, the greater part of the army and of the fleet was got ready for the expedition to Africa, and the second consul Publius Cornelius Scipio was ordered to the Ebro; but he took time, and when an insurrection broke out on the Po, he allowed the army that was ready for embarkation to be employed there, and formed new legions for the Spanish expedition. So although Hannibal encountered on the Ebro very vehement resistance, it proceeded only from the natives; and, as under existing circumstances time was still more precious to him than the blood of his men, he surmounted the opposition after some months with the loss of a fourth part of his army, and reached the line of the Pyrenees. That the Spanish allies of Rome would be sacrificed a second time by that delay might have been as certainly foreseen, as the delay itself might have been easily avoided; but probably even the expedition to Italy itself, which in the spring of 536 must not have been anticipated in Rome, would have been averted by the timely appearance of the Romans in Spain. Hannibal had by no means the intention of sacrificing his Spanish "kingdom", and throwing himself like a desperado on Italy. The time which he had spent in the siege of Saguntum and in the reduction of Catalonia, and the considerable corps which he left behind for the occupation of the newly-won territory between the Ebro and the Pyrenees, sufficiently show that, had a Roman army disputed the possession of Spain with him, he would not have been content to withdraw from it; and - which was the main point - had the Romans been able to delay his departure from Spain for but a few weeks, winter would have closed the passes of the Alps before Hannibal reached them, and the African expedition would have departed without hindrance for its destination.
Arrived at the Pyrenees, Hannibal sent home a portion of his troops; a measure which he had resolved on from the first with the view of showing to the soldiers how confident their general was of success, and of checking the feeling that his enterprise was one of those from which there is no return home. With an army of 50,000 infantry and 9000 cavalry, entirely veteran soldiers, he crossed the Pyrenees without difficulty, and then took the coast route by Narbonne and Nimes through the Celtic territory, which was opened to the army partly by the connections previously formed, partly by Carthaginian gold, partly by arms. It was not till it arrived in the end of July at the Rhone opposite Avignon, that a serious resistance appeared to await it. The consul Scipio, who on his voyage to Spain had landed at Massilia (about the end of June), had there been informed that he had come too late and that Hannibal had crossed not only the Ebro but the Pyrenees. On receiving these accounts, which appear to have first opened the eyes of the Romans to the course and the object of Hannibal, the consul had temporarily given up his expedition to Spain, and had resolved in connection with the Celtic tribes of that region, who were under the influence of the Massiliots and thereby under that of Rome, to receive the Phoenicians on the Rhone, and to obstruct their passage of the river and their march into Italy. Fortunately for Hannibal, opposite to the point at which he meant to cross, there lay at the moment only the general levy of the Celts, while the consul himself with his army of 22,000 infantry and 2000 horse was still in Massilia, four days' march farther down the stream. The messengers of the Gallic levy hastened to inform him. It was the object of Hannibal to convey his army with its numerous cavalry and elephants across the rapid stream under the eyes of the enemy, and before the arrival of Scipio; and he possessed not a single boat. Immediately by his directions all the boats belonging to the numerous navigators of the Rhone in the neighbourhood were bought up at any price, and the deficiency of boats was supplied by rafts made from felled trees; and in fact the whole numerous army could be conveyed over in one day. While this was being done, a strong division under Hanno, son of Bomilcar, proceeded by forced marches up the stream till they reached a suitable point for crossing, which they found undefended, situated two short days' march above Avignon. Here they crossed the river on hastily constructed rafts, with the view of then moving down on the left bank and taking the Gauls, who were barring the passage of the main army, in the rear. On the morning of the fifth day after they had reached the Rhone, and of the third after Hanno's departure, the smoke-signals of the division that had been detached rose up on the opposite bank and gave to Hannibal the anxiously awaited summons for the crossing. Just as the Gauls, seeing that the enemy's fleet of boats began to move, were hastening to occupy the bank, their camp behind them suddenly burst into flames. Surprised and divided, they were unable either to withstand the attack or to resist the passage, and they dispersed in hasty flight.
Scipio meanwhile held councils of war in Massilia as to the proper mode of occupying the ferries of the Rhone, and was not induced to move even by the urgent messages that came from the leaders of the Celts. He distrusted their accounts, and he contented himself with detaching a weak Roman cavalry division to reconnoitre on the left bank of the Rhone. This detachment found the whole enemy's army already transported to that bank, and occupied in bringing over the elephants which alone remained on the right bank of the stream; and, after it had warmly engaged some Carthaginian squadrons in the district of Avignon, merely for the purpose of enabling it to complete its reconnaissance - the first encounter of the Romans and Phoenicians in this war - it hastily returned to report at head-quarters. Scipio now started in the utmost haste with all his troops for Avignon; but, when he arrived there, even the Carthaginian cavalry that had been left behind to cover the passage of the elephants had already taken its departure three days ago, and nothing remained for the consul but to return with weary troops and little credit to Massilia, and to revile the "cowardly flight" of the Punic leader. Thus the Romans had for the third time through pure negligence abandoned their allies and an important line of defence; and not only so, but by passing after this first blunder from mistaken slackness to mistaken haste, and by still attempting without any prospect of success to do what might have been done with so much certainty a few days before, they let the real means of repairing their error pass out of their hands. When once Hannibal was in the Celtic territory on the Roman side of the Rhone, he could no longer be prevented from reaching the Alps; but if Scipio had at the first accounts proceeded with his whole army to Italy - the Po might have been reached by way of Genoa in seven days - and had united with his corps the weak divisions in the valley of the Po, he might have at least prepared a formidable reception for the enemy. But not only did he lose precious time in the march to Avignon, but, capable as otherwise he was, he wanted either the political courage or the military sagacity to change the destination of his corps as the change of circumstances required. He sent the main body under his brother Gnaeus to Spain, and returned himself with a few men to Pisae.