In this way, while the two great Roman armies, each in itself equal in numbers to that of Hannibal, remained at a great distance from the valley of the Po, the Romans were quite unprepared for an attack in that quarter. No doubt a Roman army was there, in consequence of an insurrection that had broken out among the Celts even before the arrival of the Carthaginian army. The founding of the two Roman strongholds of Placentia and Cremona, each of which received 6000 colonists, and more especially the preparations for the founding of Mutina in the territory of the Boii, had already in the spring of 536 driven the Boii to revolt before the time concerted with Hannibal; and the Insubres had immediately joined them. The colonists already settled in the territory of Mutina, suddenly attacked, took refuge in the town. The praetor Lucius Manlius, who held the chief command at Ariminum, hastened with his single legion to relieve the blockaded colonists; but he was surprised in the woods, and no course was left to him after sustaining great loss but to establish himself upon a hill and to submit to a siege there on the part of the Boii, till a second legion sent from Rome under the praetor Lucius Atilius succeeded in relieving army and town, and in suppressing for the moment the Gaulish insurrection. This premature rising of the Boii on the one hand, by delaying the departure of Scipio for Spain, essentially promoted the plans of Hannibal; on the other hand, but for its occurrence he would have found the valley of the Po entirely unoccupied, except the fortresses. But the Roman corps, whose two severely thinned legions did not number 20,000 soldiers, had enough to do to keep the Celts in check, and did not think of occupying the passes of the Alps. The Romans only learned that the passes were threatened, when in August the consul Publius Scipio returned without his army from Massilia to Italy, and perhaps even then they gave little heed to the matter, because, forsooth, the foolhardy attempt would be frustrated by the Alps alone. Thus at the decisive hour and on the decisive spot there was not even a Roman outpost. Hannibal had full time to rest his army, to capture after a three days’ siege the capital of the Taurini which closed its gates against him, and to induce or terrify into alliance with him all the Ligurian and Celtic communities in the upper basin of the Po, before Scipio, who had taken the command in the Po valley, encountered him.