Scipio, who, with an army considerably smaller and very weak in cavalry, had the difficult task of preventing the advance of the superior force of the enemy and of repressing the movements of insurrection which everywhere were spreading among the Celts, had crossed the Po presumably at Placentia, and marched up the river to meet the enemy, while Hannibal after the capture of Turin marched downwards to relieve the Insubres and Boii. In the plain between the Ticino and the Sesia, not far from Vercelli, the Roman cavalry, which had advanced with the light infantry to make a reconnaissance in force, encountered the Punic cavalry sent out for the like purpose, both led by the generals in person. Scipio accepted battle when offered, notwithstanding the superiority of the enemy; but his light infantry, which was placed in front of the cavalry, dispersed before the charge of the heavy cavalry of the enemy, and while the latter engaged the masses of the Roman horsemen in front, the light Numidian cavalry, after having pushed aside the broken ranks of the enemy's infantry, took the Roman horsemen in flank and rear. This decided the combat. The loss of the Romans was very considerable. The consul himself, who made up as a soldier for his deficiencies as a general, received a dangerous wound, and owed his safety entirely to the devotion of his son of seventeen, who, courageously dashing into the ranks of the enemy, compelled his squadron to follow him and rescued his father. Scipio, enlightened by this combat as to the strength of the enemy, saw the error which he had committed in posting himself, with a weaker army, in the plain with his back to the river, and resolved to return to the right bank of the Po under the eyes of his antagonist. As the operations became contracted into a narrower space and his illusions regarding Roman invincibility departed, he recovered the use of his considerable military talents, which the adventurous boldness of his youthful opponent's plans had for a moment paralyzed. While Hannibal was preparing for a pitched battle, Scipio by a rapidly projected and steadily executed march succeeded in reaching the right bank of the river which in an evil hour he had abandoned, and broke down the bridge over the Po behind his army; the Roman detachment of 600 men charged to cover the process of destruction were, however, intercepted and made prisoners. But as the upper course of the river was in the hands of Hannibal, he could not be prevented from marching up the stream, crossing on a bridge of boats, and in a few days confronting the Roman army on the right bank. The latter had taken a position in the plain in front of Placentia; but the mutiny of a Celtic division in the Roman camp, and the Gallic insurrection breaking out afresh all around, compelled the consul to evacuate the plain and to post himself on the hills behind the Trebia. This was accomplished without notable loss, because the Numidian horsemen sent