VI. When Flaminius and his colleague had resigned their offices, Marcellus was designated consul by the interreges.[14] On entering upon his office he nominated Cnaeus Cornelius as his colleague. It was said that the Gauls were offering terms of reconciliation, and that the Senate wished for peace with them, but that Marcellus raised the spirit of the people and excited them to continue the war. But still a peace was concluded; and it seems to have been the Gaesatae who renewed the war, by crossing the Alps and stirring up the Insubrians. Thirty thousand in number, they joined that tribe, which was many times larger, and in high spirits at once attacked Acerrae, a city beyond the river Po. From that place Britomartus with ten thousand Gaesatae proceeded to plunder the country near the Po.
Marcellus hearing this left his colleague before Acerrae with the infantry, heavy baggage, and one-third of the cavalry, and himself, with the rest of the cavalry and about six hundred of the most active foot soldiers, marched night and day till he fell in with the ten thousand Gaesatae at Clastidium, a Gaulish village which not long before had been subject to the Romans. There was no time for rest or refreshment; for his arrival was at once perceived by the enemy, and his force despised, as he had so little infantry with him, for the Celts thought nothing of his cavalry. Admirable horsemen and proud of their superior skill, they also had greatly the advantage of Marcellus in numbers, and at once, their king riding foremost, charged the Romans with great impetuosity and terrible threats, expecting to sweep them away. Marcellus, fearing that they might surround and outflank his small body, spread out his cavalry, thinning and widening his line, until he presented a front nearly equal to that of the enemy. He was now advancing to the charge, when his horse, scared at the terrible display of the enemy, turned short round, and forcibly carried him back. Marcellus, fearing that this might cause superstitious terror to the Romans, hastily wheeled his horse round on the bridle hand, and having again directed him against the enemy, paid his adorations to the sun, as though he had made this circle not by chance, but of set purpose; for the Romans have this custom, of turning round to worship the gods, and so he, as he was on the point of joining battle, vowed that he would consecrate the finest of the enemies’ arms to Jupiter Feretrius.