but no less so than the other alternative possibilities. Neither Polybius nor Livy gives any hint of why Hannibal involved himself in a local Gallic quarrel, and there is no obvious reason why he would have done so. All that is clear is the result: it was made clear to the Cisalpine Gauls that Hannibal had a formidable army, and some--presumably the Insubres, whom he had aided, but probably others as well--came over to his standard.
There was, however, no general uprising of the Gauls. Polybius hints that more would have come over to Hannibal had they not already been constrained by the presence of a Roman army: "The remaining Celtic inhabitants of the plain were impatient to join the Carthagenians, but as the Roman legions had advanced beyond most of them and cut them off, they kept quiet, some even being compelled to serve with the Romans." Livy makes the same point more colorfully; the Romans had "taken them by surprise, appearing unexpectedly whilst they were looking about them for a pretext to revolt. Livy also, however, suggest that the attitude of the Gauls was equivocal and opportunistic, ready to throw in the side that seemed more likely to win, or at least with the army that was most immediately at hand and so in a position to overawe them. "Hannibal ... moved forward from the Taurini, being persuaded that the Gauls, uncertain which side they had best adhere to, would attach themselves to those who were on the spot."
Later, in fact, Hannibal ravaged the territory of tribes allied to Rome as a goad to force the Roman army into an imprudent battle at Trebia. In any event, the uncertain attitude of the Gauls was a factor pushing both Hannibal and the Romans into an early battle. Each side could, by a quick victory (even if a non-decisive one) hope to solidify its own position in Cisalpine Gaul.
At about the same time as Hannibal's arrival in Italy, the Roman army in this northern theater passed unde...