Hmm...If I look at this from pure army makeup we are outnumbered and outgunned, but can make this fight hell. Victrix has the siege equipment/Heavy ranged weapons to combat the elephants, and the Celeris Acuta would volunteer to skirmish with Hannibal to buy the main defense what little extra time it can with guerilla tactics (And then join the defenses), but what it comes down to is us being outnumbered and overrun-- or, at the least, failing to halt them at the river. We might be able to hold it for a short time, but their superior numbers just...are superior!

That said, they've (roughly, by no means did I clarify my math) 45-50,000 troops to our combined ~17-20,000. I vote we aim to make it hell and retreat.