Thus Rome would be defended by forty-three thousand men, while Hannibal had but thirty-three thousand infantry, and his cavalry, the strongest arm of his force, would be useless. From Cannae to Rome was twelve days' march with an army encumbered with booty. He could not, therefore, hope for a surprise. The walls of Rome were exceedingly strong, and he had with him none of the great machines which would have been necessary for a siege. He must have carried with him the supplies he had accumulated for the subsistence of his force, and when these were consumed he would be destitute. Fresh Roman levies would gather on his rear, and before long his whole army would be besieged.

In such an undertaking he would have wasted time, and lost the prestige which he had acquired by his astonishing victory. Varro, who had escaped from the battle, had rallied ten thousand of the fugitives at the strong place of Canusium, and these would be a nucleus round which the rest of those who had escaped would rally, and would be joined by fresh levies of the Italian allies of Rome.