The two armies when facing each other in order of battle must have presented a curious contrast. The Roman legions and their allies, amounting in all to seventy-six thousand men, wore helmets and cuirasses and carried swords and short throwing-spears. In front, the Carthaginian troops looked a mere motley crowd, so various were the dress and weapons of the different nations. It is true that the black-skinned Libyans might at first sight have been taken for deserters from the Roman camp, as they, like their enemies, were clad in the same armour and bore the same arms, the spoils of many a victory; and the young men of the legions trembled with rage as they beheld the glittering line, and thought of what it betokened. But the Gauls were almost naked, and their swords, unlike those of the Romans, could only cut, and were useless for thrusting, while the Spanish troops were clothed in a uniform of short linen tunics striped with purple. In the van, or front of the army, were the small remainder of the contingent from the Balearic Isles, with their slings and bows.
In spite of the faults committed by Varro in placing his troops, Hannibal's lines were once broken by the heavy-armed Roman soldiers, while the cavalry on the wing by the river were fighting in such deadly earnest that they leaped from their horses and closed man to man. But at Cannæ, as at Trebia, the honours of the day fell to the Numidians and to the Spanish and Gallic horse commanded by Hasdrubal. The Romans had been again routed by an army weaker by thirty thousand men than their own; the consul Paulus, and Servilius and Atilius, consuls of the year before, were all dead: only Varro saved his life by a disgraceful flight.
Still Hannibal did not march to Rome, as the senate expected. Though the battle of Cannæ decided the wavering minds of those who had been waiting to see on which side lay the victory; though the southern half of Italy and many cities of Campania were now anxious to throw in their lot with him; though Philip of Macedon promised once more to send ships and men to his support, and thousands of Gauls swarmed into his camp, the army on which he could actually rely was too small to besiege the city with any chance of success. He did, indeed, send ambassadors to Rome, with powers to treat for the ransoming of some Roman prisoners, but as before in the case of the Gauls, the envoys were not even given a hearing by the senate.
Till he got reinforcements from Carthage, Hannibal felt he must remain where he was; but surely she would delay no longer when she knew that the moment for which Hannibal was waiting had come, and his allies were ready. So he sent his brother Mago to tell the story of his triumphs and his needs to the Carthaginian senate, never doubting that a few weeks would see the tall-prowed ships sailing up the coast of the Tyrrhene sea, where he now had his headquarters. He did not reckon on the jealousy of his success which filled the breasts of the rulers of his country, a jealousy which even self-interest was unable to overcome. From the first he had borne their burden alone, and owing to the treachery and baseness of his own nation in the end it proved too heavy for his shoulders.
Soon Hannibal began to understand that he would get help from no one, and from Carthage least of all, and the knowledge was very bitter. The Romans had gathered together a fresh army of eighty or ninety thousand men, and had armed a large number of their slaves, offering them freedom. Any check, however slight, to the Carthaginian army was the cause of joy and thankfulness in Rome, for, as Livy says, 'not to be conquered by Hannibal then was more difficult than to vanquish him afterwards.'
In spite of Thrasymene and Cannæ things were now changed, and it was Hannibal who was on the defensive. The Romans had learned their lesson, and the legions always lying at the heels of Hannibal's army were commanded by experienced generals, who adopted the policy of Fabius and were careful never to risk a battle.
Thus three years passed away, and Carthage, absorbed in the difficult task of keeping Spain, from which she drew so much of her wealth, in her hands, sent thither all the troops she could muster to meet the Romans, who were gradually gaining ground in the peninsula.