When war was declared between Rome and Carthage, Rome’s superiority at sea led her to suppose that she could choose the theatre for the new conflict. And she chose Spain and Africa. One consul, P. Cornelius Scipio, with some 24,000 men and 60 ships, was to conduct the war in Spain, while Ti. Sempronius Longus with about 26,000 troops and 160 vessels was sent to Sicily preparatory to crossing to Africa. The size of the African expeditionary force shows that Rome had no intention of striking immediately at Carthage itself. A demonstration could be made, the native tribes won over, the large estates of the nobles ravaged, and reinforcements for Hannibal intercepted; further support could be sent if events in Europe justified it. Meantime Hannibal must be watched. Naval inferiority would force him to seek the enemy by land either on the defensive in Spain or by an offensive in northern Italy. And because of the fiery spirit of the Barcid house and Hannibal’s intrigues with the Gauls, the Romans might expect him to take the offensive, cross the Ebro, and advance gradually, consolidating his communications en route. So they decided to send an army to check him either in northern Spain or more probably in southern Gaul, since an immediate Roman offensive in Spain with no base and in face of the enemy’s superior numbers would be hazardous. Resistance would be easier near the friendly Massilia and in reach of their base at Pisa, while Hannibal’s strength would be less when he arrived there; after repulsing him at the Rhône, the Romans could launch an offensive in northern Spain. But whether they hoped to meet him in Spain or Gaul, they underestimated one factor – his genius.
Hannibal was not content to meet the enemy in Spain and Africa. He realized that a Roman victory in Africa would mean the loss of the war and that therefore he must strike first, while Carthaginian victories in Africa would not break the power of Rome, which could only be smashed beyond recovery by destroying her Italian confederacy. He determined therefore to cut off her source of strength by fighting in Italy and disintegrating the League. His chances of reaching Italy must have seemed meagre, as Rome guarded the seas and the land route was long and difficult, but he trusted in his ability to overcome the obstacles. Where he miscalculated was by assuming that Rome’s allies were unwilling slaves of a tyrannical mistress. He hoped that they would rise to acclaim him as liberator, while Pyrrhus’ career had shown that an army in Italy could seriously embarrass Rome. Further, he could count on the Gauls in northern Italy rallying to his banner; these traditional enemies of Rome, though recently defeated, were not completely crushed. So he formed the bold scheme of sacrificing his communications with Spain and Carthage and swooping suddenly on to northern Italy, which would form a base in place of Spain. He started with a veteran army of perhaps 35,000 or 40,000 men; for the defence of Africa there were some 20,000 men, while he left 15,000 in southern Spain and another 11,000 north of the Ebro.1 The total forces which Carthage put into the field were about 80,000 soldiers, 100 ships and 25,000 marines; Rome mustered 70,000 men, 220 ships and 50,000–60,000 sailors. The seriousness of the struggle is shown by the numbers raised by the two Republics, although each of them could have doubled these if necessary. But Rome had two decisive factors in her favour: superiority at sea and the superior quality of the reserve troops which she could produce in her hour of need. The best troops of Carthage were already in the field.
At the end of April 218, Hannibal started on his crusade from New Carthage; he crossed the Ebro in early June when the spring flooding of the river had subsided, but he did not reach the Rhône till mid-August. This delay was hardly caused by a serious attempt to subdue the intervening tribes, because he had determined to sacrifice his communications. Possibly he encountered stronger opposition than he had anticipated, or perhaps he marched slowly to deceive the Romans, thinking that if he passed the Pyrenees by the end of July he could then dash forward and get through the Alpine passes before they closed in the autumn. In this way he would lull the enemy’s suspicions and avoid the risk that the four consular legions might concentrate in northern Italy. At the Rhône he would have found P. Scipio waiting to contest his passage, had not the Roman plans miscarried. The Boii and Insubres around the new Latin colonies of Placentia and Cremona (p. 172) rebelled, doubtless at Hannibal’s instigation, and the two legions which Scipio had prepared for Spain had to be directed to suppress the insurrection. However, Scipio raised two new legions and reached the mouth of the Rhône by the middle of August. Little realizing Hannibal’s real intentions he sent out a cavalry detachment to reconnoitre. Meantime Hannibal, who had found his crossing of the Rhône challenged by hostile tribes on the further bank, sent a force under Hanno across the river higher up, and when they were ready to fall on the rear of the Gauls, he crossed over and won a victory. Scipio’s reconnoitring force, after severely handling a Numidian scouting squadron, returned to headquarters to inform him that Hannibal had crossed the Rhône. Three days later Scipio arrived on the spot and found Hannibal’s camp deserted and that he had crossed the river, elephants and all,2 and was marching to the Alps. He then took a momentous decision. Instead of attempting a wild goose chase after Hannibal, he sent his army under his brother Gnaeus to Spain, where the enemy might be held at bay now that Hannibal’s best troops had gone. Scipio himself returned by sea to northern Italy to assume command of the two legions there, and to await Hannibal’s arrival. Though he has been criticized for neglecting the Italian front by sending his army to Spain, a truer appreciation shows that his cautious farsighted conduct and his energetic initiative laid the strategic foundations by which victory was ultimately won.
Hannibal marched up the Rhône to the ‘Island’, where it is joined by the Isère (Isara), and then along this valley to Grenoble. Where he actually crossed the Alps always has been and presumably always will be a matter of uncertainty. The problem is literary even more than topographical. Polybius gives a graphic description, based partly on personal discussions with survivors and supported by a journey to the Alps to verify the geography. But even so his narrative does not fix the pass with certainty, while Livy’s account, which derives in part from Polybius, introduces further difficulties. The majority of scholars look for the pass between the Little St Bernard and Mt Genèvre. But wherever the exact pass was, Hannibal’s exploit has stirred the imagination of mankind.3The actual difficulty of crossing into Italy was not severe, for whole Celtic tribes often moved in this way. The real difficulties arose from the extreme hostility of the Alpine tribes and the fact that the descent was steeper than Hannibal had anticipated and was rendered more perilous by the snow and frost of the advancing autumn. If he had arrived somewhat earlier, many of the dangers would have been avoided. But in the circumstances it was a magnificent triumph of will and discipline over hardship and loss. And so he reached the plains of northern Italy, but with only 26,000 men. The Alps and their inhabitants had taken their toll.
When Hannibal had stormed the chief town of the Taurini (Turin) he was astounded to find that the legions in northern Italy were commanded by Scipio who had travelled nearly 1,000 miles in a month. Scipio crossed the Po near Placentia (Piacenza), hoping to meet Hannibal before his army had fully recovered from the rigours of its journey. He marched along the north bank of the river and encamped on the west of its tributary, the Ticinus. His cavalry engaged Hannibal’s advance guard near Lomello, but was beaten back; he himself was wounded and his life was saved by his son, the future conqueror of Hannibal. A somewhat complicated series of manoeuvres followed, leading up to the battle of the Trebia.4 Wishing to evacuate the open country, Scipio withdrew to Placentia, crossed to the south of the Po, advanced again westwards and encamped at Stradella, where he was less exposed to Hannibal’s cavalry. Meantime Hannibal had advanced to the Ticinus, but found that Scipio had destroyed its bridge. Accordingly he retired westwards along the Po till he was able to cross above Tortona and then advanced towards Scipio and offered battle. But Scipio was forced by the desertion of his Gallic allies to retire to the Trebia just south of Placentia, where he awaited his colleague. Hannibal obtained by treachery the Roman post at Clastidium and then encamped opposite Scipio.
When news had reached Rome that Hannibal was marching against Italy, the African expedition was cancelled and Sempronius, who had captured Malta, was summoned to northern Italy. Leaving a spuadron to protect Sicily, he hastened with his army to Ariminum and then joined Scipio at the Trebia in late November. Contrary to Scipio’s advice Sempronius determined to fight, being buoyed up by a successful cavalry skirmish. On a bitter December day the Roman army was led breakfastless through the Trebia against the enemy. Hannibal’s plan was for his centre to remain on the defensive and his wings to outflank and defeat the enemy, while his brother Mago, who lay in ambush in a scrub-covered gulley, charged out on their rear. All went according to plan, except that 10,000 Romans broke through Hannibal’s centre of Celts and reached Placentia. But two-thirds of the Roman army was destroyed and Hannibal had won the first real battle of the war. Yet the Senate did not despair. The defeat was due to Hannibal’s superior cavalry; the Roman legionaries of the centre had proved their mettle and were safe in Placentia. Winter would interrupt further operations, and next year their legionaries might yet assert the superiority in which they trusted.