Roman intervention in the affairs of Sicily, where Carthage was the dominant power, produced the rupture between the two great states which was bound to come sooner or later. Sicily itself was the scene of the initial struggle, which taught Rome that her victories on land were liable to be nullified by the Carthaginian sea power. She resolved to build a navy, on the plan of adopting boarding tactics which would assimilate a naval engagement to a battle on land. These tactics were successful enough to equalise the fighting value of the respective fleets. The Romans were enabled to land an invading army under Regulus in Africa. Though superior on land, the general's blundering led to a disaster, and for some time misfortune by sea and failure by land dogged the Romans. But Carthage failed to use her opportunity; she did not attempt to strike a crushing blow when she could have done so. But the private energy of Roman patriots at last placed on the seas a fleet which once more turned the scale, whereas it was on land that the brilliant Carthaginian Hamilcar had displayed his genius and daring. The first Punic War gave Rome predominance in Sicily, and a position of maritime equality. Sardinia was added to the Roman dominion, and her provincial administration came into being. She was carrying her expansion farther over Celtic regions, when Hannibal, the son of Hamilcar, hurled himself against her, and came near to destroying her. Hamilcar had conceived the idea of imperial expansion, and given it shape by creating a dominion in Spain; he had looked forward to the life-and-death struggle with Rome that was destined to his son; for which Spain was to be the base. Hannibal, left in control in Spain, deliberately challenged Rome to war. The challenge was accepted, war was declared, and Hannibal accomplished the amazing feat of leading an army of 60,000 men from Spain and effecting the passage of the Alps, while the Romans were landing an army in Spain. In a brilliant campaign, he defeated the stubborn Roman legions at Vercellæ and the Trebia. But success depended not on the winning of victories by an isolated force, but on the disruption of Italy. His superiority in the field was again demonstrated at Trasimenus, but no Italian allies came in. He outwitted Fabius, and then utterly shattered at Cannæ a Roman force of double his own numbers. For a moment it seemed that Italian cohesion was weakening; but the Roman Senate and people were stirred only to a more dogged resolution.