Hannibal conceived of the war as a struggle against a state of overwhelming strength which by its mere existence made free action impossible for any other. He was perfectly well aware that he alone, with the army of twenty thousand seasoned veterans absolutely devoted to him, and the six thousand cavalry, which he had led into Italy, might defeat Rome in the field but could never overthrow her; in spite of any number of victories no attack on the capital could end otherwise than as the march of Pyrrhus on Latium had ended. The Celts of the Po valley served to swell the ranks of his army but were of no consequence to the ultimate issue. Hannibal sacrificed them ruthlessly in every battle in order to save the flower of his troops for the decisive stroke. He made attempts again and again to break up the Italian confederacy, and after Cannæ, the greater part of the south of Italy, at least as far as Capua, went over to his side; but middle Italy, the heart of the country, stood by Rome with unfaltering loyalty. Carthage itself could do little, and its government would not do much; the Second Punic War is the war of Hannibal against Rome; Carthage took part in it only because and so far as she was ordered to do it. The fleets which Carthage sent against Italy could do nothing in face of Rome’s superiority at sea; no serious naval engagement was fought throughout the whole war. A more conclusive result might perhaps have been arrived at if Hannibal had been able to keep open his communication with Spain, and if his brother Hasdrubal could have followed him immediately, so making it possible for them to sweep down upon Rome from both sides. It was a point of cardinal importance, and one which from the outset paved the way for the ultimate victory of Rome, that when the consul Publius Scipio found himself unable to overtake Hannibal on the Rhone in the August of 218, he hastened in person to Italy, where there were troops enough to set army after army in array against Hannibal; but by a stroke of genius he despatched his legions to Spain and thereby forced Hasdrubal to fight for the possession of that country instead of proceeding to Italy. By the time that Hasdrubal, having lost almost the whole of the peninsula to Publius Scipio the Younger, resolved in 207 to abandon the remainder of the Carthaginian possessions and march into Italy with his army, it was too late; he succumbed before the Romans at the Metaurus. Complete success could only have been attained if Hannibal had succeeded in drawing the other states of the world into the war and carrying them with him in a decisive attack upon Rome.