In the first chapter of this book I have briefly explained the Imperial theory of the defence of Italy; that theory I have at greater length, and I think for the first time, set forth in a previous work.[13] Here I must very briefly recapitulate in saying that the valley of the Po, the whole Cisalpine Plain between the Alps and the Apennines, was in the Imperial theory, and rightly, the defence of Italy. That defence was barred again upon the inward or southern side by the barren and therefore impassable range of the Apennines,--impassable, that is, save at the eastern extremity, where the Via Emilia ran between the mountains and the sea into the city of Rimini. That narrow pass was commanded and held not by Rimini, which was indefensible, but by Ravenna which, on account of its position in the marshes, could not be taken and scarcely attacked. It was the due and wise recognition of these facts that caused the Emperor Honorius to take up his residence in Ravenna when Alaric crossed the Alps. That city had been the key to the defence of Italy ever since; it remained so now, therefore Aetius went thither gathering his army along the Via Emilia behind the line of the Po to await the final adventure of Attila. Having failed to destroy the Eastern Empire, having failed in his attack upon the western provinces, the only thing that remained for Attila to attempt was the destruction and rape of the soul of all, the citadel of civilisation, Italy and Rome. It was the hardest task of all, therefore in his prudence, and he was always prudent, he had not tried it till now. It was his last throw. It was to fail, and that so contemptibly that his campaigns East and West in comparison seem like triumphs. Like Kaiser Wilhelm II., what Attila lacked in real force he strove to supply with blasphemy and boasting. He was as ill-informed and as ignorant of the real nature and strength of the forces opposed to him as the German statesmen of our day; he exaggerated and relied upon the corruption of the Empire; above all, like the Kaiser, he failed to see that the future frowned against him dark and enormous as the Alps. [Illustration: CISALPINE GAUL AND THE DEFENCE OF ITALY]