Imagine, since you have never been there, a seemingly endless succession of ranges and peaks which have assumed the most extraordinary and fantastic forms. The mountains are broken up into every imaginable shape. Here and there they rise at a bound in the form of slender peaks; elsewhere they assume the form of gigantic steps or pyramids or indented crests, sometimes like a saw, at others like a trident. Through this land of towering, snow-clad summits, mighty gorges, rugged precipices, and apparently bottomless abysses, into which the unwary scout might at any moment find himself precipitated, we soldiers and engineers of the Italian army had steadily fought our way. No one, gazing on these summits held by our enemies, would ever have thought it possible to dislodge them. And yet, one by one, they fell into our hands--with the single exception of the Col di Lana, a supreme peak and pass in the Upper Cordevole Valley which, at the altitude I have named, commands the great highway through the Dolomites. On this topmost peak the Austrians had found a last refuge. Daily--almost hourly, indeed--they sent down upon us an avalanche of boulders and hand-grenades. In spite of this we managed on one occasion to gain a foothold, but only for a short time. A withering fire from artillery and machine-guns, placed on the encircling heights, forced us back to the security of our own trenches, some fifty yards below; and there we had been, at the time my story opens, for many weeks, faced with the eternal problem--how to dislodge the enemy from the steel-clad crest of the mountain. Suddenly the meditative silence into which we had fallen was broken by Don Gelasio Caetani, a young engineer who is the son of the Duca di Sermoneta and an English lady. Well known for his patriotism and professional ability, we knew that anything he might have to say would be well worth listening to, so at the sound of his voice we all looked up. "_Ho un idéa!_" ("An idea occurs to me!") he said, slowly and impressively. "I was day-dreaming of my native Naples and Vesuvius," he added. "To a Neapolitan, Vesuvius is everything. He regards it as possessing almost a personality, endowed with life and thought. He watches it, year after year, as I have done, and notes the changes its form has undergone through successive eruptions. The thought of Vesuvius gave me my idea. What do you say, _amici_, if we try and convert the Col di Lana into an artificial volcano?" Had Don Gelasio been other than what we knew he was--a man noted for extreme fertility of invention and resource--we might have been inclined to laugh at him. But we were all too well aware of his seriousness of mind to treat his idea as an idle fancy, and as one man we voiced a request for an explanation of the ways and means towards the proposed end.