Midwinter was not, of course, the time to see anything of the real effects of the great explosion, for the huge crater torn by the latter was drifted full of snow, and snow was also responsible for the complete obliteration of the countless thousands of tons of _débris_ that had been precipitated down the mountain side. A dizzy climb up the ladder-like stairway, and a crawling clamber through a hundred yards of the winding tunnel from the rock chambers which had housed the compressors, revealed about all that was visible at the time of the preparations and consequences of the mighty work; but a peep from the observation port of a certain cunningly concealed gun-cavern discovered a panorama which gave illuminative point to the concluding words of the artillery officer who, pointing with the shod handle of an ice-pick, explained the situation to me from that vantage. “So you see,” he had said, “that the Castelletto in the enemy’s hands was a stone wall which effectually barred our further progress; while in our hands it becomes a lever which--whenever we really need to take them--will pry open for us positions of vital importance. We simply _had_ to have it; and so we took it in the one way it could be taken. * * * * * “Save for his Alpini uniform Lieutenant Malvezzi, when I met him at dinner that evening, might well have passed for the typical musician of drama or romance. His skin and hair and eyes were dark, and his long nervous fingers flitted over the paper on which he sketched various phases of the Castelletto work very much as those of a pianist flit above his ivory keys. The dreamy, far-away look in his eyes was also suggestive of the musician, but that I had long come to recognise as equally characteristic of all great engineers, the men whose tangible achievements are only the fruition of days and nights of dreaming. “Where shall I begin the story?” he had asked as the diners in the regimental mess began to resolve into little knots of threes and fours over coffee and cigars; and I had suggested that he take it up where his report left off. “That stopped just as things began to happen,” I said. “Now tell what _did_ happen.” The Tenente laughed a laugh suggestive of rueful reminiscence, and a smile ran round among those of the officers who had heard and understood my words. “So far as I am concerned,” he replied, “that covers about five minutes of activity--five minutes for which we had been preparing for six months. You understand that we had constructed a branch tunnel through which our men were to rush and occupy the crater as soon after the explosion as possible.