"The idea of blowing up positions that cannot be taken otherwise is by no means a new one. Probably it dates back almost as far as the invention of gunpowder itself. Doubtless, if we only knew of them, there have been attempts to mine the Great Wall of China. It was, therefore, only natural that, when the Austrians had us held up before a position it was vitally necessary we should have, we should begin to consider the possibility of mining it as the only alternative. The conception of the plan did not necessarily originate in the mind of any one individual, however many have laid claim to it. It was the inevitable thing if we were not going to abandon striving for our objective. [Sidenote: Engineering operation of great magnitude.] "But while there was nothing new in the idea of the mine itself, in carrying out an engineering operation of such magnitude at so great an altitude and from a position constantly exposed to intense artillery fire there were presented many problems quite without precedent. It was these problems which gave us pause; but finally, despite the prospect of difficulties which we fully realized might at any time become prohibitive, it was decided to make the attempt to blow up that portion of the summit of the Col di Lana still held by the enemy. [Sidenote: Gelasio Caetani the engineer.] "The choice of the engineer for the work was a singularly fortunate one. Gelasio Caetani--he is a son of the Duke of Sermoneta--had operated as a mining engineer in the American West for a number of years previous to the war, and the practical experience gained in California and Alaska was invaluable preparation for the great task now set for him. His ready resource and great personal courage were also incalculable assets. [Sidenote: Miners from North America.] "Well, the tunnel was started about the middle of January, 1916. Some of my men--Italians who had hurried home to fight for their country when the war started--had had some previous experience with hand and machine drills in the mines of Colorado and British Columbia, but the most of our labor had to gain its experience as the work progressed. Considering this, as well as the difficulty of bringing up material (to say nothing of food and munitions), we made very good progress. [Sidenote: Mining under constant fire.] [Sidenote: Thirty-eight shells a minute.] "The worst thing about it all was the fact that it had to be done under the incessant fire of the Austrian artillery. I provided for the men as best as I could by putting them in galleries, where they were at least able to get their rest. When the enemy finally found out what we were up to they celebrated their discovery by a steady bombardment which lasted for fourteen days without interruption. During a certain forty-two hours of that fortnight there was, by actual count, an average of thirty-eight shells a minute exploding on our little position. [Sidenote: Silencing an Austrian battery.]