At first we were inclined to regard the mining officers--of which we had two--as a sort of nuisance like engineers, trench mortar men, and some others, who were always demanding men for carrying and working parties. But we were not long in finding that they were, like ourselves, necessary evils, and they became welcome guests at our little mess when in the trench. Whenever the trenches approach as close as they did at this point mine warfare becomes inevitable, and it is a game at which it is best to be first. To defend a position against this method of attack one commences a counter-mine at a depth sufficient to take the gallery or tunnel underneath the enemy's one, which, once it is located, is blown in before they manage to get under the defenders' trench. The tunnel or gallery is barely large enough for a man to crawl along on his hands and knees, and must be boarded foot by foot as it progresses to prevent it from collapsing. In this cramped position the sapper wields his pick, a peculiar affair not unlike a harpoon, and scrapes the loosened earth back with a short grubber to another man who removes the earth in sandbags. Progress under such circumstances must be slow, but it is made slower by the necessity of running galleries at right angles to the main tunnel from time to time in an effort to locate the enemy. Here men are posted, while all work is for a time stopped, to listen for the first sounds of the enemy's sappers--the thud-thud of the picks or the "cough" of the man whose lungs seek this relief in the stuffy air of the cramped tunnel. If the enemy is not found, progress is continued forward from both ends of the cross-gallery and the game goes merrily on. About this stage the mining officer will, if you happen to be holding the trench under which he is grovelling, wax eloquent over a crumpled sheet of tracing linen that he presents to your view as a diagram of the workings. It looks like nothing so much as a drawing of the kith and kin of an old and prolific family; but you dare not tell him that, or he will be your enemy for life. Instead you should say, "Ahem!" and "Oh, yes; how clever!"--then he will ask you for only ten instead of twelve men on the night's working party. But once the enemy is located you begin to regard him more seriously, for on his skill depends the life of every man in the trench above, and a false change in direction may mean missing the enemy's tunnel altogether. Sometimes, but not often, the mining is so quietly done that the first sign of the enemy is the sudden collapse of the wall of earth between the two galleries, leaving the rival workers face to face! At other times, and this is a normal occurrence, the enemy are heard to one side or the other, and a small charge of powder is laid and his gallery is blown in, crushing his workers to death, or perhaps merely burying them to perish miserably by suffocation.