On the French and British side also, underground defense works were of a most scientific and elaborate character. Trench warfare has become an art. Away from the seat of war the importance of the loss or the gain of a trench is measured by yards. If you are in trenches on the plain, where the water is a few feet below the surface, and all the area has been used as a cockpit, you would wonder how any trench can be held. If, on the other hand, you were snugly installed in a deep trench on a chalk slope, you would wonder how any trench can be lost. Any real picture of what a trench is like cannot be drawn or imagined by a sensitive people. It is, of course, a graveyard--of Germans and British and French. Miners and other workers in the soil drive their tunnel or trench into inconceivable strata. They come upon populous German dugouts, corked by some explosion perhaps a year ago. They are stopped far below ground by a layer of barbed wire, proved by its superior thickness to be German. Every yard they penetrate is what gardeners call "moved soil." It is of the nature of a fresh mole heap or ants' nest, so crumbled and worked that all its original consistency has been undone. A good deal of it doubtless has been tossed fifty feet in the air on the geyser of a mine or shell explosion. It is full of little bits of burnt sacking, the debris of sandbags. Weapons and bits of weapons and pieces of human bodies are scattered through it like plums. The so-called trench may be no more than a yoked line of shell holes converted with dainty toil and loss to a more perpendicular angle. And the tangled pattern of craters is itself pocked with the smaller dents of bombs. There are three grades of holes--great mine craters that look like an earth convulsion themselves, pitted with shell holes, which in turn are dimpled by bombs. Imagine a place like the Ypres salient, a graveyard maze under the visitation of 8,000 shells falling from three widely separate angles, and some slight idea may be formed of nearly two years' life in the trenches. It is an endless struggle for some geographical feature: a hill, a mound, a river, or for a barn or a house. At Ypres, indeed, the German and British lines have passed through different sides of the same stable at the same time. The competition for a hill or bluff is such that in many cases, as at Hill 60, the desired spot, as well as the intervening houses and even woods, have been wiped out of existence before the rival forces.