From every possible line of human enterprise the Germans, according to Russian reports, apparently tried to learn lessons which might become applicable in these near-arctic conditions on the east front. Having been taught by the previous winter's experience the impossibility of trench digging, they promptly organized extensive mining detachments among their engineering troops, augmenting the latter in great quantities by soldiers from other branches of their general service who, from their experiences in times of peace, had become particularly adaptable to such work. These mining troops, later on in the winter, were to creep forward under the protection of night's shadows and blast with dynamite those trenches that were absolutely essential for cover of advancing troops and that could not be dug in the frozen ground with more simple tools. Long before this, however, while winter had not yet shown its full severity, these troops were busily occupied with the preparation of land mines, which were to act as substitutes for barbed-wire entanglements when freezing snow, piling up many feet high, rendered the latter useless. Previous experience, too, had taught that, when such weather conditions arose, the immense quantities of snow that fall in these regions not only completely covered barbed-wire entanglements, but as repeated snowstorms thickened the mass day by day, and sleet and thaw, caused by an occasional hour's sunshine, hardened it, made it even possible for the enemy's forces to advance securely on it in spite of, and on the very top of, all barbed-wire obstacles. Throughout the first winter of the war the Germans had also used ski detachments. Most of these were employed in the mountainous regions of the western front. But small troops had been sent to East Prussia and had proven themselves very valuable there. Again and again Russian troops, attempting operations on ground covered with two or three days' snowfall, had sunk to their waists and chests into the snow and had become easy prey to attacks made by German soldiers on skis. So the Germans early in the fall, when certain parts of south Germany and Austria, covered with high mountains, lend themselves admirably for ski practice, had sent time after time detachments of carefully selected infantry troops to these regions and had made ski experts out of them. Sledges too--large and small--had been provided in quantities, because they had proven their value as means of transporting men and supplies where all other means had failed absolutely. With the approach of real winter all these comparatively new features of warfare were put to use. Of course the Germans were by no means the only ones to profit from past experience and from the modern advance of the sciences and mechanical industries. But from all reports it is clear that they outdid the Russians in inventiveness as well as in the thoroughness and extent of their preparations.