ation 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.

"Jack Frost" also definitely stopped regular fighting. With its
arrival war at the eastern front deteriorated into more or less of a
guerrilla war. Instead of attempts to break through the line by miles,
both sides settled down to a bitter contest for choice pieces of
ground here and there. An exchange of a bit of high ground for a
nasty, damp trench in a bog was considered quite a victory. The
capture of a small supply train by a small detachment that had managed
to sneak through the