ance. Railroads and fairly well-laid highways do indeed traverse
these swamps in various parts, especially in German territory,
but trenches could not be dug in yielding mire. In yet another
feature were the military operations hampered by the nature of the
terrain here; the use of heavy artillery.

We have seen that one of the chief causes of success attending
German attacks in the other theatres of the war has been their
use of heavy guns. But in the fighting before Riga, we shall see
when the Germans seemed on the point of taking that city their
heavy artillery was so handicapped that it was rendered practically
useless. Being restricted by the marshes to an attack over a
comparatively narrow front, they were compelled to leave their
heavy guns behind on firmer soil. The guns which they could take
with them were matched by the Russians; the fighting was, therefore,
almost entirely limited to infantry engagements, in which the Russians
were not inferior to the Germans. Thus, we shall find the German
advance on Riga was stopped before it could attain its object.

In studying the fighting in this part of the eastern front, it
will be seen why the Germans were more successful below Riga, and
why the Russians were compelled to evacuate Vilna. Here is a broad
rise, something like the back of a half-submerged submarine, which
seems to cross the country, where the land becomes more solid. The
armies must move, instead of through marshes, along innumerable
small lakes, most of the lakes being long and narrow and running
north and south, with a fairly thick growth of timber among them,
mostly pine and spruce and fir. In character this section is rather
similar to parts of Minnesota. There are two cities to be conquered
in this drier region, Dvinsk, and, further south, Vilna, once the
chief city or capital of the Lithuanians. We shall see the Russians
thrust back from Koenigsberg, and the heavy fighting shifted over
to this section; yet even here, where the huge guns of the Germans
could find footing, the terrain was not suited to trench warfare,
and every arrival of reenforcements on either side would swing
the lines back or forth.

In studying the military movements in a country of this character,
special attention must be paid to the railway lines. Railways, and
more especially those running parallel to the fronts, are absolutely
necessary to success. In looking, therefore, for a key to the object
of any particular movem