, that tributary of
the Drina River from which the first big battle takes its name.

From the left bank of the Jadar, from its junction with the Drina
to Jarebitze, a great rolling level stretches south until the high
Guchevo Mountains, stretching in southeasterly direction, rise
abruptly and hide the Bosnian hills from view. From there, southward,
the country is extremely mountainous, even the highways being blasted
out of the sides of the precipitous mountains along the innumerable
ravines through which run watercourses which, though almost dry
in summer, burst into torrential streams after the snows begin
to melt in the higher altitudes.

Naturally in such a country roads are of prime importance in military
operations. A few built and maintained by the state are in excellent
condition and practicable in all sorts of weather. But for the
rest communications consist of bridle paths and trails over the
mountains.

As has been stated, the great highway from Belgrade to Saloniki
is the key to all military operations in the Balkans; nor is this
case any exception. A study of the map will show how this big,
underlying fact entered into the plans of the first three attempts
at invading Serbia. Naturally, had facilities been convenient at
Belgrade, that would have been the point from which to advance.
The next possible point was over the Drina, because it was not
so wide or so deep.

Bosnia and Herzegovina at the beginning of the war were sparsely
served by railroads. But for the purpose of an invasion of Serbia
the lines running to Tuzla in the north and to Vishegrade and Uvatz
in the south were of much strategic importance. Moreover, unlike the
Hungarian plain opposite Belgrade, the country is so mountainous
and well wooded that great bodies of troops could be moved about
without being observed. We now come to the main reason why this
point was chosen, next to Belgrade. Though we shall see that they
did not reach it at their first attempt, there is no doubt that
the main objective of the Austrians was the little town of Valievo,
lying some distance back from the Jadar and the field of battle.
For at Valievo is the terminus of a light railway which joins with
the main line running from Belgrade down to Saloniki. The Teutons
were in a hurry to open this highway, for it meant opening a means
of communication with the Turks, who were to become, and later
did become, their active allies. These are political matters of
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