broad, mud-colored river, dotted with a number
of low islands along its center. Belgrade, where the first shots
of the war were fired, is located on rather high ground, backed
by a semicircle of low hills in its rear. But opposite all is flat
and, in places, marshy. Modern guns could, of course, keep up an
effective fire across the river at this point, as in fact they
did before the actual invasion of Serbia began, but the conditions
for a crossing are not favorable. It was from the west, from the
Bosnian side, that the actual attack was made.

Just below Belgrade the river Save, shallower and narrower, empties
into the Danube, forming the frontier westward, past Shabatz, to
Ratcha, where the Drina, flowing down from the Macedonian highlands
northward, joins it, forming the western frontier between Bosnia
and Serbia.

The Drina, where much fighting occurs, is no ordinary waterway,
no mere mountain stream, though it lies in a mountainous country.
Before reaching its junction with the Save it is fed by many important
tributaries. Ever swift, often torrential, it has washed out a bed
of imposing width, and by a constant cutting out of new courses
has created a series of deltas. It was one of the largest of these
islands, that of Kuriachista, between Losnitza and Leschnitza,
that the Austrians chose as a base for their first invasion. From
this point up and around to Shabatz lies the bloody field of the
Austro-Serbian battles.

A description of this section, in brief at least, is necessary to
an understanding of the three Austrian invasions made here, and
all three of which failed disastrously. North and west of Shabatz
lies the great plain of Matchva, bounded on its east and north
by the Save and by the Drina on the west. It is a rich, fertile
land, but much broken up by woodland. To the southeast a rolling
valley is divided by the River Dobrava, while due south the Tzer
Mountains rise like a camel's back out of the plain and stretch
right across from the Drina to the Dobrava. The southern slopes of
Tzer are less abrupt than those on the north and descend gradually
into the Leschnitza Valley, out of which rise the lesser heights
of the Iverak Mountains. Both these ranges are largely covered
by prune orchards, intersected with some sparse timber.

This is a region of natural fortifications. Descending southward
again, the foothills of Iverak are lost in a chain of summits,
which flank the right bank of the Jadar River