y small sector offers other
natural advantages in the form of a number of smaller streams, the
defense of which is greatly assisted by the marshy condition of their
banks and the heavy growth of underbrush to be found there.

Rovno, the largest of the three cities, with about twenty thousand
inhabitants, was first fortified in 1887, and as a railroad junction
is even more important than either Lutsk or Dubno. Its fortifications
are built to serve as a fortified bridgehead. They amount to seven
forts of which five are located on the left bank of the Ustje and two
on the right. These forts were built in the form of a semicircle, at a
distance of four to six miles from the city itself and with a
circumference of approximately twenty-five miles. Originally this
group of fortresses undoubtedly was intended to act as a basis for a
Russian invasion of Galicia and Hungary rather than as a means of
defense against an invasion from these countries. And, indeed, in the
earlier part of the war, when the Russians forced their way into
Galicia and to the Carpathian Mountains, they fulfilled their purpose
with greater success than they were destined to achieve now as a means
of defense.

CHAPTER XXV

FIGHTING ON THE DVINA AND IN THE DVINA-VILNA SECTOR

At the time Warsaw fell, in the beginning of August, 1915, the eastern
front north of the Niemen extended as follows: Starting on the western
shore of the Gulf of Riga, at a point about twenty miles west of Riga
and about thirty miles northwest of Mitau it ran in a slightly curved
line in a southeasterly direction to the town of Posvol on the Musha
River, passing just west of Mitau and the River Aa, about ten miles
west of Bausk. From Posvol a salient with a diameter of about twenty
miles extended around Ponevesh on the Libau-Dvinsk railroad, with its
most eastern point a few miles west of Kupishki on the same railroad
line. From there the southern side of the salient passed through
Suboch and Rogoff to Keydany on the Nievraza, and along the banks of
that stream to its junction with the Niemen, about five miles west of
Kovno.

In a preceding chapter we have learned how this line was pushed back
by the Germans during and following the drive on Kovno and Vilna.
After Vilna's fall on September 18, 1915, the Germans had advanced
along the western shore of the Gulf of Riga to Dubbeln, about ten
miles west of Riga, at the Aa's delta. But, although the Germans
succeeded in cross