Throughout the following days the story of the Russian retreat and the German-Austrian advance changed little in its essential features. As fast as roads permitted and as quickly as obstacles in their way could be overcome, the forces of the Central Powers advanced. With equal determination the Russian troops availed themselves of every possible, and quite a few seemingly impossible, opportunities to delay this advance. Every creek was made an excuse for making a stand, every forest became a means of stalling the enemy, every railroad or country road embankment had to yield its chance of putting a new obstacle into the thorny path of the advancing invader. Whenever the latter seemed to ease up for a moment, either to gain contact with his main forces or to rest up after especially severe forced marches, the Russians were on hand with an attack. But just as soon as the attack had been made the Germans or Austrians or Hungarians, or all three together, were ready to forget all about the temporary let-up and were prepared to meet the attack. Then once more the pursuit would begin. During the drive on Brest-Litovsk, covering practically all of August, 1915, after the fall of Warsaw, the operations of Von Mackensen's southern group were so closely connected and intertwined with those of the central group that they have found detailed consideration together with the latter. During all this time the extreme right wing in Eastern Galicia did comparatively little beyond preventing an advance of the Russian forces at that point. With the fall of Brest-Litovsk, however, and the beginning of the Russian retreat along the entire front, activities in the southeastern end of the Russo-German-Austrian theatre of war were renewed. On August 28, 1915, German and Austro-Hungarian forces under Count Bothmer broke through the Russian line along the Zlota-Lipa River, both north and south of the Galician town of Brzezany, about fifty miles southeast of Lemberg, and in spite of determined resistance and repeated counterattacks drove the Russians some distance toward the Russo-Galician border. At the same time other parts of Von Mackensen's army successfully attacked the Russian line at Vladimir Volynsky, a few miles east of the Upper Bug and somewhat north of the Polish-Galician border. The combined attack resulted in a gradual withdrawal of the entire Russian line as far as it was located in Galicia, aggregating in length almost 160 miles. These operations alone netted to the Austro-Germans about 10,000 Russian prisoners. This attack came more or less unexpectedly, but in spite of that was carried on most fiercely. By August 30, 1915, the right wing had forced the Russians back to the river Strypa and was only a few miles west of Tarnopol.