Back the Germans and Austrians forced their retreating enemy during the following days, although the pursuit lost a little in force and swiftness. For the troops which were engaged in these operations had been steadily on the move practically ever since the attack on Warsaw began. On September 6-7, 1915, the Russians again made a stand on a wide front east and south of Grodno. This line stretched south from the Niemen near Mosty to Volkovysk, then southeast to Rushana, thence east of the Pushany Marshes across the Jasiolda River near Chenisk to Drohichyn, on the Brest-Litovsk-Pinsk railroad. On the German and Austrian side these engagements were fought by the armies of Prince Leopold of Bavaria and Field Marshal von Mackensen. At the same time troops belonging to Von Hindenburg's group attacked a newly formed Russian line farther north which extended from Volkovysk in a northwesterly direction to the village of Jeziory and the small lake on which the latter is situated, just north of Grodno. Volkovysk itself and the heights northeast of it were stormed by the Germans on September 7, 1915, on which occasion again almost 3,000 Russians were captured by the Germans.
During the next few days the left wing of this army group fought in close cooperation with the right wing of Von Hindenburg's army along the upper Zelvianka, a southern tributary of the Niemen. The rest of Prince Leopold's army were making the Kobryn-Minsk railroad their objective and were fighting on September 9, 10, and 11, 1915, for possession of the station at Kossovo.
While Von Hindenburg's army group was occupied with the drive on Vilna and Von Mackensen's forces advanced against Pinsk, Prince Leopold's regiments, as we have learned, fought continuously in the sector between the Niemen and the Jasiolda Rivers. The problem assigned to them apparently was that of gaining the Vilna-Kovno railroad in order to cut off the Russian retreat, and by the time Vilna fell, September 18, 1915, they had just succeeded in forcing a crossing over the Shara River, which runs practically parallel to the Lida-Baranovitchy section of the Vilna-Kovno railroad. In a way this gave them command of that section; but they first had to cross the country between the Shara and the railroad, over a width of about twenty miles. Although they were reported on September 19, 1915, as participating in the pursuit of the retreating Russians, they seem to have arrived just a little too late to capture large numbers of them. In fact, not until September 20, 1915, were they reported actually at Dvorzets, on the Vilna-Kovno railway, while on that day the right wing of this army was fighting west of Oshoff, which, indeed, is to the east of the Brest-Litovsk-Minsk railway, but still a considerable distance (about twenty-two miles) west of Moltshad, a little to the southeast of Dvorzets; stormed Ostroff, and crossed the Oginski Canal at Telechany, after first throwing the Russians across it. These operations netted some 1,000 prisoners. September 22, 1915, brought their left wing about ten miles farther east at Valeika, while farther south the fighting continued in the same locality as on the previous day during the following days. By September 23, 1915, the left wing again had advanced about ten miles along the Servetsh River at Korelitchy, as well as the Upper Shara, east of Baranovitchy and Ostroff. The Russian resistance along this river was maintained during September 24, 1915, although the Germans gained its eastern bank south of Lipsk.