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 crossing the Aa at Mitau and establishing their positions to the east of that city, they were unable then, and in fact during the following months, to approach closer to Riga at that point, so that a salient was formed west of Riga, which at its widest point was over twenty miles distant from this point. Just south of Mitau, the south side of this salient bent almost straight to the east for a distance of thirty miles until it reached Uexkuell on the Dvina, about twenty miles southeast of Riga. From there the line followed almost exactly the east bank of the Dvina, passing through the important towns of Friedrichstadt and Jacobstadt, from where it bent due south, gradually drawing away to the west of the Dvina River and passing west and southwest of Dvinsk at a distance of about ten miles. All along this line considerable fighting took place throughout September, 1915, as has already been narrated. During September 21-22, 1915, this fighting was especially severe west and southwest of Dvinsk, where the Germans were making unsuccessfully desperate efforts to break the Russian lines and get within striking distance of Dvinsk. However, although they managed to maintain their own lines against all Russian attacks and to gather in some 5,000 prisoners, they could not break the Russian defensive.