Accordingly Germany decided to get east and put Russia out of the war as she had undertaken nine months before to go west and had tried and failed to put France out of the war. But she was again faced with the fact that failure would expose her to new perils, this time on the west.
For her first attack Germany selected the point in the Russian line between the Vistula and the Carpathians, about Tarnow, where the Russian line stood behind the Dunajec River. If the Russian line should be suddenly broken here, the German General Staff might hope to sweep up all the Russian armies which were facing south and endeavoring to push through the Carpathians.
Just about May 1, 1915, the blow fell and Germany, massing hitherto unheard-of numbers of heavy guns on a narrow front, and using untold ammunition, not merely routed, but abolished Radko Dmitrieff's army (Vol. III, 267-276), and moved rapidly in on the rear of the Russian Carpathian armies. With difficulty these extricated themselves and retired behind the San. (Vol. III, 276.) But they were unable here to withstand Mackensen who had assumed command in all this field, and fell back first upon Lemberg and then upon the Volhynian triangle of fortresses within the Russian frontier. Przemysl fell, Lemberg was lost and Dubno and Lutsk, two of the three Volhynian fortresses, fell. (Vol. III, 276-312.)
Having thus disposed of the Galician armies, Mackensen turned northeast from the San, struck at Lublin and Cholm (Vol. III, 357-365), and through them at Brest-Litovsk, far in the rear of the Russian armies in Poland. At the same time Hindenburg in East Prussia moved south, aiming at Grodno and Vilna, also behind the Warsaw front (Vol. III, 256-361), while a third Germany army invaded the Courland and aimed at Riga. (Vol. III, 337.)
The Russian armies in Poland were thus threatened with complete envelopment; they were caught between the closing jaws of the pincers, which were Mackensen and Hindenburg. For a certain time it was not clear whether the gigantic double thrust might not result in the capture of the whole Russian army in Poland. But this did not happen. Warsaw was evacuated (Vol. III, 356), Ivangorod, Novo Georgievsk, the fortresses along the Bobr-Narew-Niemen barrier fell (Vol. IV, 176-181), but the Russian armies drew back upon Riga, Vilna, and Brest-Litovsk. (Vol. IV, 186-188.)
October 1, 1915, at the End of the Russian Retreat.
At Brest-Litovsk there was only a brief halt and then the Russians resumed their retreat upon Pinsk and the Pripet Marshes. Behind the Dvina from Riga to Dvinsk the northern army stood fast. But the central armies, retiring upon Vilna, were nearly trapped and once were actually cut off by German cavalry. (Vol. IV, 193-223.)