an attempt on the fortress of Ossowiec proved equally futile, because
the Germans could find no ground within range solid enough to bear the
weight of their artillery. The inevitable retreat began on the 27th,
and it was sadly harassed by the pursuing Russians, especially in the
forest of Augustowo, where Rennenkampf claimed to have inflicted
losses amounting to 60,000 men in killed, prisoners, and wounded. By 1
October the Russian cavalry was again across the German frontier, and
Hindenburg was called south to attempt in Poland to frustrate the
Russian advance on Cracow which his turning movement in the north had
failed to check.

The call was urgent, for the conquest of Galicia portended disaster to
the Central Empires. Cracow was a key both to Berlin and Vienna; its
possession would turn the Oder and open the door to Silesia, which was
hardly less vital to Germany than Westphalia as a mining and
manufacturing district. It would also give access to Vienna and
facilitate the separation of Hungary, and all that that meant in the
Balkans, from the Teutonic alliance. Even without the loss of Cracow,
that of the rest of Galicia was serious enough; her oil-wells were the
main sources of the German supply of petroleum, and her Slav
population, once assured of the solidity of Russian success, would
throw off its allegiance to the Hapsburgs and entice the
Czecho-Slovaks on its borders to do the same. These prospects were not
visionary in September 1914. Jaroslav fell on the 23rd and Przemysl
was invested. Russian cavalry rode through the Carpathian passes into
the Hungarian plain, and west of the San patrols penetrated within a
hundred miles of Cracow. In her own interests as well as in those of
her ally, Germany was compelled to throw more of her weight against
the Russian front. The German and Austrian commands were unified under
Hindenburg, and having failed on the north he now tried to stop the