Foiled in their grandiose plans in the West, the Germans were forced to rest content with their valuable territorial gains in France and Belgium, and remain on the defensive there while they turned to the more threatening situation on the Eastern front. As already noted, the Germans had under-estimated the rapidity of the Russian mobilization. They had not anticipated an offensive on that front until they could spare as many reserves as necessary from the West, and the forces left to guard their vulnerable frontier of East Prussia were as inadequate to stay the unexpected advance which the Grand Duke Nicholas, who was in supreme command of the Russian armies, ordered under Generals Rennenkampf and Samsonoff, as were the Belgians to prevent the march of the Germans across their territory. By 25th Aug. the Russian armies, whose advance had begun as early as
the 7th, had pushed so far ahead that all East Prussia seemed in danger of falling into their hands. General von François, commanding the German troops, had been driven into Königsberg, the cradle of the Prussian monarchy; Gumbinnen, Justerberg, Allenstein, Soldau, had all been captured; and the hopes of a flight to Berlin before the Russian 'steam-roller'—too often raised in the early stages of the war—seemed not unlikely to be realized.
Germany's hour of danger, however, produced the man who was destined to play a ruling part in the remaining phases of the struggle—Paul von Hindenburg, a veteran of the Franco-Prussian War, then on the retired list. Hindenburg knew the topography of East Prussia by heart, and had commanded army corps in manœuvres along that frontier for many years. Appointed at this critical moment to supersede General von François, he collected 160,000 men from every available source, and by means of Germany's unequalled strategic railway system had concentrated them in a favourable position between Allenstein and Soldau for delivering the blow which would cut the communications of the southern army under Samsonoff, and smash it piecemeal in the treacherous marshes of the Masurian Lakes, the tracks through which, though well known to Hindenburg, were a veritable tangle to the Russians.
Tempted by their initial triumphs, the Russians had themselves courted disaster by placing themselves in precarious positions. Samsonoff's southern army had not only lost touch with the northern force under Rennenkampf, which had occupied Insterberg on the 23rd on its march on Königsberg, but had also failed to secure either Allenstein or Soldau. Hindenburg was quick to seize every advantage, and his lethal thrust on the 26th, when he retook Soldau and outflanked the Russian left, was followed by a similar enveloping movement on their right before they realized what had happened. Masses of German guns came up and completed the move. Too late the Russians fled along the only road left open to them—by way of Ortelsberg and Johannisberg, across a narrow slip of land between the marshes. Save for little more than one corps, which succeeded in escaping along this route before it was closed, practically the whole of Samsonoff's army was wiped out in this decisive battle of Tannenberg, as the victors named it. Samsonoff himself was killed by a shell on 31st Aug. Altogether the Russians lost in killed and wounded some 30,000; no fewer than 90,000 were taken prisoners.
Hindenburg, whose Chief of Staff was General von Ludendorff—already distinguished in the war as the leader in the assault on Liége—at once became a national hero throughout Germany. The Central Powers, however, had little further cause for rejoicing on the Eastern front in 1914, once Hindenburg had been enticed to the Niemen by the rapid retreat of Rennenkampf after the Tannenberg débâcle. The Grand Duke Nicholas had sent General Ruzsky from Galicia to retrieve the situation, and the new leader made as good use of the Niemen River—a formidable obstacle to cross with its width of some 200 yards—as Hindenburg had done of the Masurian Lakes. The operations, which ended in the failure of the Germans to cross the river, and their heavy defeat at Augustovo after a sanguinary nineteen days' battle beginning on 1st Oct., restored confidence to the Russian army.
General Ruzsky had already made his mark in the opening campaign in Galicia, where the Austro-Hungarian armies, after invading Russian Poland at the opening of the war, were driven back in a series of mighty battles which left the Russians in possession of Lemberg and all Eastern Galicia. Brussiloff was meantime sweeping on towards the Carpathian passes, while Ivanoff, commanding the Russians in Poland, forced back the invading armies under Dankl and the Archduke Joseph Ferdinand beyond the Vistula and Cracow. Przemysl alone held out in Galicia, and this was invested by the Russians towards the end of September, when the Germans, far to the north on the Niemen, were rapidly losing the advantage and prestige they had won at Tannenberg. Hence Germany's increasing need for help from the Western front.
In order to check the Russian advance on the key position of Cracow, Hindenburg was now called from the East Prussian front to take over the supreme command of the unified German and Austro-Hungarian armies in a crushing blow at the Russian centre in Poland. Hindenburg's advance on Warsaw was planned by his Chief of Staff, Ludendorff, to keep pace with a parallel advance of the Austro-German armies in the south, intended to raise the siege of Przemysl and turn the Russians out of Lemberg. The combined forces of the Central Powers amounted to some two million men, outnumbering the Russians by at least half a million, and outgunning them completely. It speaks volumes not only for the fighting spirit of the Russian armies at this period of the war, but also for the strategy inspired by the Grand Duke Nicholas, that in both the first and second battles of Warsaw the combined Austro-German armies were both outfought and outmanœuvred. "The Grand Duke Nicholas", to quote from Lord French's tribute to his leadership some years later, "proved that he possessed that highest of military gifts—the power of renunciation,
of 'cutting down', of sacrificing the less essential for the more."
Foreseeing the danger of Hindenburg's march on Warsaw, the Grand Duke promptly recalled the first great Russian advance on Cracow, and the armies concerned were safely withdrawn behind the Vistula and the San before the enemy could cut the main line from Warsaw to Kiev. Ivanoff's army in Galicia conformed to the general movement. While thus suggesting the abandonment of Poland and a general retirement on Brest-Litovsk, the Grand Duke placed a field army in defence of Warsaw, assisted by Japanese heavy artillery, and prepared a great counter-offensive from the north-west, under cover of the guns of Novo Georgievsk.
Hindenburg's main blow was delivered at Josefov, higher up the Vistula, with the intention of taking Warsaw in the rear. Ruzsky had been brought down to take command at Josefov, and here repeated the disaster which he had recently inflicted on the Germans at Augustovo. This time he lured the enemy across the river before falling on him in difficult country, and cut him to pieces. Rennenkampf was equally successful with the counter-attack from Novo Georgievsk, striking so hard that the German left centre was forced back from the Vistula with heavy losses. With both flanks turned—for Ruzsky had followed up his victory by himself crossing the river at Novo Alexandriev, and driving the Germans back first to Radowa (15th Oct.) and then to Kielce (3rd Nov.)—Hindenburg had no alternative but to seek safety within the German frontier, and prepare another counter-stroke. The only success of the first advance on Warsaw was achieved by the Austrians under the Archduke Joseph Ferdinand and Generals Woyrsch and Dankl, who succeeded in temporarily relieving Przemysl and recovering Jaroslav. Hindenburg's retreat, however, compelled them to withdraw in conformity to that movement. Przemysl was again invested, the Austrians again fell back in Galicia, and the Russian advance on Cracow was renewed, the Grand Duke Nicholas having set his heart on reaching that convenient gateway both to Berlin and Vienna before the end of the year.