The Austro-German plan contemplated a defensive fight on the north, in East Prussia, and an offensive campaign from the south, aimed at Lublin and Brest-Litovsk. The Russians on their side planned an immediate invasion of East Prussia from Warsaw and Kovno and a far more considerable offensive into Galicia from the Rumanian boundary to Rowno. The objective of the northern operation was the conquest of the whole of Prussia east of the Vistula, that of the southern the capture of Lemberg and the conquest of all Galicia. Combined, these two movements would abolish the Polish salient and give the Russian right flank the protection of the Baltic, the left the cover of the Carpathians. Only then could there be any safe advance by the center through Poland upon Posen and Breslau and thence upon Berlin.
Russian mobilization was more rapid than Russia's allies could have hoped for and it wholly confounded the Germans. While the Battle of the Marne was still two weeks off Russian forces were sweeping west from the Niemen and approaching Königsberg, a second army was striking north from Warsaw. East Prussian populations were fleeing before the invaders and a German disaster seemed imminent.
The genius of Hindenburg, who now appeared upon the eastern battle ground, saved the situation. Gathering in all his available forces and leaving the Russian army coming from the Niemen almost unopposed, he caught the Warsaw army in the swamps about the frontier in the last days of August and, thanks to his generalship and heavy artillery, destroyed a Russian army. Tannenberg was a great victory and it saved East Prussia. The Niemen army had to retreat rapidly to escape destruction. At the time, it was asserted that the Russian invasion had compelled the Germans to draw upon their western front to meet the thrust and thus to weaken their armies in advance of the decisive battle. This is not now believed to be true, but there is no doubt that it drew reserves who might otherwise have gone to the west or to the south.
Tannenberg was a victory which filled the world with its splendor, but it merely disguised for the moment the far more considerable Austrian disaster to the south. One Austrian army had crossed the frontier and approached Lublin, another had advanced east from Lemberg. Upon the Lemberg army the full weight of the Russian thrust now fell and the army was promptly routed, driven through Lemberg and west of the San or across the Carpathians. The force that had approached Lublin was thus left in the air and succumbed to a series of disasters, which culminated in the terrible defeat of Rawa-Ruska. Meantime the Austrian troops, which had invaded Serbia were routed in the Battle of the Jedar, which preceded the other Austrian disasters and was, in fact, the first considerable triumph for the Allies in the whole war.
AUSTRIAN PERIL
Austria was now in dire straits and her whole military structure seemed on the point of crumbling. Russian armies flowed west through Galicia and approached Tarnow, Przemysl was isolated, tens of thousands of prisoners, innumerable guns and vast quantities of stores fell to the victors. While the great German attack upon France was failing, Russia seemed on the point of achieving against Germany's ally what Germany had failed to achieve against France.
Germany was now compelled to intervene. At the moment when she was organizing her final effort in the west and sending her best troops to hack their way to Calais, she had to divert other troops to the east. Hindenburg undertook a new offensive, this time from the Silesian frontier, and pushed with great rapidity to the very suburbs of Warsaw. He only failed by a narrow margin, Siberian troops coming up just in time to save the Polish capital, and Hindenburg, now outnumbered, conducted a swift and orderly retreat to the frontier. But his intervention had disorganized the Russian campaign in Galicia and Russian armies there had been compelled to retreat and send reenforcements north.
Hindenburg's retreat was a signal for a fresh Russian advance, this time the czar's forces reached the gates of Cracow and began to crowd through the Carpathian passes and sweep down into the Hungarian Plain. Przemysl was again invested, Russian troops for the first time entering German territory west of the Vistula. It was necessary for Germany to intervene again.
This time Hindenburg was more successful. He had retreated upon Cracow and Breslau; gathering up his armies he transported them rapidly to the north by strategic railways, brought them back into Poland south of the Vistula, interposed between the Russians and Warsaw and very nearly repeated at Lodz his great success of Tannenberg. But this time the Russians after desperate fighting won clear, and fell back to the lines in front of Warsaw, which they were to hold for so many months. At the same time they retreated in Galicia from before Cracow to Tarnow and stood behind the Dunajec River. Austria was saved again, but having, in her extreme peril recalled some of her corps from an army engaged in a new invasion of Serbia, that army was routed and well-nigh destroyed.
GERMANY'S SECOND OFFENSIVE
From December to April the eastern campaign lacked decisive circumstances. In the north Hindenburg won a new and splendid victory at the Mazurian Lakes, expelling a Russian army which had renewed the invasion of East Prussia. In the south the Russians steadily pushed the Austrians back into the Carpathians, took Przemysl with more than 125,000 prisoners, and as spring came seemed on the point of crowning the Carpathians and descending into the Hungarian Plain.
But the Germans were already organizing their second great offensive. They were raising new armies, collecting fresh stores of ammunition and preparing for a thrust against Russia as gigantic as that against France, with the deliberate purpose of eliminating Russia from the war. There was no longer any chance of a Napoleonic success in Europe. But if Russia were eliminated, they could still hope to win a peace that might leave them Belgium. Some portion of their plans was spoiled almost as the spring campaign opened, by the entrance of Italy on the Allies' side, but Italy came too late to save Russia from the disasters that had begun.
The German plan of campaign was simple. Hindenburg was to strike east and south from East Prussia at the Russian lines along the Niemen-Bobr-Narew. Mackensen, having pushed the Russians out of Galicia, was to strike north through Lublin and toward Brest-Litovsk. A new army was to invade Courland and aim at Riga. It was the German hope that the main Russian masses would be caught and enveloped by Hindenburg and Mackensen, that Poland would be taken and all its garrisons, and the bulk of the Russian military power be destroyed.
The first blow fell at Gorlice in Galicia in the last days of April. Mackensen, furnished with the greatest train of artillery war had ever seen, burst through the Russian lines along the Dunajec, destroyed Dmitrieff's army, which faced him, almost captured the Russian Carpathian forces and drove the Russians rapidly beyond the San, retook first Przemysl and then Lemberg, thus clearing all but a corner of Galicia.
The main German and Austrian armies were then sent north toward Brest-Litovsk, while Hindenburg began his thrust by attacking Ossowetz and the Niemen-Bobr-Narew barrier of forts. By this time the world knew that Russian ammunition had failed and for many weeks the possibility of a tremendous Russian disaster existed. Step by step the Russians were pushed back. The fall of Warsaw was assured in July and it was not until August that the escape of the Russian garrison was certain. The same problem was raised about Kovno and Brest-Litovsk, but again the Russians won clear. Late in August the final net of the Germans about Vilna was drawn, but for the last time the Russians eluded it.
And with the battle of Vilna the German eastern campaign practically ends. In the north the Russians held Riga and the Dwina line, in the center they were behind the great marshes of Pinsk, to the south they were behind the Styr and Stripa, still holding Rowno, still clinging to a corner of Galicia. They had lost hundreds of thousands of prisoners and many guns. All of Russian Poland, most of Courland, and much other territory had been surrendered. But they had kept their armies intact and were once more in line.
In so far as the German campaign had been designed to free Austrian soil and relieve the pressure upon Austrian and German fronts in the east, it had been a shining success. It had served, too, to restore German prestige in the Balkans. But it had come too