The fighting was terribly fierce, and the Germans lost heavily. Around Borzymov the slaughter was so great that the ground was cumbered with German dead, and the survivors used the bodies of their fallen comrades to build up defences. The woods to the south of the Bolimov-Warsaw road were also strewn with dead. By 8th February the Germans had been flung back to the banks of the Rawka, and the Russians had crossed the river at Dachova. The German loss cannot have been less than 20,000 men. The great attempt had failed, and it was now clear that Warsaw could not be captured by a frontal attack.
As soon as von Hindenburg saw that the Bzura-Rawka lines were too strong for him, he was ready with a new plan. He was now about to try a flank attack. Look carefully at the map on the next page and notice the railways which meet in the Polish capital. By these railways alone can a Russian army maintain itself westward of the Vistula. In front of the main railway (A A) from Warsaw to Petrograd you see a river line--that of the Niemen and the Narev. Von Hindenburg's plan was to push out from East Prussia, carry the river line, cut the railway, and thus force the Russians to retire from Warsaw, which would then fall into his hands. Meanwhile the Austrians, on the Russian left wing, were to drive back Brussilov, relieve Przemysl, and try to recapture Lemberg. If these operations should succeed, the Russians would be forced back from the line of the Vistula to the river Bug, and it would take them a year's fighting to recover the lost ground.
First of all we will follow the fortunes of the East Prussian campaign. While the fighting was proceeding on the Rawka, the Russians, who numbered about 120,000, were making headway in East Prussia. Despite the keen frost, the icy winds, and the deep snowdrifts, they pushed back the weak German forces opposed to them, until, on 6th February, their right was not far from Tilsit, and their left rested on the town of Johannisburg. Nowhere were they less than twenty-five miles within the East Prussian frontier.
On 7th February von Hindenburg sprang his surprise upon the invaders. He suddenly hurled 300,000 men against the whole line which the Russians were holding. According to custom, the German left wing made an outflanking movement. It was successful, and the Russians holding this part of the line were forced to retreat along the railway towards Kovno. The 20th Corps just to the south of it now had its right "in the air," and was obliged to retire. In the forests and marshes north of Suwalki it was broken up into parties of stragglers. The remainder of the Russian line was also driven back, but only after a stern struggle. By 15th February the Germans were on Russian soil, and were moving towards the river line which screens the railway from Warsaw to Petrograd. They were about to attack on the Niemen, the Bobr, and the Narev at one and the same time. If the river line should be forced, the railway would soon be reached and cut.