It is said that one day in June, just before the fall of Lemberg, the Kaiser met von Hindenburg and his Chief of Staff, von Falkenhayn, in the castle at Posen. The Kaiser was in high spirits, and he declared that the moment had now arrived for the capture of Warsaw. He already saw himself riding into the city at the head of his troops as the conqueror and deliverer of Poland. The two generals gladly agreed with his proposal. They believed that the Western front could be held without much effort, and that with the mighty engine of artillery which they now possessed they could batter through the Russian lines, and seize the great city which had so long defied them.
After the fall of Lemberg, Warsaw formed the apex of a great salient. It could only hold out so long as the two great railway lines which meet in the city were in the hands of the Russians. The first of these routes runs north-east through Grodno, Vilna, and Dvinsk to Petrograd. The other line runs south-east through Ivangorod, Lublin, Cholm, and Rovno to Kiev.[54] Von Mackensen was already pushing northwards towards this southern line of railway, and the Russians were falling back before him. It was now the business of von Hindenburg to advance from East Prussia and capture the northern line. Once the railways were cut, Warsaw would fall. Von Falkenhayn, however, hoped to do more than merely capture the city and a few more thousand square miles of Polish ground. He hoped to make an end of the Russian armies in the salient, and this he proposed to do by carrying out a great enveloping movement. While von Mackensen was pushing on towards the southern railway, he would make a fierce thrust at the northern part of the same salient, in order to cut the Petrograd line between Warsaw and Bialystok. But this was not the whole of the plan. A German army under von Buelow had already overrun Courland,[55] and was not far from Riga. While the two thrusts were being made at the salient, this force was to hack its way south, seize Kovno and Vilna, and cut the Petrograd line far to the eastward. The Russians in the salient would thus be taken in flank and in rear; they would be squeezed between the enemy on the north and the south, and probably would be surrounded and forced to surrender. Russia would thus be crippled for many a month to come, and then the might of Germany could be flung against the Western front.