In the early days of October, by means of the gridiron of railways which Germany has constructed on her eastern border for the express purpose of invading Russia, von Hindenburg massed about a million men all along the frontier from Thorn southwards, and soon they began to move across the rolling ridges and low boggy valleys towards the Vistula. The left (A) advanced towards Warsaw along both banks of the Vistula; the centre (B) pushed eastwards from Kalisz; while the right (C) moved north-eastwards from Silesia. The right consisted of three columns, the most southerly of which was composed of Austrians, who were to push along the Upper Vistula. This Austrian column was to work with the column on its left, and both were to strike at Josefov, which stands between the confluence of the Vistula and the San and the fortress of Ivangorod. A glance at the map below will explain why an attempt was to be made to force the river at this point. There is no railway on the eastern bank of the Vistula between Novo Alexandra and the San. The railway strikes off south-east from Ivangorod, and the nearest point on it to Josefov is Lublin, thirty-three miles away. All the roads in this region are bad, and the forces fighting in it are at a great disadvantage, because they have no railway by which to bring up troops, food, ammunition, and big guns. The Russians defending Josefov had no railway on the eastern side of the river within thirty-three miles, while the Germans had a railhead about ten or twelve miles away on the western side. [Illustration: Von Hindenburg's First Advance on Warsaw.] If von Hindenburg could force the river at Josefov, and cut the railway at Lublin, while his northern columns seized Warsaw, the Russians would be in a bad way. They would have to retreat from the line of the Vistula, and for months to come would be unable to take the offensive in Poland. The German plan was excellent if only it could have been carried out secretly. The Russian cavalry, however, soon let the Grand Duke Nicholas know that the German columns were advancing, and he was clever enough to guess exactly what von Hindenburg was trying to do. He knew that if his armies remained to the west of the Vistula they would be badly supplied with food and munitions, because the railways of the Polish plain are few and far between, and also because his forces might easily be divided by the German centre, one column of which was pushing along the north bank of the broad, muddy river Pilitza. He determined to risk nothing, and leaving a screen of light horse west of the river to keep in touch with the enemy, ordered the rest of his forces to fall back behind the San and the Vistula. The march on Cracow had, therefore, to be abandoned; the grip on Przemysl to be loosened; and the Russian army in Galicia brought back for fifty miles, as you have already heard.