We will now follow the fortunes of the three great thrusts that were about to be made--the thrust against the southern railway, the thrust against the Petrograd railway between Warsaw and Grodno, and the thrust against the same railway still farther east. Before the end of June five German armies, with von Mackensen in the centre, were moving steadily northwards to cut the southern railway line between Lublin and Kovel. They had now left the railways of Galicia behind them, and were crossing a country of forests, marshy plains, and bad roads. The great guns moved slowly, but the armies met with little opposition, and by 2nd July they were less than thirty miles from the railway. Round about Krasnik they came into touch with the Russians, who held a strong position, with marshes and streams on their flanks. The army of the Archduke Joseph, to the left of von Mackensen, was heavily assailed, and during four days of attack and counter-attack was driven back with the loss of 15,000 prisoners, a very large number of machine guns, and heavy casualties in dead and wounded. For a week the German advance was checked. It began again on 16th July, when von Mackensen, who had bridged the marshy streams, was able to get his big guns working. Once more he blasted his way through, and on the 18th was within ten miles of the railway. Now let us see what was going on in the north. On 14th July von Buelow's army in Courland began to push forward, and at the same time another army attacked the Niemen front. The great thrust against the Warsaw salient was entrusted to von Gallwitz, who now advanced against the line of the Narev. He made good progress, and the Russians fell back, fighting stubbornly. They retired across the Narev on the 20th, and three days later von Gallwitz won several crossings of the river. By means of one of these crossings he pushed forward until by 25th July, though the river line had not yet been won on a broad front, he lay within twenty miles of the Warsaw-Petrograd railway. Meanwhile the German heavy guns were battering down the outworks of the river fortresses, and the army of the Niemen was within sixty miles of Vilna.