The big stubborn Siberians bore the brunt of the German attack, and made a most determined defence. They were assisted by their old enemies and present friends, the Japanese. Several batteries of heavy guns, served by Japanese gunners who had travelled from the Far East by the Siberian railway, now came into action. Nevertheless, the situation was still full of peril. More reinforcements followed, and soon the Russians were so strongly entrenched as to defy all von Hindenburg's efforts. Many of the newcomers had marched from Galicia amidst terrible weather along the right bank of the Vistula, over roads deep in mud or flooded by swollen streams. We do not know exactly the strength of the relieving army, but a Russian writer tells us that in one day "four columns, each 250,000 strong, crossed the Vistula over sixteen pontoon bridges," and deployed on the left bank ready for an advance. By the evening of Monday, the 19th, the German attack slackened and died away, and "on Tuesday there returned to the city thousands of tired-out, woe-begone Siberian Cossacks and Caucasian cavalrymen--the soldiers who had turned the scale. All Warsaw turned out in the rain to give them cakes and cigarettes, handshakes and cheers." Why had the Germans given up their attempt on Warsaw? The Grand Duke was not content with merely holding Warsaw. While the German guns were hurling their shells at the Russian trenches, General Rennenkampf[159] was making a flank attack on the Germans from the fortress of Novo Georgievsk, lower down on the Vistula. We do not know exactly what happened in this part of the battlefield, but one thing is certain--the German left was attacked with crushing force. It was rolled back from the Vistula, but was still fighting hard; but when Ruzsky, on the 22nd, began to carry all before him south of the Pilitza, it was bound to retreat. Rennenkampf followed it up and retook Lodz, while von Hindenburg sullenly retreated towards his frontier, fighting innumerable rearguard actions by the way. Thousands of his men were sacrificed to prevent stores and guns from falling into the hands of the Russians, and the whole country over which he passed was turned into a desert. In one case the lives of 2,000 men of the rearguard were thrown away in order to save a convoy. The roads which von Hindenburg had made during his advance were blown up; railway lines, stations, bridges, and towers were destroyed, and even the rails were twisted into the shape of corkscrews.