No longer did they talk of a mere defense in the east; an advance on Warsaw was demanded and von Hindenburg was acclaimed the greatest soldier of his day. The Emperor made him Field Marshal, and placed him in command of the Teutonic armies in the east. But von Hindenburg was not satisfied. The remnant of the defeated army had fled toward Narev, and without losing a moment von Hindenburg set off in pursuit. Rennenkampf, all this time, strange to say, had made no move, and at the news of Samsonov’s disaster he abandoned the siege of Koenigsberg and retreated toward the Niemen. At Gumbinnen he fought a rear-guard action with the German left, but had made up his mind that the Niemen must be the Russian line of defense. Von Hindenburg, following, crossed the Russian frontier and in the wide forests near Augustovo there was much fighting. This action, described as the first battle of Augustovo, was only a rear-guard action, the Russians desiring merely to delay the enemy for a day or two. German reports, however, described it as a victory only second in importance to Tannenberg. Von Hindenburg then occupied Suwalki. He apparently had become over confident, and hardly realized that Rennenkampf was continually being reinforced by the Russian mobilization. The Russian High Command understood the situation very well. Their aim was to keep von Hindenburg busy on the Niemen, while their armies in the south were overwhelming the fleeing Austrians. Von Hindenburg was deceived, and continued his advance until he got into serious trouble. His movement had begun on September 7th; his army consisted of the four corps with which he had won Tannenberg, and large reinforcements from Germany, including at least one guards battalion, and a number of Saxons and Bavarians. The country is one vast mixture of marsh and lake and bog. The roads are few, and advance must therefore be slow and difficult. Rennenkampf made no attempt to delay him beyond a little rear-guard fighting. The German army reached the Niemen on September 21st, and found behind it the Russian army in prepared positions, with large reinforcements from Vilna. The river at this point was wide and deep, and hard to cross. The battle of the Niemen Crossings was an artillery duel. The Russians quietly waited in their trenches to watch the Germans build their pontoon bridges. Then their guns blew the bridges to pieces. Thereupon von Hindenburg bombarded the Russian lines hoping to destroy the Russian guns. On Friday, the 26th, his guns boomed all day; the Russians made no reply. So on the morning of the 27th he built bridges again, and again the Russians blew them to pieces. Moreover the marshy ground made maneuvering almost impossible. On the 28th he gave the order for retreat.