By the beginning of the third week in August the first Russian armies were ready. Her forces were arranged as follows: Facing East Prussia was the Army of the Niemen, four corps strong; the Army of Poland, consisting of fifteen army corps, occupied a wide front from Narev on the north to the Bug Valley; a third army, the Army of Galicia, directed its line of advance southward into the country between Lemberg and the River Sareth. The fortresses protecting Warsaw, still further to the east, were well garrisoned, and in front of them to the west were troops intended to delay any German advance from Posen. The Russian commander-in-chief was the Grand Duke Nicholas, uncle of the late Czar, and one of the most admirable representatives of the Russian at his best; a splendid soldier, honest, straightforward, and patriotic, he was the idol of his men. He had with him a brilliant staff, but the strength of his army lay in its experience. They had learned war in the bitter school of the Manchurian campaign. The German force on the frontier was not less than five hundred thousand men, and they were arranged for defense. Austria, in Galicia, had gathered nearly one million men under the auspices of Frederick. The first movement of these armies took place in East Prussia. The Army of the Niemen had completed its mobilization early in August, and was under the command of General Rennenkampf, one of the Russian leaders in Manchuria. In command of the German forces was General von François, an officer of Huguenot descent. The first clash of these armies took place on the German frontier near Libau, on August 3d. Two days later, the Russians crossed the frontier, drove in the German advance posts, and seized the railway which runs south and east of the Masurian Lakes. The German force fell back, burning villages and destroying roads, according to their usual plan. On the 7th of August the main army of Rennenkampf crossed the border at Suwalki, advancing in two main bodies: the Army of the Niemen moving north from Suwalki, the Army of the Narev marching through the region of the Masurian lakes. In the lake district they advanced toward Boyen, and then directed their march toward Insterburg, the most important town in the neighborhood. To protect Insterburg, General von François made his first stand at Gumbinnen, where, on the 16th of August, the first important battle of this campaign took place. The result was the defeat and retirement of the Germans, and von François was forced to fall back on Koenigsberg.