Germans Capture Vilnus and Warsaw
On September 19th, the Germans ended their offensive against the Russians by capturing Vilna. Thus, they completed their capture of all of Poland and Lithuania.
The first year of World War I on the Eastern Front had seen first a successful Russian offensive, followed by a very successful counteroffensive by the German in which they regain all of the land originally lost in the Russian offensive.
At the end of 1914 the lines were roughly were they began the war. The Germans were on the Prussian Russian border, and the Russians were manning their fortification that ran all the way from the Baltic to the mountains of Galicia.
The Germans planned a major offensive for 1915 transferring some troops from the static battlefield of west to the east. On May 1, 1915 the German launched a major offensive in the direction of Warsaw. Prior to the attack they had made a small attack in the North against Lithuania successfully drawing Russian troops North. The Germans succeeded in advancing capturing the Russian fortifications at Gorlice Tarnow on June 17th. When the last German fortification fell at Fort Ivang-orod, the Russians had no choice but withdraw from Warsaw, which they did on August 5, 1915.
With their forces advancing rapidly in the center of the front, the Germans resumed their initial offensive in the North. On August 19th after an 11 day battle Kaunus fell to the Germans. On August 25th Brest-Litovsk was captured by German forces. Finally in September 19th Vilnus was captured. By capturing Vilnus the Germans had succeeded in capturing all of the Polish/Lithuanian area that had been occupied by the Russians for 100 years.