Battle of Tannenberg
The Battle of Tannenberg, also known as the Second Battle of Tannenberg, was fought between Russia and Germany between 26 and 30 August 1914, the first month of World War I. The battle resulted in the almost complete destruction of the Russian Second Army and the suicide of its commanding general, Alexander Samsonov. A series of follow-up battles (First Masurian Lakes) destroyed most of the First Army as well and kept the Russians off balance until the spring of 1915. The battle is particularly notable for fast rail movements by the Germans, enabling them to concentrate against each of the two Russian armies in turn, and also for the failure of the Russians to encode their radio messages. It brought considerable prestige to Field Marshal Paul von Hindenburg and his rising staff-officer Erich Ludendorff, but brought about the failure of the Germans to achieve a quick victory in the war, per the Schlieffen Plan.