Battle of Tannenberg
The Battle of Tannenberg September 26-30, 1914, actually took place near Olsztyn and it resulted in the nearly complete destruction of the Russian Second Army and the end to any Russian offensive activity.
The German army proved their superior training and ability to maneuver as they totally defeated the Russian at the Battle of Tannenberg. The Germans attacked the Russian flanks and were able to turn the flanks, thus capturing large number of Russian soldiers. The German had intercepted Russian radio signal, all of which were being sent unencoded. The victory was so complete that Russian General Alexander Samsonov committed suicide. The German Germany Field Marshal Paul von Hidenburg was the hero of the battle.