The Battle of Tannenberg

The Battle of Tannenberg was an engagement between the Russian Empire and the German Empire in the first days of World War I. 

It was fought by the Russian Second Army against the German Eighth Army between 26 August and 30 August 1914. The battle resulted in the almost complete destruction of the Russian Second Army. A series of follow-up battles destroyed the majority of the First Army as well, and kept the Russians off balance until the spring of 1915.

The battle is notable particularly for a number of rapid movements of complete German corps by train,allowing a single German army to concentrate forces against each Russian army in turn.

Although the battle actually took place close to Allenstein (Olsztyn),General Erich Ludendorff's aide, Colonel Max Hoffmann, suggested naming it after Tannenberg, in the interest of Pan German ideology,to counter the defeat of the Teutonic Knights at the Battle of Grunwald (Tannenberg) in 1410 by the Poles, Lithuanians and Russians.

 As pointed out by Christopher Clark, the actual Tannenberg is some 30 km (19 mi) to the west, and there was no intrinsic reason—other than the historical battle and its emotive resonance in the narrative of German and Slavic nationalism—to give its name to the 1914 battle.