Battle of Tannenberg

Battle of Tannenberg
	Part of the East Prussian campaign of the ; Eastern Front in World War I
	; Russian prisoners of war after the battle
Date	23–30 August 1914
Location	Tannenberg, East Prussia, German Empire (present-day Poland)53°29′45″N 20°08′4″E / 53.49583°N 20.13444°E
Result	German victory
Belligerents
German Empire	Russian Empire
Commanders and leaders
Paul von Hindenburg; Erich Ludendorff; Max Hoffmann; Hermann von François	Alexander Samsonov †; Yakov Zhilinsky
Units involved
VIII Army	II Army
Strength
150,000; 294 machine guns; 728 guns and howitzers	123,000–180,000; 384 machine guns; 612 guns and howitzers
Casualties and losses
21–30 August:; 13,873+ • 1,726+ killed; • 7,461 wounded; • 4,686 missing; Other estimate:; about 30,000 dead and wounded	70,000–120,219 killed, wounded or captured; See § Casualties

The Battle of Tannenberg, also known as the Second Battle of Tannenberg, was fought between Russia and Germany between 23 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) led to the ousting of the First Army from East Prussia.

The battle is particularly notable for fast rail movements by the German Eighth Army, enabling them to concentrate against each of the two Russian armies in turn, first delaying the First Army and then destroying the Second before once again turning on the First days later. It is also notable for the failure of the Russians to encode their radio messages, broadcasting their daily marching orders in the clear, which allowed the Germans to make their movements with the confidence they would not be flanked.

The almost miraculous outcome brought considerable prestige to General (later Field Marshal) Paul von Hindenburg and his rising staff-officer Erich Ludendorff. Although the battle actually took place near Allenstein (Olsztyn), Hindenburg named it after Tannenberg, 30 km (19 mi) to the west, in order to avenge the Teutonic Knights' defeat at the First Battle of Tannenberg 500 years earlier.