Russian invasion of East Prussia (1914)

East Prussian campaign
Part of the Eastern Front of World War I
Eastern Front, 17–23 August 1914.
Date 17 August – 14 September 1914 Location East Prussia, German Empire Result German victory German forces invade Poland Territorial changes Germany recaptures all of East Prussia. Germany captures land in Poland.
Belligerents
German Empire	Russian Empire
Commanders and leaders
Paul von Hindenburg Erich Ludendorff Max Hoffmann Maximilian von Prittwitz	Nicholas Nikolaevich Yakov Zhilinsky Paul von Rennenkampf Alexander Samsonov † Vasily Flug
Units involved
VIII Army	I Army II Army X Army
Strength
Initial (including reserves): 209,522 men[1] Later from Western Front:[2] 46,866[3] men Total: 256,388 men	Initial (including reserves): 1st Army: 222,053[4] men 2nd Army: 280,902[5] men Later: 10th Army: 247,467[6] men Total: 750,422 men
Casualties and losses
official German medical reports: 13,206 KIA, 26,722 WIA, 2,702 MIA Total 42,630[7] Lost:[8] 17 guns 17 machine guns 3 airplanes Other estimates: Stallupönen – 1,300;[9] Gumbinnen – 14,600;[10] Tannenberg – 12,000;[11] Masurian lakes – 10,000[12] or 40,000[13][14][15] Total: 37,000[16]–100,000[17]	official Russian medical reports: 24,589 KIA, 48,204 WIA, 167,533 MIA Total 240,326[18] Lost:[19] 462 guns 352 machine guns 10 airplanes Other estimates: 160,000-180,000 total Tanneberg: 70,000[Note 1][20] Masurian Lakes: 60,000[21][22][Note 2] Gumbinnen: 18,000 Stalluppen:6,000[23] Total: 160,000–320,000 60,000-100,000 taken prisoner[17][20]

The Russian invasion of East Prussia occurred during World War I, lasting from August to September 1914. As well as being the natural course for the Russian Empire to take upon the declaration of war on the German Empire, it was also an attempt to focus the Imperial German Army on the Eastern Front, as opposed to the Western Front. Despite having an overwhelming superiority over the Germans in numbers, the invading Imperial Russian Army spread its forces thin and was defeated in the battles of Tannenberg and the Masurian Lakes, resulting in a complete strategic collapse of the Russian invasion.

The shock of the invasion served to assist the German war effort according to one historian, who argued that "Outrage at the violation of national territory and Tsarist atrocities strengthened German solidarity, cemented conviction in the righteousness of the national cause, and acted as a terrible and lasting warning of the penalties of defeat".^[24]

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