Russian invasion of East Prussia (1914)

East Prussian campaign
Part of the Eastern Front of World War I

Eastern Front, 17–23 August 1914.
Date17 August – 14 September 1914
Location
Result
  • German victory
Territorial
changes
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
Strength
Initial: 209,000 men
1,044 guns
Initial: 1st Army: 181,745 and 702 guns
2nd army: 99,594 men and 402 guns
Total: 250,000–431,306 men and 1,100 guns
Casualties and losses

Nelipovich estimate:
13,206 KIA,
26,722 WIA,
2,702 MIA
Total 42,630
Lost:
17 guns
17 machine guns
3 airplanes


Other estimates: Stallupönen – 1,300; Gumbinnen – 14,600; Tannenberg – 12,000; Masurian lakes – 10,000 or 40,000
Total:
37,000–100,000
Tanneberg: 90,000
Masurian Lakes: 100,000
Gumbinnen: 18,000
Stalluppen: 6,000
Total:
160,000–240,000 casualties
100,000+ taken prisoner

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 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 plan of war. The Germans also seemed to have weak cooperation among the troops and disagreements in the generals. The victory in East Prussia inspired too much self-confidence, which led to defeats at Warsaw and Lodz.

The shock of the invasion served to assist the German war effort. According to Alexander Watson "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".