Russian invasion of East Prussia (1914)
|East Prussian Campaign|
|Part of the Eastern Front during World War I|
Eastern Front, 17–23 August 1914.
|Russian Empire||German Empire|
|Commanders and leaders|
| Paul von Rennenkampf
Alexander Samsonov †
| Paul von Hindenburg
Maximilian von Prittwitz
II Army X Army Total more than 800,000 men
|VIII Army Total 250,000 men|
|Casualties and losses|
|in 4 main battles more than 320,000 men (Stallupönen - 7,500; Gumbinnen - 19,000; Tannenberg - 170,000; Masurian lakes - 125,000) Another estimate: more than 300,000 ||Total about 37,000 men (Stallupönen - 1,300; Gumbinnen -14,600; Tannenberg - 12,000; Masurian lakes - 10,000)|
The Russian invasion of East Prussia occurred during the First World War, lasting from August to September 1914. As well as being the natural course for the Russians to take upon the declaration of war with Germany, it was also an attempt to focus German military eyes on the Eastern Front, as opposed to the Western Front, where France was increasingly under the strain of her own German invasion. Despite more than threefold numerical superiority (250,000 Germans against 800,000 Russians) invasion ended with a crushing defeat of the Russian army, Russian losses were 9 times larger than the German.
The Germans initially planned to have only the 8th army to act, as they expected that the Russians would be slow to mobilise, leaving Germany to beat France in a few weeks thereby allowing the victorious, battle-hardened German troops to transfer along Germany's superior transport network to fight the Russians on the Eastern Front. This was the basis of the Schlieffen Plan.
However, quite quickly, Russia was able to mobilize an invasion into East Prussia. Any invasion of Prussia was an important blow to German morale as well as her general strategic situation, due to Prussia (including East Prussia) being the historical heart of the German Reich (Empire). The German deployment on the outbreak of the war left only the 10 divisions of the German Eighth Army under General Maximilian von Prittwitz in East Prussia whereas the Russians had been able to mobilize the First Army, under General Paul von Rennenkampf and the Second Army, under General Alexander Samsonov. They entered East Prussia on 7–9 August.
The Battle of Stallupönen, fought between Russian and German armies on 17 August 1914, was the opening battle of World War I on the Eastern Front. It was a minor German success, but did little to upset the Russian timetables.
The Battle of Gumbinnen, started by the Germans on 20 August 1914 was the first major offensive on the Eastern Front during the First World War. Due to the hastiness of the German attack the Russian army emerged victorious. The Germans were forced to retreat, perhaps with the intention of performing holding actions in Mazuria, or even retreating to the River Vistula which would have meant abandoning the salient of East Prussia. This would have fitted in with the plans made before the start of the First World War; that these were the positions the Germans would retreat to if the Russians put up a much stronger fight than they had anticipated. Regardless of whatever preparations had been made, however, it still remained that the Germans could not let the Prussian capital, Königsberg fall into Russian hands. The moral, symbolic and military value (since it was a major military hub) of the city meant to lose it was to invite disaster on the home front, in addition to the strategic ramifications. Also, it was very likely that the Russians would have used the upper hand thus gained to use their superior forces to overwhelm the static German defenses. In short, the Germans had to fight back immediately and force the Russians from East Prussia.
Helmuth von Moltke the Younger, Chief of the German General Staff from 1906 to 1914 replaced Prittwitz with Paul von Hindenburg (brought out of retirement) on 22 August. Hindenburg, along with his Chief of Staff, the formidable Ludendorff would approach the crisis in East Prussia very differently from Prittwitz, who panicked when the Russian onslaught entered East Prussia. In contrast to Prittwitz, Hindenburg and Ludendorff decided to take the offensive and encircle one of the opposing armies. Following the plans of Colonel Max Hoffmann, Prittwitz's deputy chief of operations, they chose to send eight divisions against Samsonov in the Battle of Tannenberg resulting in over 90,000 captured and 70,000 killed or wounded. The Second Army was destroyed and Samsonov shot himself.
In the Battle of the Masurian Lakes, the Germans forced the First Army to retreat out of East Prussia.
The invasion was a ghastly failure for the Russians, a setback which was followed by considerable German advances in the following year, including the capture of the Polish city of Warsaw. However, the crisis caused in the German High Command by the unexpected Russian advance forced the sending of 2 corps and a cavalry division from the Western Front as part of the new 9th Army in order to support the attack on the Russians. These additional forces did not arrive in time for the twin battles, as Ludendorff predicted and, had they entered France as originally planned could have been tremendously helpful to the precarious situation in the West. In the Head of French Intelligence Colonel Dupont's words, "their debacle was one of the elements of our victory."
Comparison of forces
The Russians originally had only two armies (1st and 2nd, 19 infantry and 8 cavalry divisions - 400,000 soldiers plus 30,000 sabers, totalling 430,000 men) against the German VIII Army (9 infantry and 1 cavalry divisions- 145,000 soldiers plus 4,000 sabers; totaling less than 150,000 men).  
Due to an inferior rail system and the subsequent changing of cars on a different gauge of rail in Germany, Russian mobilization was sluggish, but had gradually built up a considerable surplus of manpower. By the early part of September, the Russians had built up a considerable reserve from the influx of new divisions and corps arriving by rail.
At the same time, the German army had received from the Western Front only two weakened army corps (4 infantry divisions) and 1 cavalry division. Therefore, even with reinforcements and supporting units Germans had no more than 250,000 soldiers.
Despite the complete destruction of the Second Army, before the First Battle of the Masurian Lakes in September, against the Eighth German Army, the Russians had a minimum of 428 infantry battalions. This is equivalent to 27 infantry divisions - more than 560,000 troops, plus more than 250 squadrons of cavalry,; a large number of supporting units - generally much more than 600,000 men; and this despite the losses of 200,000 soldiers in battles of Stallupönen, Gumbinnen and Tannenberg. Therefore, the minimum number of Russian troops against the German VIII Army was at least 800,000 soldiers.
- Robert B. Asprey, L'Alto comando tedesco, Milano, Rizzoli, (1993), p. 39 (English edition: Robert B. Asprey,The German High Command at War: Hindenburg and Ludendorff Conduct World War I, 1993)
- R.Asprey, L'Alto comando tedesco, p. 84.
- including 150,000 prisoners
- Tannenberg 1914, Warszawa, 2005; p. 18.
- Tannenberg 1914, 2005; p. 29
- Hastings, Max. Catastrophe: Europe goes to war 1914 London: William Collins, 2013; p. 281
- David Eggenberger, An Encyclopedia of Battles: Accounts of Over 1,560 Battles, 2012, p. 270
- R. Kent Rasmussen, World War I for Kids: A History with 21 Activities, 2014, p. 43
- Der Weltkrieg 1914 – 1918. Вand 2. S. 317, 346
- Tannenberg 1914, 2005, p. 18.
- Tannenberg 1914, 2005; p. 32
- Hastings, Max., 2013; p. 281
- David Eggenberger, 2012, p. 270
- another estimate: 135,000 Germans versus 650,000 Russians. See Roger Chickering, Imperial Germany and the Great War, 1914-1918, 2004, p. 24
- Gilbert, Martin (1994). The First World War: A Complete History. New York: Henry Holt and Company. ISBN 080501540X.
- Jukes, Geoffrey, ed. (2002). The First World War: The Eastern Front, 1914-1918. Oxford: Osprey Publishing. p. 22. ISBN 184176342X. Retrieved 2014-02-17.
- Simkins, Peter; Jukes, Geoffrey; Hickey, Michael, eds. (2003). The First World War: The War to End All Wars. Oxford: Osprey Publishing. p. 198. ISBN 1841767387. Retrieved 2014-02-17.
- Tuchman, Barbara W. (2009-07-22). The Guns of August: The Outbreak of World War I. Presidio Press. p. 520. ISBN 0345476093. Retrieved 2014-02-17.
- excluding supporting units
- excluding supporting units
- Each Russian division had 21,000 men; in contrast a German division had only 16,000
- details about the correlation of forces see in the book B. Zawadzki: Kampania jesienna w Prusach Wschodnich, Wojskowy Instytut Wydawniczy, Warszawa 1924, p. 299
- B. Zawadzki, 1924, p. 299
- Florinsky, Michael T. "The Russian Mobilization of 1914," Political Science Quarterly (1927) 42#2 pp. 203–227 in JSTOR
- B. Zawadzki. "Kampania jesienna w Prusach Wschodnich", Wojskowy Instytut Wydawniczy, Warszawa 1924
- The Eastern Front, Osprey Publishing.