Battle of Tannenberg - Background

Background

The Allied battle plan prior to the war had been based on France and the United Kingdom halting the German armies in the West while the huge Russian armies could be organized and brought to the Eastern front. The numbers were overwhelming; in perhaps as little as a month, the Russians could field around ten complete armies, more men than the Germans could muster on both fronts put together. However, at Tannenberg the actual ratio of Russian to German troops was closer to 16 to 29.

Frustrating this plan was the Russians' lack of a good quality railroad network. Additionally, Russian trains operated on a different rail gauge than Germany, meaning that unless the Russians acquired German railroad engines and cars, their armies could only be transported by rail as far as the German border. The presence of the armies of Austria-Hungary to the south as well as initially those of Japan to the east limited Russia's involvement in the beginning (however, Japan declared war on Germany on 23 August 1914). Nevertheless, the Russians considered the Germans to be their primary threat, and planned to use limited forces to quickly seize East Prussia.

The Germans likewise considered the Russians to be their primary threat. The entire Schlieffen Plan was based on the idea of defeating France as quickly as possible, and then transporting their armies by train to the eastern front. This allowed the Germans to garrison Prussia fairly lightly with a single army, the Eighth, while the German Ninth Army was stationed in central Germany to reinforce either front. There was little allowance for anything other than a delaying action while the outcome in the west was decided. In order to delay the Russian forces as long as possible, the entire area around Königsberg, near the Russian border, was heavily fortified with a long series of fieldworks.

Just prior to the opening of the war the situation developed largely as prewar planning had expected. The German Eighth Army was in place southwest of Königsberg, while the two available Russian armies were located to the east (First Army) and south (Second Army), the latter in what was known as the "Polish Salient". Russian battle plans called for an immediate advance westward by the Russian First Army under General Pavel von Rennenkampf into East Prussia, with Königsberg as the initial objective. The Russian Second Army under General Alexander Samsonov was to initially move westward around the Masurian Lakes and then swing north over a hilly area to cut off the Germans, who would by this point be forced into defending the area around Königsberg. If executed successfully, the Germans would be surrounded.