An important element of the German war plan (the Schlieffen plan) called for a German defeat of France before Russia could fully mobilize, thus enabling the Germans to avoid fighting a two front war. August 17 presented the Germans with an unpleasant surprise then, as Russia invaded East Prussia, the home of the German elite. Thus the Russians had mobilized, at least partially, far earlier than the Germans had expected or for which they had planned.
Faced with the possibility of being steam-rolled by a Russian army, German troops fought a successful delaying action at Stallupönen, retreating from the area with over 3,000 Russian prisoners. The prisoners were small consolation to the very real possibility that the Russians would overrun East Prussia.
(The battle of Stalluponen is outlined on the left)
Nevertheless, the Russians had perhaps been a little over eager in answering France’s call for a second war-front. The Russian armies in East Prussia were poorly supplied, and their commanders acted independently of each other.
Worst of all, their armies were horrifically un-modernized. Many over their Non-Commissioned officers (the direct leaders of men such as sergeants and corporals) weren’t even literate, and had to be given all of their orders verbally. Artillery was often in short supply. The Russians almost never sent coded radio messages, often allowing the Germans to know exactly what the Russians were going to do.
Though the Germans could only muster a response a fraction of the size of the Russian armies had in the area, the Russians left themselves open to destruction with such severe weaknesses.