With regard to a possible future two-front war, Alfred von Schlieffen, the Chief of the General Staff from 1891–1906, had suggested a deployment scheme which became known as the Schlieffen Plan. Modified by Moltke the Younger, its intention of quickly defeating France proved impossible to achieve. In the actual event of the first world war; on the Western Front, the German advance stalled into trench warfare after the First Battle of the Marne. On the Eastern Front, however, the Prussian operations succeeded in encircling and smashing the Russians at Tannenberg. Though developing infiltration tactics as a way of re-introducing maneuver to modern warfare, they were unable to achieve a decisive breakthrough in their Spring Offensive on the Western Front in the last year of the war, and the Germans lost the war of attrition.