In 1910 General Yuri Danilov of the Russian Army developed what became known as Plan 19. Danilov argued that on the outbreak of war in Europe the German Army would concentrate its forces against France. Danilov therefore suggested that four of its armies (19 corps) should immediately invade East Prussia.
Some leading members of the Russian Army disagreed with the tactics of Plan 19. They argued that Austria-Hungary represented a greater threat to Russia than Germany. In 1912 it was decided to substantially alter Plan 19. Only two armies were now to attack East Prussia with the rest concentrating on defending Russia from the Austro-Hungarian Army.