While battles raged in Western Europe the Russian army was advancing into East Prussia, the heartland of the German army. Most of the German army was in the West and they were put in a situation where they were drastically outnumbered. How then, did the German army manage to inflict one of the most crushing defeats of the war on the Russian army? In the south the Austrians move over to the attack, running smack into the Russians in Galicia. It doesn't go so well for them.
The History of the Great war is now available on Stitcher
Opening moves in Prussia courtesy of westpoint.edu
Battle of Tannenberg courtesy of westpoint.edu
Movements before Tannenberg
Battle of Galicia