The German attack in the north began with good progress against the Russians thanks to a German numerical superiority of 3:1. To the south, however, the Russians outnumbered the Germans, putting up fierce resistance until German support troops arrived. The Russians were pushed back along the entirety of the front, with a counterattack in the north on 9 September providing a small relief against the German advance. Eventually the Russians were overwhelmed, facing the possibility of being encircled again by a rapidly moving German flank. General Rennenkampf ordered a retreat to the Russian border with a sustained rear guard against the Germans buying precious time. False news of a Russian counterattack ultimately saved the remains of the 1st Army as it stalled the German advance. The battle was a resounding victory for General Hindenburg, freeing up troops for the western front and expelling the Russians from East Prussia.
— OR —