Was the battle at tannenberg a defeat for the Russian army?

Yes, the Battle of Tannenberg, fought from August 26 to August 30, 1914, was a significant defeat for the Russian army during World War I. The German forces, led by Generals Hindenburg and Ludendorff, encircled and decimated the Russian Second Army, resulting in heavy casualties and the capture of tens of thousands of Russian soldiers. This defeat severely undermined Russian morale and military effectiveness in the early stages of the war.