The Battle of Masurian Lakes was a significant military engagement during World War I, occurring from February 7 to February 22, 1915. It involved the forces of the German Empire and the Russian Empire in the Masurian Lakes region of present-day Poland. The battle aimed to push back Russian troops that had invaded East Prussia and to secure German control over the area. The battle followed the earlier Battle of Tannenberg, where the Germans had achieved a decisive victory. In this engagement, the Germans successfully encircled and defeated Russian forces, leading to heavy Russian casualties and a retreat. The outcome solidified German dominance in the Eastern Front during this phase of the war.