Re-enactment of the Battle of Grunwald (1410) in Northern Poland. Battle of Grunwald also known as the Battle of Tannenberg was one of the most important battles in the history of Medieval Europe. It took place on July 15, 1410, near the town of Grunwald in Northern Poland. In the Battle of Grunwald united army of the Kingdom of Poland and the Grand Duchy of Lithuania defeated totally the knights of the Teutonic Order. As a result the Teutonic Order lost its position in the region forever. Every summer thousands of devotees of military history arrive to the battlefield of Grunwald and try to re-enact an atmosphere of those days.