The Battle of Grunwald in 1410 was one of the most important battles of the Polish-Lithuanian-Teutonic War, and a major victory for the Polish-Lithuanian forces. The battle was fought on July 15th, 1410, near the
From Wikipedia
The Battle of Grunwald, also known as the (First) Battle of Tannenberg or the Battle of Žalgiris, was fought on 15 July 1410 during the Polish–Lithuanian–Teutonic War. The alliance of the Crown of the Kingdom of Poland and the Grand Duchy of Lithuania, led respectively by King Władysław II Jagiełło (Jogaila), and Grand Duke Vytautas, decisively defeated the Teutonic Order, led by Grand Master Ulrich von Jungingen. Most of the Teutonic Order's leadership was killed or taken prisoner.