On July 15, 1410, the famous Battle of Greenwald broke out. 39,000 of the Polish-Lithuanian army, under the command of King Vladislav Jagiello of Poland, engaged in a decisive battle with the army of about 27,000 of the Teutonic Knights near Tannenberg and Greenwald. The Teutonic Knights lost all their elites in the battle, 8,000 knights were killed, 2,000 were captured, and most of their leaders, such as Grand Master von Junggingen, were killed. The Teutonic Knights were devastated from then on, and Poland gradually regained lost territory, gaining towns such as Gdansk and access to the Baltic Sea. (Polish author Henckiewicz wrote the novel "Crusader Knights" based on this battle)

Comments: The Teutonic Knights began to decline since then, but this organization has continued to exist today