Tannenberg, Battle of

Victory of a combined Polish and Lithuanian army over the Knights of the Teutonic Order in 1410, at Tannenberg, a village in northern Poland (now Grunwald). The battle broke the Knights' hold over Old Prussia (approximately modern Poland); their defeat led to the Treaty of Thorn and to an independent Polish state.

The Teutonic Knights were originally formed during the Crusades, and later undertook the conversion and conquest of Old Prussia. Eventually the Teutonic Knights took control of Poland, responsible to nobody other than the Pope, but their rule was oppressive and in 1410 the population, led by King Władysław Jagiełło, Grand Duke of Lithuania and king of Poland, rose against them. Władysław led an army of 20,000 to meet some 15,000 Knights near Tannenberg and completely defeated them, slaughtering several thousand Knights.