Tannenberg, battle of (1410), also known as the battle of Grünwald, the decisive engagement of the ‘Great War’ of 1409-11, in which Polish-Lithuanian-Russian forces defeated the military monastic order of the Teutonic Knights, who ruled the region from their vast, forbidding castle-monastery at Marienburg (Malbork). The Polish King Wladislaw II Jagello led a multinational force of about 30, 000 Poles, Lithuanians, Russians, Czechs, and even Mongols towards Marienburg. On 14 July, moving north-west, they encountered the Grand Master of the Teutonic Order, Ulrich von Jungingen, commanding a slightly smaller force between Grünwald and Tannenberg (Stembark). His knights, with some Swiss and English mercenaries, took up position on a crest. The battle began with a salvo from the Teutonic Order's bombards but, like most artillery of the time, that had little effect in the open field. The Tartar cavalry then attacked the order's right flank, but was driven off. The Lithuanian Prince Vitovt attacked but was repelled and the knights began to pursue. The Russians held the centre, however, and the Poles then attacked, again from the right, this time breaking the knights' formation. All the order's senior officers, including the Grand Master, were killed in a crushing defeat that halted the order's eastward advance permanently. The decisive defeat of the Teutonic Knights also gave encouragement to the Hussites in their struggle against the Holy Roman Empire.
— Christopher Bellamy
