Wladyslaw II Jagiello, << vlah DIH slahf yah GYEHL law >> (1351?-1434), united Poland and Lithuania under his rule. He was grand duke of Lithuania from 1377 to 1401 and king of Poland from 1386 to 1434. He founded the Jagiellonian dynasty (family of rulers). Jagiellonian kings ruled Poland for nearly 200 years. Under their leadership, Poland expanded its territory and made important cultural, economic, and political advances.
Grand Duke Jagiello married Poland’s Queen Jadwiga in 1386. At the time of the marriage, Jagiello (Jogaila in Lithuanian) took the Christian name Wladyslaw and led Lithuania in converting to Christianity, the religion of Poland. Through the union, Lithuania and Poland became allies against threatened attacks by the Teutonic Knights, an organization of German crusaders. In July 1410, Polish and Lithuanian forces led by Jagiello and his Lithuanian cousin Vytautus won an important battle against the Teutonic Knights at Grunwald (also called Tannenberg) in what is now northeastern Poland.
