Władysław II Jagiełło

Jogaila (Lithuanian: [jɔˈɡâːɪɫɐ] ^ⓘ; c. 1352/1362 – 1 June 1434), later Władysław II Jagiełło (Polish: [vwaˈdɨswaf jaˈɡʲɛwwɔ] ^ⓘ), was Grand Duke of Lithuania beginning in 1377 and starting in 1386, becoming King of Poland as well. As Grand Duke, he ruled Lithuania from 1377 to 1381 and from 1382 to 1401, at which time he became the Supreme Duke of Lithuania in exchange for naming his cousin Vytautas as the new Grand Duke. Władysław II initially served as King of Poland alongside his wife Jadwiga until her death in 1399, and then the sole ruler until his own death in 1434.

Raised a Lithuanian polytheist, he converted to Catholicism in 1386 and baptized as Ladislaus (Polish: Władysław) in Kraków, married the young Queen Jadwiga, and was crowned King of Poland as Władysław II Jagiełło. In 1387, he converted Lithuania to Catholicism. His reign in Poland started in 1399, upon the death of Queen Jadwiga, lasted a further thirty-five years, and laid the foundation for the centuries-long Polish–Lithuanian union. He was a member of the Jagiellonian dynasty in Poland that bears his name and was previously also known as the Gediminid dynasty in the Grand Duchy of Lithuania. The dynasty ruled both states until 1572, and became one of the most influential dynasties in late medieval and early modern Europe.

Jogaila was the last pagan ruler of medieval Lithuania. After he became King of Poland, as a result of the Union of Krewo, the newly formed Polish-Lithuanian union confronted the growing power of the Teutonic Order. The allied victory at the Battle of Grunwald in 1410, followed by the Peace of Thorn, secured the Polish and Lithuanian borders and marked the emergence of the Polish–Lithuanian alliance as a significant force in Europe. The reign of Władysław II Jagiełło extended Polish frontiers and is often considered the beginning of Poland's Golden Age.