Władysław III of Poland

Władysław III of Poland (31 October 1424 – presumably 10 November 1444), also known as Ladislaus of Varna, was King of Poland and Supreme Duke of the Grand Duchy of Lithuania from 1434, as well as King of Hungary and Croatia as Vladislaus I from 1440 until his presumed death at the Battle of Varna. He was the eldest son of Władysław II Jagiełło (Jogaila) by his fourth wife, Lithuanian noblewoman Sophia of Halshany.

Władysław III succeeded his father shortly before turning ten in 1434 and was, therefore, deemed unfit to rule until coming of age. Cardinal Zbigniew Oleśnicki acted as regent and a temporary provisores council executed power in the king's name. However, Władysław III's legitimacy to the crown was contested by Lesser Polish nobles favouring the candidacy of Siemowit V of Masovia, who was of Piast lineage. In the aftermath of the coronation, Spytko III of Melsztyn accused Oleśnicki, the council and the Catholic Church of exploiting the king's youth to hold authority. A sympathiser with the Czech Hussites, Spytko was killed at the Battle of Grotniki in 1439, thus ending the hostilities.

Władysław III simultaneously faced the effects of the Polish–Teutonic War, which commenced under his father's reign in 1431. The Teutonic Knights began supporting Švitrigaila and the Livonian Order in a military struggle against Poland and Sigismund Kęstutaitis of Lithuania in 1434, shortly after Władysław III assumed the throne. Consequently, the king and the Polish Royal Council, the curia regis, renewed their war efforts by fortifying the borderland regions and sending an army to Lithuania, which was engulfed in a civil war since 1432. Švitrigaila, the Livonians and their allies were ultimately defeated at the Battle of Wiłkomierz, and Władysław forced the Peace of Brześć Kujawski on the Teutonic State in December 1435, which curtailed Teutonic influence in East-Central Europe.