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 assumed the throne.

Albert's widow, Elizabeth of Luxembourg, spurned the outcome and advocated for her infant son, Ladislaus the Posthumous, to rule under the guardianship of Frederick III Habsburg whilst purloining the Holy Crown of Hungary.

With the Turkish grip over the Balkans weakened in the aftermath of the Hungarian–Ottoman War (1437–1442), the papacy and papal legate Julian Cesarini urged Władysław to launch the Crusade of Varna.

After initial successes, the outnumbered Christian forces engaged in a decisive battle at Varna, where Władysław was killed in a heroic cavalry charge against Sultan Murad II.

[7] From a young age, Władysław was surrounded by advisors loyal to Zbigniew Oleśnicki (known in Latin as Sbigneus), a cardinal who acted as royal guardian and aimed at maintaining his influence and high position at court.

[8] Oleśnicki learned of Jogaila's death on 1 June 1434 in Poznań, whilst he was en route to the Council of Basel, but decided to remain in Poland and usurp the role of interrex.

[9] He subsequently convened an assembly in Poznań with the assistance of Chancellor Jan Taszka Koniecpolski, and called for the nobles of Greater Poland to warrant Władysław's right to the crown.

[19] However, a customary feudal homage by the burghers at Kraków Town Hall came into effect because of a disagreement between the bishops and Masovia princes concerning the order of precedence in the royal procession and on sitting arrangements.

[20] Duke Siemowit, who was staying in the capital of Kraków at the time, remained a valid contender for the role of regent or caretaker because of his personal qualities and rank, however, the idea was soon dismissed.

[20] Queen Sophia's attempts to be named regent, in accordance with her late husband's instructions, also failed and the general indecisiveness caused the apex of oligarch influence in medieval Poland.

[24] Władysław faced certain challenges early in his reign, in particular the inherited situation in the Grand Duchy of Lithuania was precarious and the ensuing Lithuanian Civil War (1432–1438) threatened Polish interests there.

The conflict began when Władysław's paternal uncle, Švitrigaila, refused to acknowledge fealty to his brother Jogaila and proclaimed political independence, jeopardising the Polish–Lithuanian union.

[26] However, unrest re-emerged when Sigismund Kęstutaitis was assassinated on 20 March 1440 and Władysław's younger brother, Casimir, was proclaimed Grand Duke by Jonas Goštautas and the Lithuanian Council of Lords on 29 June 1440.

[39] On 3 May 1439, Spytko of Melsztyn formed a small but armed ad hoc confederation in the town of Nowy Korczyn against Oleśnicki's desire to exterminate the Hussites and to challenge his authority over the young king.

[40][41] His corpse pierced with arrows laid bare in the field for three days, however, Władysław personally ordered Spytko's body to be returned to his widow and restored the family's noble status and privileges.

[43] He also dedicated himself to subtler diplomatic measures when addressing the issue of Silesia, a large historical region within the Bohemian Crown, but was unwilling to support the Hussites militarily against Sigismund of Luxembourg and his son-in-law, Albert II of Germany.

[44] The Hungarians soon decried the ceremony as an unlawful farce and utilised a reliquary crown for Władysław's coronation on 17 July 1440 at the Basilica of the Assumption of the Blessed Virgin Mary in Székesfehérvár.

[52] The western and northern parts of the country remained on the side of the queen and opposing magnates, chiefly the Counts of Celje (Cilli), the Garai family and Dénes Szécsi, Archbishop of Esztergom.

[53] In order to assert her claim, Elizabeth had to maintain the wealthy mining counties in what now constitutes Slovakia and hired Hussite mercenaries from Bohemia commanded by John Jiskra.

[54] However, this proved insufficient to fund the war against Władysław; she was then forced to handover her privately owned Austrian estates and the Hungarian County of Sopron to the Habsburgs in late 1440 and early 1441.

[54] This conduct alienated many of the lords that initially supported Elizabeth's cause, including Nicholas of Ilok, Ban of Croatia, who switched sides and allied himself with Władysław and John Hunyadi.

[55] This proved paramount when Ulrich II made an attempt to flee to Bratislava (Pozsony); he was caught by a Polish detachment and subsequently imprisoned at Władysław's behest.

[59] In 1442, Sultan Murad II sent Mezid Bey into Transylvania with a large akinji army, raiding cities, towns and villages from the border to Sibiu (known in German as Hermannstadt and in Hungarian as Nagyszeben).

[69] In August, a Polish assembly at Piotrków implored him to make peace with the Ottomans, dissatisfied with the level of taxes raised for the war and believing that Murad's terms could be lucrative.

[71] However, Władysław abjured his oath and the war continued; on 20 September 1444 the king and Hunyadi crossed the Danube, beginning the army's march to the shores of the Black Sea to make contact with the allied fleet.

[73] It allowed the Turks to focus their attention and resources on advancing into Europe; in late October 1444 he crossed the Bosphorus while the Christian fleet was stalled from adverse winds, and the Venetians did not make an effort to prevent that.

[75][76] Hunyadi is purported to have proposed that the Christian left assists the right flank to move the Turks out of position, and stated that "the son of Osman's army shall be defeated".

[77] One of the crusaders, Andreas de Pallatio, later wrote in his memoirs that Władysław seized the initiative on the Christian right flank and tore into Şehabeddin's ranks like "a new Caesar", pushing the Rumelians up the valley's slope.

[80] Facing desperate circumstances and seeing Hunyadi's struggle against the Rumelian sipahis, Władysław decided to take a chance by directly charging the sultan's camp and his armed retinue with heavy cavalry.

According to another controversial version of the legend, promoted by Manuel da Silva Rosa, Władysław (as Henrique Alemão) was the biological father of Christopher Columbus.