However, as a representative of the interests of the Austrian and Hungarian estates, he could not defend himself against his rival, Frederick III, King of the Romans, who in turn took over his role as guardian of Ladislaus.

Albert had to renounce his guardianship and in return received the mighty Hungarian border castle Forchtenstein, including a principality in the Hungarian-Styrian-Carinthian area.

[1] Ladislaus lived at Frederick's court (mainly in Wiener Neustadt), where Aeneas Silvius Piccolomini (later Pope Pius II) wrote a treatise on his upbringing.

[5][7] In Bohemia, Albert was unanimously elected king only after he defeated Casimir – the younger brother of Vladislaus III of Poland – who was supported by a group of Hussite lords and burghers.

[8] Albert was planning to launch a military expedition against the Ottoman Turks, who had been making plundering raids in the southern regions of Hungary, but fell seriously ill during the preparations.

[9][10] Fearing a new Ottoman invasion of Hungary, the majority of the Hungarian lords and prelates refused to accept the deceased king's last will.

[11][12] In Bohemia, the assembly of the Estates passed decrees in January 1440 to avoid having a new civil war break out between the Hussites and the Catholics before a new king was elected.

[10][18] In Bohemia, only the Catholic lords, who were under the leadership of Ulrich II of Rosenberg,[13] were willing to accept Ladislaus' hereditary right to rule.

[20] After a young lord, Nicholas Újlaki, symbolically knighted the infant Ladislaus, Archbishop Dénes Szécsi anointed and crowned him king on 15 May.

[20] During the lengthy ceremonies, his mother's cousin, Ulrich II, Count of Celje, held the crown over the head of Ladislaus who burst into tears while the coronation oath was being read out on his behalf.

[11][19] In need of financial resources to continue the war against Vladislaus, Queen Elizabeth signed a treaty with Frederick III, King of the Romans, in Wiener Neustadt on 22 November.

[3] Queen Elizabeth hired a Czech condottiere, John Jiskra of Brandýs, who took control of Kassa (now Košice in Slovakia) and a dozen other towns in Upper Hungary during the next months.

[25][27] However, Vladislaus' two military commanders, Nicholas Újlaki and John Hunyadi, defeated the united army of the child Ladislaus's supporters from the central and southern parts of Hungary in the Battle of Bátaszék in early 1441.

[18][30][32] After the death of Ladislaus' mother, his claim to rule in Hungary and Bohemia was primarily protected by Jan Jiskra and Ulrich of Rosenberg, respectively.

[18] In Bohemia, the moderate Hussite lord, Hynce Ptáček of Pirkstein, administered the eastern territories, and the towns dominated by the radical Taborites were united in a league.

[13] The Hussite Ctibor Tovačovský of Cimburk, who had assumed the title governor after Albert's death, continued to administer Moravia, closely cooperating with the towns and the Catholic Bishop of Olomouc.

[6] Frederick III authorized the Estates of Luxemburg to pay homage to Philip the Good, but he also stipulated that Ladislaus could buy back the duchy after Elizabeth of Goerlitz's death.

[34][35] At the Diet of next year, the Hungarian Estates agreed that they would acknowledge the child Ladislaus as king if Vladislaus, whose fate was still uncertain, did not come back to Hungary before 1 June 1445.

[37] The Estates also elected seven "Captains in Chief" – John Hunyadi, Nicholas Újlaki, George Rozgonyi, Emeric Bebek, Michael Ország, Pancrace Szentmiklósi, and Jan Jiskra – to administer the kingdom.

[3] Aeneas Silvius Piccolomini (the future Pope Pius II) summarized his advice on education in a letter that he addressed to the ten-year-old Ladislaus in 1450.

The aim of eating is to strengthen the frame; so let vigorous health reject cakes or sweets, elaborate dishes of small birds or eels, which are for the delicate and the weakly.

A boy should be brought up to avoid wine; for he possesses a store of natural moisture in the blood and so rarely experiences thirst.John Hunyadi signed a peace treaty with Frederick III on 22 October 1450.

[44] After their return from Italy, Emperor Frederick again refused to renounce the guardianship of Ladislaus, provoking the Austrian Estates to rise up in open rebellion in early 1452.

[44] The representatives of the Austrian and Hungarian Estates, and the Bohemian Catholic lords, signed a treaty in Vienna on 5 March against Emperor Frederick, but he refused to hand over Ladislaus to them.

[13] The rebellious Austrian lords laid siege to Wiener Neustadt, forcing Emperor Frederick III to hand over Ladislaus to Ulrich of Celje on 4 September.

[50][53] Ulrich of Celje also signed a treaty with Archbishop Dénes Szécsi, Ladislaus Garai, Nicholas Újlaki, and other Hungarian lords on 13 September, who promised to support him against his opponents.

[58] Historian János M. Bak writes that that amount would have only covered about 85% of the expenses of a military expedition against the Ottoman Turks, who had captured Constantinople and planned to invade Hungary.

[57] On 20 February, Ulrich triumphally returned to Vienna and vigorously reasserted his role as the young king's main advisor for Austrian affairs.

[74][73] Hunyadi only allowed the king to leave Temesvár after Ladislaus made him captain general and pledged that he would not take revenge for Ulrich of Celje's murder.

[77] Ladislaus appointed John Jiskra to be the commander of the royal army and left Hungary for Vienna, dragging the captive Matthias Hunyadi with him in early June.