The pressure of the Austrian estates to free Ladislaus had grown from 1450.

In 1451, Frederick had successfully faced an insurrection by Austrian nobles who demand possession of Ladislas, and had retained his regency over the boy.

The nobles enter into the Mailberg Confederation under the leadership of Ulrich, Baron of Eyczing, and Ulrich II, Princely Count of Celje.

After his coronation, in Rome, as Holy Roman Emperor in 1452, Frederick is surrounded in his capital at Wiener Neustadt, Austria, by sixteen thousand troops under Ulrich of Cilli, a cousin of Ladislas and a power in Austria.

Upon Frederick’s surrender of Ladislas, Ulrich takes the twelve-year-old monarch to Vienna.

Ulrich of Celje, a Slovenian magnate and heir to Bosnia, the cousin of Ladislaus's mother, had prevailed against Eyczing and become the new guardian of the child, effectively ruling in his stead.

A coup removes Ulrich from power, but he nonetheless continues to counsel Ladislas.

On October 28, 1453, at the age of thirteen, Ladislaus Postumus is finally crowned King of Bohemia, after which he will lived mainly in Prague or Vienna.

Ulrich of Celje and Ladislaus remain indifferent to the threat posed in Hungary by the Turks, and Ulrich becomes increasingly hostile towards John Hunyadi, who is bearing the main burden of the battles against the Ottomans.

Ladislas, opposed by both Hunyadi and George of Poděbrady, asserts his majority to rule over his Bohemian and Hungarian kingdoms in 1455, but George retains effective control of Bohemia.

Ulrich II of Celje, the most powerful member of the Cilli family of Lower Styria, is named by King Ladislaus V of Hungary to Hunyadi’s office of Captain General of Hungary after the death of his rival.

Ulrich, now possessed of significant power, declares Hunyadi’s son László responsible for the debts alleged to be owing by the elder Hunyadi to the state; but László defends himself so ably at the diet of Futak (October 1456) that Ulrich feigns a reconciliation, promising to protect the Hunyadis on condition that they first surrender all the royal castles entrusted to them.

A beginning is to be made with the fortress of Nándorfehérvár (now Belgrade, Serbia) of which László is commandant.

While admitting Ladislaus V and Ulrich, László excludes their army of mercenaries.

On the following morning (November 9, 1456) Ulrich dies at the hands Celje of Hunyadi's men in unclear circumstances.

With him dies the male line of the Counts of Celje.

The terrified young king thereupon pardons Hunyadi, and at a subsequent interview with his mother at Temesvár swears that he will protect the whole family.

Đurađ Branković, Serbian despot from 1427 to 1456 and a baron of the Kingdom of Hungary, is the first of the House of Branković to hold the Serbian monarchy.

Deemed by contemporaries as the richest monarch in all of Europe; the French knight Bertrand de la Broquierre had stated the despot's annual income from the gold and silver mines of Novo Brdo (near Gnjilane in Kosovo) amassed to about two hundred thousand Venetian ducats.

Among other of the Despot's sources of income, there are his possessions in the Kingdom of Hungary, for which expenses are covered by the Hungarian crown.

The annual income from them alone is estimated to fifty thousand ducats.

His elder daughter Mara had become one of the wives of Murad II of the Ottoman Empire; his younger daughter Catherine is the wife of the murdered Ulrich II of Celje.

Đurađ dies on December 24, 1456, and is succeeded by his son Lazar, his elder sons Grgur and Stefan having been blinded in 1441 on Murad’s orders.