The Ottoman issue has again become acute, and, after the fall of Constantinople in 1453, it seems natural that Sultan Mehmed II is rallying his resources in order to subjugate Hungary.

The sultan has initiated new pressure on the Hungarians and other European Christians, abducting some fifty thousand Serbs.

John Hunyadi, whose influence has waned in Hungary, had not been able to launch a counterattack against the Turks, nor could he go to the aid of Constantinople during the Turkish onslaught in 1453.

Mehmed’s immediate objective is Nándorfehérvár (today Belgrade), a major castle-fortress, and a gate keeper of south Hungary.

The fall of this stronghold would open a clear way to the heart of Central Europe.

Hunyadi had arrives at the siege of Nándorfehérvár at the end of 1455, after settling differences with his domestic enemies.

At his own expense, he restocks the supplies and arms of the fortress, leaving in it a strong garrison under the command of his brother-in-law Mihály Szilágyi and his own eldest son László Hunyadi.

He proceeds to form a relief army, and assembles a fleet of two hundred ships.

His main ally is the Franciscan friar Giovanni da Capistrano (known today as St. John of Capistrano), whose fiery oratory has drawn a large crusade made up mostly of peasants.

Although relatively ill-armed (mostly with farm equipment, such as scythes and pitchforks) they flock to Hunyadi and his small corps of seasoned mercenaries and cavalry.

The flotilla assembled by Hunyadi destroys the Ottoman fleet on July 14, 1456.

On July 21, Szilágyi's forces in the fortress repulse a fierce assault by the Rumelian army, and Hunyadi pursues the retreating Ottoman forces into their camp, taking advantage of the Turkish army's confused flight from the city.

After fierce but brief fighting, the camp is captured, and Mehmed lifts the siege and returns to Istanbul.

A seventy-year period of relative peace on Hungary's southeastern border begins with his flight.

However, plague breaks out in Hunyadi's camp three weeks after the lifting of the siege, and he dies on August 11.

On his deathbed, Hunyadi says, “Defend, my friends, Christendom and Hungary from all enemies... Do not quarrel among yourselves. If you should waste your energies in altercations, you will seal your own fate as well as dig the grave of our country.”

He is buried in the Roman Catholic Cathedral of Gyulafehérvár (now: Alba Iulia) next to his younger brother, John the Younger.

Sultan Mehmet II pays him tribute: "Although he was my enemy I feel grief over his death, because the world has never seen such a man."

The death, amid rumors of poisoning, of the young Habsburg king, Ladislaus Posthumus in November of 1457 had ended the two-year struggle between Hungary's various barons and its king.

George of Poděbrady, governor of Bohemia and friend of the Hunyadis who aims to raise a national king to the Magyar throne, has taken hostage Janos Hunyadi’s younger son Matthias Corvinus.

Knighted at the siege of Belgrade in 1456, Matthias had married Elizabeth of Celje, the only known daughter of Ulrich II of Celje and Catherine Cantakuzina; her maternal grandparents were Đurađ Branković and Eirene Kantakouzene.

But the young Elizabeth had died in 1455, before the marriage was consummated, leaving Matthias a widower at the age of fifteen.

Poděbrady has treated Matthias hospitably and affianced him with his daughter Kunhuta, but still detains him, for safety's sake, in Prague, even after a Magyar deputation has hastened thither to offer the youth the crown.

Matthias takes advantage of the memory left by his father's deed, and by the general population's dislike of foreign candidates; most of the barons, furthermore, consider that the young scholar will be a weak monarch in their hands.

An influential section of the magnates, headed by the palatine Ladislaus Garai and by the voivode of Transylvania, Miklós Újlaki, who had been concerned in the judicial murder of Matthias's brother László, and hates the Hunyadis as semi-foreign upstarts, are fiercely opposed to Matthias's election; however, they are not strong enough to resist against Matthias's uncle Mihály Szilágyi and his fifteen thousand veterans.

Thus, over the elections of Emperor Frederick II, who seeks to retain Habsburg control of Bohemia, Matthias is elected king by the Diet on January 20, 1458.

Poděbrady releases him under the condition of marrying his daughter (later to be known as Catherine).

On January 24, 1458, forty thousand Hungarian noblemen, assembled on the ice of the frozen Danube, unanimously elect Matthias Hunyadi king of Hungary, and on February 14 the new king makes his state entry into Buda.

This is the first time in the medieval Hungarian kingdom that a member of the nobility, without dynastic ancestry and relationship, mounts the royal throne.

The Ottomans and the Venetians threaten Hungary from the south, the emperor Frederick III from the west, and Casimir IV of Poland from the north, both Frederick and Casimir claiming the throne.

The Czech mercenaries under Giszkra hold the northern counties and from thence plunder those in the center.

Meanwhile Matthias's friends have only pacified the hostile dignitaries by engaging to marry the daughter of the palatine Garai to their nominee, whereas Matthias refuses to marry into the family of one of his brother's murderers, and on February 9 confirms his previous nuptial contract with the daughter of Poděbrady, …

…who, chosen unanimously on February 27 by the estates of Bohemia, ascends the throne on March 2, 1458.

The struggle in Bohemia of the Hussites against the papal party has continued without interruption.

Podebrady’s position had become a very difficult one when the young king Ladislaus, who was crowned in 1453, had expressed his pro-Roman sympathies, though he had recognized the compacts and the ancient privileges of Bohemia.

Even the adherents of the papal party had voted for him, however, some in honor of his moderate policies, and some in deference to popular feeling, which had opposed the election of a foreign ruler.

The struggle between Hungary’s young king and the magnates, reinforced by Matthias's own uncle and guardian Szilágyi, has been acute throughout 1458, but Matthias, who began by deposing Garai and dismissing Szilágyi, and then proceeded to levy a tax, without the consent of the Diet, in order to hire mercenaries, has easily prevailed, recovering the Golubac Fortress from the Ottomans, successfully invading Serbia, and reasserting the suzerainty of the Hungarian crown over Bosnia.

Wallachia’s Vlad Ţepeş, whom the Pope holds in high regard, is the only European leader to have shown enthusiasm for the Pope’s crusade against the Ottomans.

Because of a lack of enthusiasm showed by Europeans for the crusade, Mehmed takes the opportunity to take an offensive stand.

Ţepeş's only ally, Mihály Szilágyi, is captured by the Turks while traversing Bulgaria in 1460.

Szilágyi's men are tortured to death, while Szilágyi is killed by being sawn in half.

Later this year, Mehmed sends envoys to Ţepeş to urge him to pay the delayed tribute.

Ţepeş provokes Mehmed by having the envoys killed and in a letter dated September 10, 1460, addressed to the Transylvanian Saxons of Kronstadt, he warns them of Mehmed's invasion plans and asks for their support.

Ţepeş has not paid the annual tribute of ten thousand ducats since 1459.

In addition to this, Mehmed has asked him for five hundred boys that are to be trained as janissaries.

Ţepeş refuses the demand, and the Turks cross the Danube and start to do their own recruiting, to which Ţepeş reacts by capturing the Turks and impaling them.