The epithet Corvinus (referring to the raven) was first used by the biographer of his son Matthias Corvinus of Hungary, but is also applied to John, is linked to the legend documented by Gáspár Heltai. This legend was that John was the bastard son of Hungarian king Sigismund of Luxembourg, and Vajk was a faithful soldier of his father for two decades. King Sigismund, after the death of his wife has met Erzébet Morzsinai, a virgin noblelady, and fell in love. In the morning, the king has given a royal ring to the lady, promising her that he will take care of the boy. After the boy has been born, the family took off to travel to Buda to the palace of Sigismund. During the trip, they took a rest, and the baby John was crying. Erzsébet has given him the ring to make him quiet, when a rook stole the ring. Erzsébet's brother then took his bow and shot the rook, but as miracle, the rook had not died, and the ring was taken back. Arriving at the royal court in Buda, Sigismund has filled the cradle with precious stones.
The legend should have solid ground, as his tought-to-be father, Vojcu had never had before coat of arms with rook, so suddenly he changed it for some reasons, and Wallachian tradition is not showing any tradition to rooks. The family of Vajk immediately received the estates of Hunyad, his education was funded by the king. His brother is also called John, with no particular reasons; John has been confused with him (also called Székely János, or John the Szekler) who died at about 1440. John's son, king Matthias had a statue of Sigismund in Visegrád and was claiming him as his grandfather.
Widely respected in Europe, he still gathered rivals throughout his lifetime, and was the object of the Ottoman Empire's hatred.
While still a youth, the younger John Hunyadi entered the retinue of Sigismund, who appreciated his qualities. (He also was the King's creditor on several occasions.) He accompanied the monarch to Frankfurt, in Sigismund's quest for the Imperial crown in 1410, took part in the Hussite Wars in 1420, and in 1437 drove the Ottomans from Semendria. For these services he received numerous estates and a seat in the royal council. In 1438 King Albert II made Hunyadi Ban of Severin. Lying south of the defensible southern frontiers of Hungary, the Carpathians and the Drava/Sava/Danube complex, the province was subject to constant harassment by Ottoman forces. Upon the sudden death of Albert in 1439, Hunyadi, arguably feeling Hungary needed a warrior king, lent his support to the candidature of young King of Poland Władysław III of Varna in 1440, and thus came into collision with the powerful Ulrich II of Celje, the chief supporter of Albert's widow Elizabeth II of Bohemia and her infant son, Ladislaus Posthumus of Bohemia and Hungary. He took a prominent part in the ensuing civil war and was rewarded by Władysław with the captaincy of the fortress of Belgrade (at that time, Nándorfehérvár) and the governorship of Transylvania. He shared the latter dignity with Mihály Újlaki.
In July, he vanquished a third Turkish army near the Iron Gates. These victories made Hunyadi a prominent enemy of the Ottomans and renowned throughout Christendom, and stimulated him in 1443 to undertake, along with King Władysław, the famous expedition known as the long campaign. Hunyadi, at the head of the vanguard, crossed the Balkans through the Gate of Trajan, captured Niš, defeated three Turkish pashas, and, after taking Sofia, united with the royal army and defeated Sultan Murad II at Snaim. The impatience of the king and the severity of the winter then compelled him (February 1444) to return home, but not before he had utterly broken the Sultan's power in Bosnia, Herzegovina, Serbia, Bulgaria, and Albania.
No sooner had he regained Hungary than he received tempting offers from Pope Eugene IV, represented by the Legate Julian Cesarini, from Đurađ Branković, despot of Serbia, and Gjergj Kastrioti, prince of Albania, to resume the war and realize his ideal of driving the Ottomans from Europe. All the preparations had been made when Murad's envoys arrived in the royal camp at Szeged and offered a ten years' truce on advantageous terms. Branković bribed Hunyadi -he gave him his vast estates in Hungary- to support the acceptance of the peace. Cardinal Julian Cesarini found a traitorous solution. The king swore that he would never give up the crusade, so all future peace and oath was automatically invalid. After this Hungary accepted the Sultan's offer and Hunyadi in Władysław's name swore on the Gospels to observe them.
Two days later Cesarini received tidings that a fleet of Venetian galleys had set off for the Bosporus to prevent Murad (who, crushed by his recent disasters, had retired to Anatolia) from recrossing into Europe, and the cardinal reminded the King that he had sworn to cooperate by land if the western powers attacked the Ottomans by sea. In July the Hungarian army recrossed the frontier and advanced towards the Black Sea coast in order to march to Constantinople escorted by the galleys.
Branković, however, fearful of the sultan's vengeance in case of disaster, privately informed Murad of the advance of the Christian host, and prevented Kastrioti from joining it. On reaching Varna, the Hungarians found that the Venetian galleys had failed to prevent the transit of the Sultan - indeed, the Genoese transported the Sultan's army (and received, according to legend, one gold for each soldier shipped over). Hunyadi, on November 10 1444, confronted the Ottomans with four times the Hungarian forces. Nevertheless, victory was still possible in the Battle of Varna as Hunyadi with his superb military skills managed to route both flanks of the Sultan's army. At this point, however, king Władysław, who up to that point had remained in the background and relinquished full leadership to Hunyadi, assumed command and with his bodyguards carried out an all-out attack on the elite troops of the Sultan, the Janissaries. The Janissaries readily massacred the king's men, also killing the king, exhibiting his head on a pole. The king's death caused disarray in the Hungarian army, which was subsequently routed by the Ottomans; Hunyadi himself narrowly escaped. On his way home, Vlad II Dracul of Wallachia imprisoned Hunyadi; only the threats of the palatine of Hungary brought the voivode, theoretically an ally of Hunyadi against the Ottomans, to release him.
In 1448 he received a golden chain and the title of Prince from Pope Nicholas V, and immediately afterwards resumed the war with the Ottomans. He lost the two-day Second Battle of Kosovo (October 7-10 1448, owing to the treachery of Dan II of Wallachia, then pretender to the throne, and of his old rival Branković, who intercepted Hunyadi's planned Albanian reinforcements led by Gjergj Kastrioti, preventing them from ever reaching the battle. Branković also imprisoned Hunyadi for a time in the dungeons of the fortress of Smederevo, but he was ransomed by his countrymen and, after resolving his differences with his powerful and numerous political enemies in Hungary, led a punitive expedition against the Serbian prince, who was forced to accept harsh terms of peace.
In 1450 Hunyadi went to the Hungarian capital of Pozsony to negotiate with Holy Roman Emperor Frederick III the terms of the surrender of Ladislaus V, but no agreement could be reached. Several of John Hunyadi's enemies, including Ulrich II of Celje, accused him of conspiracy to overthrow the King. In order to defuse the increasingly volatile domestic situation, he relinquished his regency and the title of regent.
On his return to Hungary at the beginning of 1453, Ladislaus named him count of Beszterce and Captain General of the kingdom. The king also expanded his coat-of-arms with the so-called Beszterce Lions.
Meanwhile, the Ottoman issue had again become acute, and, after the fall of Constantinople in 1453, it seemed natural that Sultan Mehmed II was rallying his resources in order to subjugate Hungary. His immediate objective was Nándorfehérvár (today Belgrade). Nándorfehérvár was a major castle-fortress, and a gate keeper of south Hungary. If this stronghold fall, there is a clear way to the heart of Central-Europe. Hunyadi arrived at the siege of Belgrade at the end of 1455, after settling differences with his domestic enemies. At his own expense, he restocked 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 proceeded to form a relief army, and assembled a fleet of two hundred ships. His main ally was the Franciscan friar, Giovanni da Capistrano, whose fiery oratory drew a large crusade made up mostly of peasants. Although relatively ill-armed (most were armed with farm equipment, such as scythes and pitchforks) they flocked to Hunyadi and his small corps of seasoned mercenaries and cavalry.
On July 14 1456 the flotilla of corvettes assembled by Hunyadi destroyed the Ottoman fleet. On July 21, Szilágyi's forces in the fortress repulsed a fierce assault by the Rumelian army, and Hunyadi pursued the retreating forces into their camp, taking advantage of the Turkish army's confused flight from the city. After fierce but brief fighting, the camp was captured, and Mehmet raised the siege and returned to Istanbul. With his flight began a 70 year period of relative peace on Hungary's southeastern border.
However, plague broke out in Hunyadi's camp three weeks after the lifting of the siege, and he died August 11. He was buried inside the (Roman Catholic) Cathedral of Alba Iulia (Gyulafehérvár), next to his elder brother John.
The rise of nationalism has led to hero images of John Hunyadi in the discourse of several local nationalities – each in its own way has claimed him as their own. Along with his son Matthias Corvinus, John has acquired a presence in modern Romania's political culture (images that focus on the Vlach origin rather than their careers within Hungary or on their presence as outsiders in the politics of Wallachia and Moldavia, although Hunyadi was responsible for establishing the careers of both Stephen III of Moldavia and the controversial Vlad III of Wallachia). John Hunyadi is traditionally considered a national hero in Hungary.
Among John's noted qualities, is his regional primacy in recognizing the insufficiency and unreliability of the feudal levies, instead regularly employing large professional armies. His notable contribution to the development of the science of European warfare included the emphasis on tactics and strategy in place of over-reliance on frontal assaults and mêlées.
His diplomatic, strategic, and tactical skills allowed him to serve his country well. After his death, Pope Callixtus III stated that "the light of the world has passed away", considering his defense of Christendom against the Ottoman threat. The same pope has ordered the noon bell to be rung for the memory of Hunyadi's victory in siege of Belgrade, and to mark the resistance to Islamic progression inside Europe.