The fall of Constantinople in 1453 (only 3 years before the Ottoman siege at Belgrade) sent panic and fear throughout Europe and the Christian world. The loss of Constantinople was regarded as a calamitous setback for Christian Europe and the crusades. The victorious Sultan Mehmet II, encouraged by his momentous victory at Constantinople, began an advance into the Balkans and northward in the hopes of defeating Hungary and reaching Western Europe. Mehmed II would take Serbia in 1454-55; and the following year with an army estimated to be 70,000 strong (other historians have estimated that Mehmed’s army may have been between 100,000-300,000 men), he launched what would be a long and arduous march to Belgrade.
Belgrade (Nándorfehérvár) was a key stronghold of the southern defense system of medieval Hungary. The epic battle between the Ottoman Empire and Hungary would come to significantly influence the subsequent history of Europe and the spread of Ottoman domination in the Balkans. János (John) Hunyadi, an influential and famous Hungarian military commander, politician and noble, took the responsibility for coordinating and controlling the defensive operations along the southern borders of Hungary (a position he was appointed to in 1441). Hunyadi, knowing of the Ottoman advance in the Balkans, left 7,000 of his soldiers in Belgrade to build and strengthen its defensive capabilities in May of 1456. In the buildup to the Ottoman siege, John of Capistrano, a Franciscan monk appointed by the pope to recruit as many troops as it was possible, crisscrossed the Kingdom of Hungary and Western European powers to raise a volunteer force. By June, 1456 Capistrano’s army and the Hungarian forces (numbering approximately 45,000-50,000 in total) arrived in Belgrade and began to take up their defensive positions north of the city.
Hunyadi was able to maintain his pre-eminent position for several years to a considerable degree due to the ever-present Ottoman menace. The defeat of Kosovo Polje was followed by a pause in hostilities. Sultan Murad, who had business to look after elsewhere, signed a treaty with the Hungarians in 1450 and this was confirmed by his successor, Mehmed II (1451-1481). However, it was soon apparent that the accession of Mehmed meant the beginning of a new phase of Ottoman expansion, which was to be much more successful than the previous ones. The first waves of this resurgent military threat soon reached Hungary. Constantinople fell in 1453, and Mehmed immediately transferred his residence from Adrianople to the newly conquered city. In 1454, when the peace of Oradea expired, he attacked Serbia and laid siege to Smederevo, Brankovi.’s capital. In the following year he renewed his attack, this time occupying the whole of Serbia with the exception of Smederevo. As the expedition of 1456 was to be directed against Belgrade, it was not surprising that Hunyadi would once again be pushed to the forefront of events as the potential saviour of the kingdom. His reputation may have been shaken by his defeats since 1444, but he was indisputably the only man capable of successfully opposing the Ottomans.
The preparations for a counter-attack began as early as 1453. Immediately after the fall of Constantinople, Pope Nicholas V proclaimed a crusade. The war against the Ottomans frequently emerged as a subject for discussion at the imperial diets in Germany in 1454-1455, although no definitive decision was made. Not surprisingly, Hungary was swept by a wave of panic, and the diet that assembled in January 1454 at Buda consented to large-scale measures in order to mobilise a national army. It proclaimed the general levy of the nobility, and renewed the institution of the militia portalis. Four cavalrymen and two archers were to be equipped by every 100 peasant holdings, a demand that surpassed all previous recruiting measures. But the projected offensive never took place; all that happened was that in the autumn of 1454 Hunyadi marched into Serbia at the head of a small army and defeated the forces left behind by the sultan at Krusevac. Planning continued in 1455 and the diet levied an extraordinary tax, but that was all that took place. The cause of the anti-Ottoman war was given renewed impetus by the new Pope, Calixtus III (1455-1458), who tried to mobilize the whole power of the Church in order to launch a new crusade. Although the princes of Europe turned a deaf ear to the Pope’s request, he nevertheless aroused enthusiasm among the common people in several places. He received much help from the Franciscans, who deployed the skills of their popular preachers in the service of the `holy war’. As a result of their unremitting zeal, by the summer of 1456 a huge crusading army, consisting mainly of Germans and Bohemians, had assembled in the area around Vienna, ready to march against the `infidels’.
However, this host never confronted the sultan, who began the siege of Belgrade on 4 July with an army which modern scholars have put at 60,000 to 70,000 men. Hunyadi, assisted by the Franciscan Giovanni da Capestrano, had successfully organised the castle’s defence and had assembled a significant army in the vicinity. In the region of 25-30,000 crusaders, `peasants, craftsmen and poor people’, rallied to Hunyadi’s camp under the influence of Capestrano’s impressive sermons.
One of Belgrade’s greatest advantages was its geographic location at the confluence of the Danube and Sava rivers. Mehmet would similarly take advantage of Belgrade’s position by sailing over 200 ships up the Danube river with canons, supplies, siege weapons and equipment. The Ottomans would even establish founderies in Serbia to build and manufacture canons to support the siege. Legend has it that the bells of Constantinople were melted and used to manufacture the canons used against Belgrade in 1456. With the Ottoman forces firmly in control of the river at this stage, the Ottomans blocked Belgrade off from the Danube with a chain of ships, moored upstream of the castle, and began placing their heavy guns outside the western walls of the fortress. The bombardment of the fortress would began in July. Hunyadi however anticipated this tactical move by Mehmed’s forces, and devised a cunning attack to retake control of the river.
On July 13, 1456, a Hungarian fleet of vastly inferior vessels broke the line of the Turkish fleet with the assistance of the fortress commander, Mihaly Szilágyi. Both Hunyadi and Szilágyi (who was Hunyadi’s brother-in-law), had river units that were anchored on the Sava River west of Belgrade and further north on the Danube – and therefore out of reach by the Ottoman forces. Both commander’s led a two-fronted attack against Mehmed II and defeated the Ottoman river armada. With the defeat of the Ottoman fleet, the Hungarians had control of the Danube again meaning the supply of needed reinforcements to Belgrade could be provided uninhibited. Hunyadi could then join his forces, camped about 30 kilometres north of Belgrade, with Szilágyi to increase the defensive capability of the fortress.
The continued Ottoman siege against Belgrade proved insufficient to deal a deciding blow to Hunyadi’s forces. Hunyadi was compelled to lead a defensive fight due to the lack of enough calvary forces to attack the Ottomans full-out. After almost ten days of unsuccessful sieges, on July 21, 1456 Mehmed ordered a full attack on the fortress. By the night of July 21 so many Ottoman attackers had been killed that chaos broke out among Mehmed’s ranks. The next morning (July 22, 1456) Hunyadi rode out of the stronghold with a small contingent and entered into hand to hand fighting with Medmed’s tired and beleaguered army. The Sultan sent 6,000 fresh troops into combat, but these troops could not defeat Hunyadi. Mehmed’s army experienced casualties in excess of 50,000 men and, after the Sultan himself became wounded in battle, ordered a general retreat to Sofia in Bulgaria.
The sultan withdrew with the remnants of his army and with memories that prevented him and his successors from launching an attack of the same dimensions for 65 years. News of this resounding victory soon reached the West. The day on which the Pope received the news, 6 August, the day of the Lord’s Transfiguration, was declared a general feast throughout the Christian world. He had previously ordered that all the bells should be rung at noon to encourage the soldiers, but his bull was not published until after the battle, and thus the tradition, which continues in Hungary to this day, is generally thought to be commemorative of the victory itself.
The victory presented an excellent opportunity for a counter-attack, especially in view of the fact that considerable forces were gathering in the heart of Hungary. But no offensive took place, because the crusaders were already on the edge of open revolt. Anger against the `powerful’, who had kept themselves far from the battle, had already been growing during the fighting. Agitation became so intense after the victory that Hunyadi and Capestrano decided to disband the army. Both of them soon died, however. On 11 August, Hunyadi fell victim to the plague that had broken out in the crusaders’ camp, and Capestrano followed him to the grave on 23 October.
Hunyadi was succeeded by his elder son, the 23 year-old Ladislaus. He seems to have inherited his father’s ambition and slyness, but apparently not his talent. Within a couple of days he found himself in conflict with the king and Cilli, who demanded that the castles and revenues that had been held by Hunyadi should be handed over. Cilli had himself appointed captain general of the realm. Together with the king, and at the head of the foreign crusaders who had recently arrived, he marched southwards with the aim of taking possession of Belgrade and the other stipulated fortresses. To preserve his position, the young Hunyadi decided upon an extremely hazardous course of action. At the assembly of Futog he feigned submission and then enticed his opponents into the castle of Belgrade. There, on 9 November 1456, he had Ulrich murdered by his henchmen, and made himself master of the king’s person. Hunyadi had himself appointed captain general, then took the king to Timisoara. Before being set free, the king was made to swear that the death of Count Cilli would never be avenged.
Ladislaus Hunyadi seems to have seriously miscalculated the possible consequences of his actions. The unprecedented murder turned everyone but his most determined followers against him: not only John Hunyadi’s enemies, like Garai, but also his friends and supporters, like Ujlaki and Orszag, agreed that Ladislaus should be bridled. Paying for perfidy with perfidy, they soon made their opponent believe that he had nothing to fear; and the king too showed himself a master of deception. On 14 March 1457, when Ladislaus was staying at Buda with his brother Matthias, both were arrested, together with their supporters. The royal council, functioning now in its capacity as supreme court, convicted the Hunyadi brothers of high treason, and on 16 March Ladislaus was beheaded in St George’s square in Buda. His supporters were pardoned, but Matthias was held by the king, who immediately left Hungary for Bohemia. The retaliation failed to bring about the desired consolidation, however. Hunyadi’s partisans, in possession of his family’s immense and still intact resources, reacted with open revolt. It was led by Matthias’s mother, Elisabeth Szilagyi, together with her brother, Michael, while the royal troops were commanded by Ujlaki and Jiskra. Fierce but indecisive fighting continued for months, and was ended only by the news of Ladislaus V’s premature death in Prague on 23 November 1457. Since the king had no lawful heir, the kingdom was once again left without a ruler.