Siege of Belgrade (1456)

The siege of Belgrade, or siege of Nándorfehérvár (Hungarian: Nándorfehérvár ostroma or nándorfehérvári diadal, lit. "Triumph of Nándorfehérvár"; Serbian Cyrillic: Опсада Београда, romanized: Opsada Beograda) was a military blockade of Belgrade that occurred 4–22 July 1456 in the aftermath of the fall of Constantinople in 1453 marking the Ottomans' attempts to expand further into Europe. Led by Sultan Mehmed II, the Ottoman forces sought to capture the strategic city of Belgrade (Hungarian: Nándorfehérvár), which was then under Hungarian control and was crucial for maintaining control over the Danube River and the Balkans.

As the "key to the realm", the castle of Belgrade was the largest and most fortified border stronghold of Hungary, regarded as the southern gate of the kingdom and being considered one of the strongest fortresses in Europe. Captain in Chief of Hungary, John Hunyadi, had garrisoned and strengthened the fortress city at his own expense. The Hungarian defenders, led by Michael Szilágyi, put up a determined resistance against the larger Ottoman army from 4 July. The siege lasted for several weeks, during which both sides suffered heavy losses. The defenders used innovative tactics, including heavy artillery and firearms, to repel the Ottoman assaults. On 14 July, Hunyadi's relief force destroyed a Turkish flotilla on the Danube, and Hunyadi entered to the fortress with fresh troops. The Ottomans launched a major assault on 21 July, but it was repulsed. Wounded Mehmed II was compelled to lift the siege and retreat on 22 July. This victory boosted the morale of European Christian forces and was seen as a turning point in their efforts as it provided a crucial buffer and temporarily halted Ottoman expansion towards Europe beyond the Balkans for 70 years.

John Hunyadi's successful defence of Belgrade earned him widespread acclaim and respect as a military leader though he died of the plague a few weeks later. The Ottomans would continue their expansion in other directions, and the struggle between the Ottoman Empire and European powers persisted for centuries. The battle's significance also extended beyond its immediate aftermath, as it demonstrated the importance of firearms and artillery in warfare, heralding a new era in military technology and tactics.