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Mehmed II earned the epithet Fatih or “the Conqueror” when he captured Constantinople in 1453, and it’s lucky for him that he did, really. If he didn’t already have a slick nickname by the time of his failed effort to capture Belgrade, I can imagine he might have been saddled with a much less flattering one instead. Well, at least behind his back, anyway.
After Constantinople, Mehmed’s gaze naturally kept moving west (he was particularly keen on reuniting the “two Romes” by capturing the actual Rome), and the next major target on the road to central Europe was Hungary. The regular reader and/or fan of late medieval European history will note that 15th century Hungary was a genuine military heavyweight, capable of slugging it out with the Ottomans or, really, just about anybody. They owed their military success to two factors: their early adoption of firearms and field artillery (and of innovative tactics employing those weapons like the “wagon fortress”), and the presence of a great general, Transylvanian warlord John Hunyadi (d. 1456 but that’s not a spoiler). Hunyadi had beaten the Ottomans several times in the early 1440s, and though the Ottomans had achieved a measure of revenge by defeating him at the Battle of Varna in 1444 and the (Second) Battle of Kosovo in 1448, he was still around and his army was still a pretty tough nut to crack.
The road through Hungary began at Belgrade. The Ottomans had already swallowed up most Serbian territory, but Belgrade, or Nándorfehérvár in Hungarian, controlled the border. Unfortunately for Mehmed, Hunyadi knew the Ottomans were coming and began making preparations for a siege at Belgrade months before they arrived. He put together a small force to garrison the fortress, and then began traveling around Hungary to raise a large relief army. This army was joined by a Crusader army, made up primarily of local residents, that had been raised by a Franciscan preacher named John of Capistrano (d. 1456, also not a spoiler). The future Saint John took time out of his favorite hobby, traveling from city to city inciting anti-Jewish pogroms (look it up), to preach Pope Calixtus III’s (d. 1458) call for a Crusade to drive the Ottomans back out of Europe. He focused his efforts on Hungarian peasants and small landowners, and was able to recruit thousands of men—tens of thousands, even—to march to Belgrade to resist the Ottoman assault. Most of them were too poor to afford proper arms and armor, but any warm body would help.
Even with his advance preparations, Hunyadi wasn’t ready when Mehmed’s forces arrived at Belgrade on July 4, 1456. The maybe 7000 man garrison was vastly outnumbered, as much as 10-to-1, by the Ottomans, but they had one big advantage on their side: Belgrade castle. This was a massive fortress with three different levels and sturdy walls. Even with an undermanned garrison defending it would take considerable time for the Ottomans to break through the defenses. While Hunyadi wasn’t quite in position to counter the Ottoman offensive when they arrived, he was going to be able to come to Belgrade’s relief long before Mehmed would be able to get through those walls. In fact, it only took him 10 days—his relief force arrived on July 14 and began by punching through the Ottoman fleet blockading the city, so that he could bring in his army and lots of much-needed supplies.
An Ottoman miniature of the Siege of Belgrade (Wikimedia Commons)
Hindsight is 20/20 of course, but when Hunyadi was able to break through the naval blockade and reinforce/resupply Belgrade, it was probably time for Mehmed to pack it in and head home. He didn’t. On July 21 he launched a massive assault against the city that broke through the first line of defense into the lower city, then broke through the second line of defense into the upper city. So far, so good, if you’re an Ottoman fan. However, as the Ottoman vanguard, made up mostly of Janissaries, began fighting the Hungarian defenders of Belgrade’s citadel, Hunyadi ordered his men to set fire to the lower city. The flames caused the Janissaries to become separated from the troops that were supposed to follow them into the upper city, and without reinforcements they were mowed down by the Hungarians.
Mehmed still doesn’t seem to have been ready to lift the siege, but on July 22 all those peasant soldiers who had been recruited by John of Capistrano marched out of the city and toward the Ottomans. John of Capistrano is said to have gone out of the city to try to order his men to return to its defenses, but when they kept marching he apparently decided “to hell with it,” turned around, and led them on a charge at the Ottoman lines. Hunyadi was then forced to support their charge lest he lose desperately-needed soldiers on a futile action, so his army entered the field as well. In response, the Ottomans…panicked. That didn’t happen very often throughout the really dominant portion of Ottoman history, but here it did. Soldiers began to run. The Janissaries tried to stop the retreat to no avail. Mehmed himself tried to turn his line around, but he was wounded and had to be carried from the field. The Hungarians stopped their pursuit and returned to the city before nightfall, and the Ottomans took advantage of this respite to retreat in good order back to Constantinople.
Belgrade might have been John Hunyadi’s greatest victory, but it was also his last, as he died in August of a plague that hit the Hungarian army. John of Capistrano died in October, also of plague. The successful defense of Belgrade stemmed the Ottoman tide, and though Mehmed made other attempts to advance westward, for example his brief capture of Otranto in 1480, none of them were able to stick so long as Belgrade was still there to hold the line. Which is not to say that Mehmed just sat on his thumbs for the next couple of decades. He may not have been able to do much more expanding, but he was able to consolidate Ottoman gains in the Balkans. It wasn’t until 1521 when the Ottomans, now under Suleyman I (d. 1566), were finally able to take Belgrade and reopen their road to the west. That road would finally end at Vienna, in 1529, though of course nobody knew that at the time.