On August 29, 1526, a Christian army1 lost a battle with Ottoman Turks near Mohács, a small city in southern Hungary. The battle itself was short, starting only at 4 PM and ending by sunset. The Turkish Sultan, Suleiman the Magnificent, didn’t even consider his victory to be decisive, and it took him a few days to learn that, after a hundred years of a bloody indecisive tug-of-war, he strategically defeated the Hungarian kingdom in just a few hours. His opponent, Louis II Jagiello, was dead at a mere 20 years of age, and he had no heir.
To add insult to injury, young Louis didn’t even fall in combat. Once the battle turned for the worse, he listened to the advice of his retinue and fled the battlefield in order to save his life and kingdom(s). But in the dark of the night, his horse fell from a muddy bank into a swollen creek (it had rained for two weeks nonstop prior to the battle) and pinned the king underneath its body, causing him to drown. Not the best death for a Christian knight and king of the early 16th century, but that is just fate. We don’t know our own ends either, commoners and nobles alike.
This was a moment that changed the history of Europe. Prior to Louis’ death, he wore the Czech, the Hungarian and the Croatian crown, and Poland was ruled by his uncle Sigismund the Old. Although the Jagiellonian kingdoms remained legally separate and had their own laws, it was still one helluva realm for a single dynasty to rule, the end result of more than a hundred years of the Jagiellonian drive to establish themselves on the European scene. Originating as a pagan Lithuanian noble family which accepted Christianity in 1385, they adapted the name of their patriarch, Jogaila, to the Polish-sounding Jagiello. They also helped found the Polish-Lithuanian Commonwealth, a behemoth of a nation whose borders enclosed much of contemporary Belarus and Ukraine as well. A hundred years later, the Jagiellonian dynasty ruled a combined territory which touched on three seas (the Baltic, the Black and the Adriatic).
There was only one little, well, big problem: the Ottoman Turks, on their holy mission to conquer as much as they could for Allah and the Sultan, who was also considered the Caliph of the Faithful. And by that time, they had made serious inroads into Europe itself.

In order to conquer Europe, the Turks had to destroy the Eastern Roman Empire first, which we nowadays know as Byzantium2. That took them several centuries, and this process was massively helped along by the unholy Fourth Crusade of 1202-1204, which the Venetians redirected against Constantinople, their main competitor in the Mediterranean. (This might have been the worst, dirtiest and most criminal mistake that the medieval Christendom committed against itself.) During the 15th century, the last remnants of the Eastern Roman Empire were swept away by the Ottoman military might, and the next logical stop was the Balkans.
The Balkan kingdoms and princedoms put up a fight, but they were usually no match for the Ottomans, with the exception of one particular Romanian guy called Vlad the Impaler, who really loved to impale POWs onto spikes by the thousands; his terrible reputation outlived him by entire centuries and today, he is better known as the model for Dracula. Anyway, the next really dangerous opponent was the Hungarian kingdom, a rich, but also rather disunited country where the King could never completely rely on the support of his magnates. The Hungarians were, nevertheless, good at fighting and capable of big feats in the field; their cavalry was, by all measures, top-notch.
The trouble with the Ottomans was that they were no amateurs either. Although they certainly didn’t lack for religious fanaticism, they also acquired a lot of contemporary technology from Italian or Greek engineers and, in the early 16th century, they were probably the most technologically advanced military power in all of Europe; especially their artillery was modern and deadly. Their shock troops, the Janissaries, consisted of once-kidnapped young Christian boys who were converted to Islam and raised far from their homelands, thus losing any religious, tribal, familial or clannish loyalties in the process; the end result being cohesive and well-trained units that could sometimes turn the tide of the battle on their own.
One sordid detail: quite a lot3 of the firearms that the Ottomans obtained were sold to them by private Hungarian merchants. Pecunia non olet, in Rome as well as in Buda, Pest4 and a hundred other cities.
Against such a formidable foe, any pitched battle would have been a high-risk endeavor even if the force ratio approached 1:1. But at Mohács, the numbers were at least 2:1 and maybe up to 3:1 in favor of the Turks, which means that the odds for Christian victory were really low from the very start.
No one really blames young Louis for the defeat, at 20 he wasn’t an experienced warrior. His actual commander was a noble named Pál Tomori. At 50 years of age, he was the most experienced military leader in all of Hungary and the Pope himself had earlier forced him to abandon his religious career (he was a monk) and return to the army, in order to improve Hungary's chances.
Nevertheless, the Hungarians were divided, in a self-defeating way. It would be logical to wait until their entire army had assembled, and only then challenge Suleiman, preferably in optimal conditions. But a lot of the nobles present at Mohács pressed for a battle here and now, eager to reap some battlefield glory. Tomori ultimately gave way, even though the terrain could hardly have been worse. After two weeks of almost constant rains, in a swampy area which limited the ability of the cavalry to maneuver, the two armies clashed.
The Hungarians probably hoped to destroy the vanguard of Suleiman’s army in isolation, but they were mistaken; they encountered the entire Ottoman host at once, and, all their personal bravery notwithstanding, were thoroughly routed. The disciplined Janissary fire proved to be especially deadly to the knights charging the Ottoman lines; at this moment of history, no amount of armor could protect its wearer from an arquebus shot, and the Janissaries were trained to shoot devastating volleys.
The overall result: the king dead, Pál Tomori dead, much of the Hungarian nobility dead, the kingdom itself - almost dead. The next Hungarian ruler, John Zápolya, became a Turkish vassal. After his death, the Turks took Buda directly (1541) and held it until 1686.

There is a fascinating what-if here. What if at least young Louis survived and reached safety, and the Jagiellonian dynasty continued to rule all their kingdoms, even though now with a really formidable Turkish problem on their southern flank?
This was the time of the Reformation, and the Jagiellonians could well have converted to the new faith, taking Poland with them. (Just imagine Protestant Poland.) The Austrian Hapsburgs could have remained confined to Austria proper: no Austria-Hungary ever, no geopolitical ambitions in the Balkans, no shots in Sarajevo. In the 18th century, the Prussians might have been kept in check, as taking on the entire Jagiellonian realm at once would have been too much even for the pugnacious Frederick the Great. Russia might have been kept on the outskirts of Europe forever, and the German Empire might have never been. Who knows what the repercussions in Western Europe would have been.
This alternate path of history died in the mud of a dark brook in the Pannonian plain one night. There are hours when centuries happen, and this was one of them.
The extent of AI use in this article: 29 grammatical errors and bad word choices corrected. Three factual mistakes corrected. No editing.
I will use the description Christian, because a) that is what the contemporaries used, b) this is probably the closest-fitting description to an army composed of multiple nationalities, from the Hungarians, the Poles, the Czechs and the Silesians, to Italian mercenaries paid for by the Pope himself.
This is a somewhat bizarre name, as its own inhabitants still called themselves the Romans and even their Turkish opponents respected the name.
A later edit after a discussion with a reader: this might be overstating the case. We know that the problem existed and that it led to a ban by the Hungarian Diet, but not its exact level of seriousness, neither how successful the enforcement of the ban actually was. The Ottomans were able to produce much of their weaponry themselves, but of course buying extra guns from abroad enabled them to arm up faster.
Contemporary Budapest is a union of two cities, Buda and Pest. Buda was the royal one, Pest was the merchant one. Built on opposite riverbanks of the Danube, they only became one city in 1873.



Somehow the words "Protestant Poland" feel like a self-contained punchline.
Short battle, long-term consequences...