First of all, let’s not confuse this battle with the 1687 Battle of Mohács, which we’ve previously mentioned. Aside from the fact that the two battles are ~160 years apart, they also led to two completely different outcomes. That Battle of Mohács was a decisive Ottoman defeat that caused Hungary to come under the control of the Habsburgs, cost the life (thanks to a subsequent Janissary mutiny) of the Grand Vizier at the time, and ultimately resulted in the deposition of the Ottoman Sultan Mehmed IV. This Battle of Mohács was a decisive Ottoman victory that brought a big chunk of Hungary under Ottoman control for the next 160 years, ended the royal line of the Jagiellonian dynasty that ruled Hungary, Croatia, and Bohemia, and ultimately brought those kingdoms into the Habsburg orbit (at least nominally, since Croatia and much of Hungary were under Ottoman control). Basically, Mohács saw both the beginning and the end of Ottoman control over Hungary, which is something to be said for a town that numbers about 18,000 residents today. But the truth is that Mohács, located in the extreme southern part of Hungary right on the Danube River, is an obvious place to meet an invading army, or to drive an invading army out of Hungary altogether.
The Ottoman Empire in the 16th century was very much an expansionist enterprise, so there’s no mystery why Sultan Suleyman I (d. 1566) wanted to conquer Hungary: it was there, on his frontier, waiting to be conquered. He’d already taken some Hungarian-controlled territory, in particular the city of Belgrade (now in modern Serbia) in 1521. But Suleyman (AKA Suleyman the Magnificent, if you’re wondering about his later reputation) also wanted to get after the Habsburgs, both to counter their competing expansionism (which he rightly saw as a threat) and because Suleyman was engaged in serious diplomacy with King Francis I of France (it should have been a medieval European law, maybe a Church law, that no king of France could ever be named “Francis,” but I digress), which would eventually lead to a formal alliance in 1536. The French were entirely opposed to the Habsburgs (the fact that they entered into an alliance with the Muslim Ottomans shows how deep their enmity ran), and Francis agitated for Suleyman to attack them. Which Suleyman was happy to do, because, again, he was running an expansionist empire.
The Hungarian (and Bohemian and Croatian) King, Louis II (d. — SPOILER ALERT — 1526), had married Mary of Habsburg in 1515, the sister of Charles V, who became King of Spain in 1516 and Holy Roman Emperor in 1519. I mention that only because it will come up again later. He called up the royal army and then proceeded to deploy it so incompetently that you have to wonder if he was affected by low blood sugar.
You know, because he was the king of HUNGARY! Get it?
No, that’s OK; I’ll show myself out.
Anyway, Louis and his commanders didn’t know where Suleyman was leading his force (which was between 50,000 and 100,000 men strong — most modern scholarship leans toward the higher of those two figures), so he split his army into three: one force under nobleman John Zápolya east to Transylvania, another force of mostly Croatian knights, and his own army that numbered maybe as many as 30,000 men and waited in the Hungarian capital of Buda (the western side of the modern city of Budapest). By the time it became clear that Suleyman was headed in Louis’ direction, it was too late for the other two parts of the army to come to his aid.
Louis then made the almost inexplicable decision to march out to meet the Ottomans near Mohács, on a wide-open swampy plain. I don’t know if he figured the swampy terrain would reduce the mobility of the Ottoman cavalry, but even if he was right it wouldn’t have mattered, because the core of the Ottoman army was its firearm-wielding Janissary infantry, not its cavalry. Choosing to meet a much larger army (and much better equipped; the Ottomans were using firearms while the Hungarians were relying on medieval heavy cavalry–which is kind of amazing considering that, less than a century earlier, the Hungarian army may have actually been more technologically advanced than the Ottomans) in an open field was…well, it was an interesting choice. Louis’ final mistake came when the Ottoman army began to arrive at Mohács, when there may have been a window (thanks to the terrain) in which Louis could have marshaled his whole army and attacked a portion of the Ottoman force while they were tired from their march and before they had a chance to bring their full army to bear. The Hungarians elected to wait, for some reason. Probably some kind of chivalric honor bullshit.
You already know who won the battle, but those Hungarian knights did do some damage, routing the first Ottoman wave of Balkan conscripts before flanking attacks by the regular Ottoman cavalry and musket volleys from the Janissaries began to pick them apart. The whole battle lasted only a few hours, starting in the early afternoon and ending by nightfall. Louis tried to flee under cover of darkness, but he was thrown from his horse into a river and drowned, weighed down by all his heavy yet fairly obsolete plate armor (seriously; it was more likely that Louis’ armor would cause him to drown than that it would protect him from Janissary musket fire). The whole thing was so easy that Suleyman halted his army at Mohács because he figured there had to be a bigger Hungarian force out there, heading his way. Eventually the Ottomans marched to Buda and sacked the place. Most of Hungary was now theirs, though it turned out to be kind of a mixed blessing. Control of Hungary meant steady Hungarian resistance to Ottoman rule and a constant stream of Habsburg attacks on Ottoman Hungary throughout the 16th century, which weren’t successful but sucked up imperial attention, money, and manpower.
It fell to the Hungarian nobles to elect a new king, but since Louis had no son this was not such an easy task. One group of nobles elected the Habsburg Archduke of Austria, and Louis’ brother-in-law, Ferdinand I. He didn’t have much claim on central or eastern Hungary, which were now firmly in Ottoman hands, but he did scoop up western Hungary, Bohemia, and those parts of Croatia that weren’t also under Ottoman control. Another group, with Ottoman support, elected John Zápolya, who was also Louis’ brother-in-law. Eventually the Habsburg claim would win out, but not until the next Battle of Mohács. But that outcome only shifted control of Hungary from one empire to another; there wouldn’t be an independent Hungarian polity again until after World War I. And that’s probably the longest-lasting impact of this 1526 Battle of Mohács, its impact on Hungary. What had once been a significant European power hasn’t gotten anywhere near that status since.