If you’re interested in history and foreign affairs, Foreign Exchanges is the newsletter for you! Sign up for free today for regular updates on international news and US foreign policy, delivered straight to your email inbox, or subscribe and unlock the full FX experience:
The Battle of Varna in 1444 was arguably the most important Ottoman victory in Europe prior to their conquest of Constantinople, especially if you consider its effects alongside those of the (second) Battle of Kosovo in 1448. The Ottoman success at Varna shattered a Hungarian-Polish alliance that had been formed to counter the Turkish threat. That alliance was such a big deal that Pope Eugenius IV (d. 1447) gave it the Church's official imprimatur, which is why you sometimes find the Battle of Varna discussed in the context of something called the "Crusade of Varna," even though the "crusade" consisted basically of a couple of preliminary engagements followed by this one major battle. The end of the "crusade" and the alliance behind it had huge implications for Europe, in that it gave the Ottomans time to focus on Constantinople, which, despite the near-irrelevancy of the Byzantine Empire by the mid-15th century, was still the big prize.
The Crusade of Varna, which is also also known as "the Long Campaign," was a showcase for a military leader we've encountered in other entries in this series: Hungarian general John Hunyadi (d. 1456). Hungary and the Ottomans reached a peace treaty in the 1420s that left the rump Serbian state as a buffer between them, but in the 1430s the Ottomans, under Sultan Murad II (d. 1451), annexed Serbia as far north as Belgrade (which at the time was actually—briefly—Hungarian property) before they had to refocus their attention on fighting the Karamanids, their biggest Anatolian rival.
The Hungarians underwent a succession crisis when Sigismund, who had been King of Hungary for 50 years, died in 1437. His successor and son in-law, Albert (technically the first Habsburg ruler of Hungary), died in 1439 without an heir—his son, the future Ladislaus V (d. 1457) was born a few months after he died. Into this breach stepped Władysław III of Poland (d. 1444, which is a bit of foreshadowing), who, with the support of most of Hungary's nobles and with John Hunyadi's help, was crowned Vladislaus I of Hungary in 1440. The infant Ladislaus V was crowned the same year and the throne remained in dispute until Varna cleared things up. For his good work, Vladislaus made Hunyadi commander of Hungarian forces in the south, and he and Vladislaus, along with Đurađ Branković, the Despot of Serbia (or whatever remained of it), resolved to take up Eugenius's call for Crusade.
Murad initially had real problems responding to this new challenge. His attention was still partly diverted to the east because of the Karamanids, and he seems to have had a hard time raising enough reliable troops to put together a new army in Europe. The Hungarians in particular were well-armed and, under Hunyadi, very well-led, deploying tactics such as the wagon fortress to great success in disrupting the Ottoman cavalry. The Crusaders won a victory at Nish (in modern Serbia) in November 1443, but then overextended themselves in the face of an Ottoman scorched earth campaign and were defeated by Murad at the Battle of Zlatitsa (in modern Bulgaria) in December. In the midst of a general retreat back to Hungarian territory to hole up for the winter, they managed to win another victory over an Ottoman force at the Battle of Kunovica (again in modern Serbia) in January 1444. The campaign having ended on a high note, the Hungarian-Polish forces declared victory and waited for the arrival of spring and the new campaigning season.
Murad, though, appears to have had other ideas—he wanted...peace (you thought I was going to say revenge, admit it). He and Vladislaus traded envoys, and in August 1444 they agreed on the Peace of Szeged. Under the treaty, Murad was obliged to restore the Despotate of Serbia, along with a portion of Serbian territory, to Branković, who was in turn obliged to make himself an Ottoman vassal. Hungary and the Ottomans agreed to 10 years of peace.
As an aside, another part of the deal involved the Hungarian governor of Wallachia (in modern Romania), who had previously entered into an alliance with the Ottomans, possibly at some strenuous Ottoman urging. His obligations under that alliance were loosened, though he promised to pay annual tribute to the Ottomans as well as to send them conscripts. He also left two of his sons, who were already in Ottoman custody (being used as leverage to keep Wallachia from joining Hunyadi's crusade), with the Ottomans as hostages. The governor's name was Vlad II Dracul, and one of the sons he sent to the Ottoman court was the future Vlad III, AKA Dracula.
Vladislaus and Hunyadi seem to have negotiated the Peace of Szeged without the slightest intention of sticking to its terms. Eugenius was very insistent that the Crusade continue after its early successes. Vladislaus wanted to keep going because the campaign was quieting support for Ladislaus and uniting the Hungarian nobility behind his claim to the throne. Hunyadi, a little more farsighted than his pals, was convinced that the time to strike the Ottomans was now, and that 10 years of peace would only allow Murad to strengthen his position. Also, Vladislaus offered to make Hunyadi King of Bulgaria if he repudiated the treaty and kept fighting, which appealed to the Hungarian warlord very much.
Part of the reason Murad desired peace became apparent when he suddenly abdicated shortly after the treaty was concluded. His successor was his very young (~12 years old) son Mehmed II (d. 1481). When Vladislaus and Hunyadi, who wanted to keep fighting anyway, found out that Murad had abdicated in favor of a child, their resolve to continue their crusade only grew. The only prominent member of the crusade who didn't want to keep fighting was Branković, who was quite happy with the terms of Szeged and therefore left the Crusader coalition. Eugenius sent a papal representative to Szeged to absolve Vladislaus of any obligation to uphold his treaty obligations, and that was that.
When the Ottomans found out that the Crusader army was approaching them again, Mehmed, at the...oh, let's say "strong urging" of his army, demanded that his father come out of retirement and command the Ottoman army in the coming campaign. Murad reluctantly agreed. The Crusader army, a combination of mostly Hungarian, Polish, Bohemian, and Wallachian troops, numbered between 20,000 and 30,000 men. They campaigned against an Ottoman army that was probably twice that size (50,000-60,000), but less than half of it was made up of the empire's reliable Janissary infantry and regular Sipahi cavalry. The Crusaders marched to Varna, on the western Black Sea coast (in modern Bulgaria), intending to meet a Venetian fleet and sail directly to Constantinople. Murad, coming from the west, managed to get to Varna before the fleet and trapped the Crusaders between his army and the Black Sea, with Lake Varna to the south and rugged terrain to the north locking the Crusaders in place.
Some of the Crusaders suggested a holding action, setting up their wagon fort to keep the Ottomans at bay until the fleet could arrive. But Vladislaus, who was only 20 and wanted to be daring and bold, and Hunyadi, who was almost 40 and probably should have known better, pushed for an attack. They assembled their forces outside of Varna on the morning of November 10, with the Ottomans assuming a more defensive position behind ditches and field works (not unlike the wagon fort, a tactic that the Janissaries were in the process of adopting for themselves).
Hungarian firepower did considerable damage to the Ottoman cavalry, and the Crusaders nearly won the day, until Vladislaus made the mistake of taking some initiative. At some point, Hunyadi left their shared center position to lead reinforcements to their left flank and told Vladislaus to stay put until he returned. But Vladislaus (again, he was 20) decided instead to lead 500 of his best knights in a cavalry charge directly at Murad's command post. As often happens in these situations, an act that could have decisively won the battle for one side (in this case, the Crusaders) wound up doing exactly the opposite, when Vladislaus was unhorsed and killed. Hunyadi tried to rally the troops to recover his body, but the demoralized army broke and ran instead.
The battle was not a one-sided rout, however. It's said that it took Murad days to figure out that he'd won, so heavy were the Ottoman casualties. But Vladislaus's death destroyed the Hungarian-Polish alliance that had fueled the Crusade, and both Poland and Hungary fell into internal discord. Vladislaus was eventually succeeded in Poland by his brother, Casimir IV, who was already the Grand Duke of Lithuania. In Hungary he was succeeded by Ladislaus—now Ladislaus V—but only after it was agreed that John Hunyadi would serve as his regent. Hunyadi took another bite at the Ottoman apple but was again decisively beaten at that Second Battle of Kosovo, which really took the final steam out of the Hungarians and quelled virtually all European resistance to the Ottomans for a time. The Hungarians would eventually resume their conflict with the Ottomans, but not until after Constantinople had fallen.