It’s a confusing feature of modern Europe that the historical principality of “Moldavia” is more a precursor to modern Romania than modern Moldova, even though Moldova goes back to the former Soviet Republic of Moldavia. It’s a fact that more of historical Moldavia is now in Romania than in Moldova. For example, the Moldova River runs entirely through modern Romania, not once touching (nor coming particularly close to) the territory of the country named for it. Ethnically there’s no major distinction between the Moldovans and Romanians. Moldvans speak Romanian, though during the Soviet period they called it “Moldavian” and it’s still referred to as “Moldovan” in some quarters. It’s messy and I have no interest in hashing out Eastern European ethnic and border issues here, but I mention this only to explain why Stephen III of Moldavia (d. 1504) is today known as a national hero in Romania, and why the battle we’re talking about today, pitting Stephen’s Moldavians against the Ottomans, took place in an area that’s in Romania today.
Stephen III, who ruled Moldavia from 1457 until his death and is known as “Stephen the Great and Holy” if you’re into that sort of thing, is said to have fought dozens of battles against all comers during his reign, and only lost two of them. He defended the generally outsized and outmanned Moldavia against every surrounding power that tried to quash its autonomy or threaten its prosperity: Hungary, Poland, the Mongols, and, most especially, the Ottomans. At Vaslui he became one of the first European rulers to take on and defeat the Ottomans after the fall of Constantinople–although, struggling to fend off threats from both the Ottomans and the Poles, he eventually wound up paying tribute to Constantinople anyway, in exchange for guarantees of Ottoman non-aggression.
The immediate cause of the conflict was a dispute over neighboring Wallachia. Ottoman Sultan Mehmed the Conqueror thought Wallachia was in good hands under his clients, Radu the Handsome (Dracula’s brother, and Stephen’s cousin) and then later Basarab Laiotă the Old. Stephen disagreed. Really, the fight was over the Black Sea coastal region of Bessarabia, and specifically the fortresses of Chilia (modern Kiliya, in Ukraine)–which was at one time Wallachian, then Moldavian, then Hungarian (Transylvanian, technically), then Wallachian again–and Akkerman (modern Bilhorod-Dnistrovskyi, also in Ukraine). Stephen at one point allied with the Ottomans to get Bessarabia back from Wallachia, then turned on the Ottomans when Wallachia became their vassal and Bessarabia thus came under their control. I get a headache trying to parse this stuff.
The region was important, obviously, or else it wouldn’t have been so highly prized. For one thing, there was its commercial value, sitting as it did along the Black Sea coast. Chilia was especially important, because it controlled the point where the Danube River empties into the sea. Strategically, Ottoman control of Bessarabia opened all of Moldavia to their armies, and Moldavia in turn was an ideal staging point for an invasion of Hungary and Poland–and, if you were going in the opposite direction, the Ottoman Empire. For both offensive and defensive reasons, then, Mehmed wanted Moldavia–or at least wanted Bessarabia, so that he always had the option of easily invading Moldavia.
Stephen kept trying to put his own candidate in charge of Wallachia. He had an on again, off again alliance with Dracula, or Vlad the Impaler if you like. Dracula had helped Stephen win the Moldavian throne, but they then fell out, over control of Chilia. But Radu supported the Ottomans–so much so that there’s been speculation he converted to Islam during his time as an Ottoman hostage, though accounts of his conversion were probably stuck into the historical record after the fact to defame him and explain his chumminess with the Ottomans–in exchange for their help in toppling Vlad, which made him unambiguously Stephen’s enemy. Stephen put Basarab Laiotă on the Wallachian throne in Radu’s place twice, in 1473 and again in 1474, but after the second time Laiotă stabbed Stephen in the back and pledged his loyalty to the Ottomans.
So Stephen invaded Wallachia yet again in October 1474, and forced Laiotă to flee. Mehmed demanded that Stephen knock it off with the repeated invasions, whereupon Stephen told Mehmed, politely I’m sure, to go suck an egg. So Mehmed ordered one of his generals, Hadım Suleiman Pasha, who was busy besieging the city of Shkodër (in modern Albania), to complete that siege post haste and then march his men into Moldavia to deal with Stephen. This was a serious mistake. Suleiman Pasha’s men had already been in the field for months, and now they had to make a winter march all the way across the Balkans on this new mission. They would be in no condition to fight once they arrived.
The Ottomans outnumbered the Moldavians considerably, but how considerably isn’t entirely clear. Stephen probably had around 40,000 men, but as many as 3/4 of them were poorly armed, poorly trained peasant conscripts. Suleiman Pasha probably had over 100,000 men at his command, but some portion of this was also conscripts, picked up along the way from Shkodër, as well as some 17,000 or so Wallachians, who as we’ll see turned out to be less than reliable. Stephen elected to tax the already struggling Ottoman forces by retreating north and carrying out a scorched earth campaign behind him, forcing his enemy to march even further without much ability to resupply itself. He finally turned and met the Ottoman army outside Vaslui, in an area Stephen knew well but Suleiman didn’t know at all.
This was another Ottoman mistake, and it proved to be insurmountable. The battlefield Stephen chose was a valley, and on the heights and in the forests around it he stationed archers, artillery, and reserves to strike the Ottomans from multiple angles. He used his infantry and light cavalry to lure Suleiman’s men into the trap. When the Ottoman commander committed reserves into the valley in an attempt to relieve the men who were being pounded by all that cannon and arrow fire, Stephen ordered an all-out attack from three sides on the confused and bedraggled Ottoman force. The Ottomans broke and ran, and Stephen’s army spent the next couple of days chasing them back to imperial territory. Somewhat hilariously, Laiotă’s Wallachians refused to fight with the Ottomans, then helped harass their retreat through Wallachia.
Stephen, who had asked other Christian kingdoms for aid before the battle and was given nothing more than a handful of Polish and Hungarian fighters, now sent another appeal for aid along with some of his Ottoman prisoners to Poland, Hungary, and Rome. Thanks to his great victory at Vaslui, this time Stephen’s appeal was met with…pretty much nothing, just like before. Mehmed, meanwhile, was furious, as you might imagine, and made vengeance on Stephen his top priority.
After Stephen drove off a raid into Moldavia by the Ottomans’ Crimean Tatar vassals, Mehmed sent a ~150,000 man army north in 1476 that ultimately defeated Stephen (albeit at considerable cost) at the Battle of Valea Albă in July. However, the Ottomans weren’t able to capitalize on their victory, as a combination of disease, Stephen’s harassment, and the arrival of a new army raised by Dracula (who was still contesting Wallachia with Laiotă) forced them to retreat (Vlad then briefly put himself back on the throne of Wallachia, before the Ottomans killed him in December 1476). The Ottomans eventually did capture Chilia and Akkerman in 1484. Moldavia proper remained out of their hands, but Stephen wound up agreeing to accept Ottoman vassalhood and begin paying tribute to Constantinople.