After the battle of the Maritsa River the Ottomans greatly extended their circle of vassals, who were obliged to contribute to the Empire’s further ascent and consolidation by paying annual tributes and joining forces with the sultan in his military expeditions. They placed the urban strip and important routes along the Aegean coast under their direct rule. In 1383 the Ottomans conquered Serres and its vicinity, expanding toward Thessalonika. The monks from Mt. Athos, whose main estates were threatened, then approached them. Through Gallipoli the Turks fostered ties with their territories in Asia Minor and established relations with the major maritime powers, Venice and Genoa, which had for decades been contending bitterly over the remnants of the Byzantine Empire.
The tactics of Ottoman expansion had already been perfected. They would become involved in local conflicts at the invitation of the feuding Christian lords, familiarize themselves with the terrain, take what they wanted, and make those they aided their dependants. They undertook expeditions far from their core territory. While ruling only Thrace they sent troops to Ioánnina and Berat in Albania, and later to the Dubrovnik hinterland. A ruler’s death or family clashes were usually used as the grounds for establishing direct rule. Turkish detachments turned up in all parts of the Balkan Peninsula long before the territory of the Ottoman state approached the region.
The Ottomans had already reached Prince Lazar’s territory in 1381, when the prince’s commander Crep smashed the Turks in the battle of Dubravnica (near present-day Paraćin, in the Morava river valley). The Turkish unit had probably strayed there after some military operation in Bulgaria. A few years later, in 1386, a much more serious attack followed. Sultan Murad himself led the army that penetrated into Serbia, all the way to Pločnik in Toplica. There was no battle at the time. On that occasion, or somewhat later, the Ottomans raided Graćanica monastery, where the tower and its books were set on fire.
On the other side, the inherited hostility between King Tvrtko and the Balšićs triggered a Turkish raid into the Bileća region, where commander Shahin was defeated in August 1388. A buffer zone existed between the territories of Prince Lazar and Vuk Brankovic´ on one side, and the Ottomans on the other, consisting of the territories of Turkish vassals (the Dragaši – Dejanovic´s in the east, Vukašin’s heirs in the south). However, it was obvious that the Ottomans were closing in.
Parallel with these events, the vast Hungarian Kingdom created by Louis I Anjou (1342–82), surrounded by vassal territories on all sides, was crumbling. When King Louis died in 1382, he was succeeded by his daughter Maria, who ruled with her mother, the daughter of Bosnian Ban Stjepan II, but was met by resistance from the nobility. The ruling Anjou dynasty had relatives in southern Italy, where part of the Hungarian aristocracy sought an heir for the deceased king. Charles of Durazzo took the Hungarian throne, but soon became involved in court intrigues and was assassinated at court in 1385. The queens were accused of the assassination and open rebellion followed. The queens were captured in 1386 and their palatine (highest court dignitary), Nicolas de Gara the Elder, was murdered. A large group was formed in support of Ladislas of Naples, while Sigismund of Luxembourg, the young queen’s fiancé, tried to rally nobles loyal to the queens.
At first King Tvrtko honored the king’s successor, his cousin, and took Kotor with her approval in 1384. However, when internal rebellion erupted in Hungary he openly sided with Ladislas of Naples, along with Prince Lazar, and challenged Sigismund of Luxembourg. Tvrtko provided refuge for the rebellious Croatian noble brothers Ivaniš and Pavao Horvat, Ivaniš Paližna, and others. For a while Ivanis¡ Horvat ruled Mac¡va and Belin, Hungarian territories in Serbia south of the Sava River. Starting in 1387, Tvrtko conquered territories in Croatia and subjugated cities in Dalmatia. The city of Split resisted the longest and the deadline for its surrender was set for June 15, 1389.
King Tvrtko I and Prince Lazar were cut off from their Christian surroundings because of the conflict with the Hungarian queen and Sigismund of Luxembourg, and were joined only by the supporters of Ladislas of Naples and the Croatian rebels. Both sides of the Hungarian feud sought allies. Florence sided with the Anjou, while Sigismund of Luxembourg was supported by Venice and Duke Visconti of Milan, alleged by his contemporaries to have supplied weapons to the Turks.
Sultan Murad headed for Serbia in the early summer of 1389. He assembled an army of vassals and mercenaries, along with his own troops. By way of his vassals’ territories he reached Kosovo, from which routes led in different directions. Upon receiving news of his approach, Prince Lazar, Vuk Branković, on whose land the battle was fought, and King Tvrtko, who sent a large unit under the command of voivoda Vlatko Vuković, joined forces.
There is reliable information as to where the battle took place: part of the Kosovo Polje (Field of Blackbirds) near Priština, where Murad’s turbe (burial stone) still stands, was noted in sixteenth-century maps. The date of the battle is indubitable: St. Vitus’s Day, June 15, 1389. It is also certain that Sultan Murad was murdered and Prince Lazar was taken prisoner and slain the same day. Some Christian warriors became Turkish prisoners, and Bosnian nobles from Vlatko Vuković’s unit were still being sought in 1403 in Constantinople.
Information regarding other important details was at first contradictory. King Tvrtko reported his great victory with some casualties, but “not many,” in letters to his city of Trogir and his ally Florence. The death of the Ottoman ruler gave the Byzantines, and others all the way to France, the impression that the Christians had been victorious. According to medieval notions, holding onto the battleground was crucial in rating the outcome. The Turks remained in Kosovo for a short time, then headed east so that their new ruler Bayazid could strengthen his position. Vuk Branković, the lord of the territory, remained in place and in power, and did not immediately yield to the Turks.
Indisputable contemporary witnesses stated that contradictory versions of the battle circulated from the very beginning. Five weeks after the battle, no one in Venice knew who had succeeded Murad, and the Venetian envoy was instructed to tell anyone he found in power that the Republic had been informed, “although not clearly,” of the war between Murad and Prince Lazar, “of which different things had been said, but were not to be trusted.” Chalcocondyles, a fifteenth-century Byzantine historian, directly compared the Christians’ claims with those of the Turks, who maintained that the sultan had been killed after the battle, while inspecting the battlefield.
As time passed the tales unraveled further. The leitmotif of treason emerged on the Christian side, first linked with the Bosnian detachment and a certain Dragoslav, and then becoming focused and remaining on Vuk Branković. In the first decades following the battle, the theme emerged of the slandered knight, who went to the Turkish camp to slay Sultan Murad. Under the influence of epic tales of chivalry, Murad’s assassin and Lazar’s traitor were linked together, both becoming the prince’s sons-in-law. In the late fifteenth century the topic of the prince’s dinner and Lazar’s toast was well known. An entire collection of epic poetry was created containing many picturesque details, very far from reality.
The general view of the battle and its consequences was also far from reality. The battle of Kosovo was not a Crusade, nor was it the defense of Christianity, because the hinterland was hostile. At the time of the battle, Sigismund of Luxembourg had started an expedition against the Bosnian ruler. Prince Lazar had managed to achieve peace, with the mediation of his son-in-law Nicolas Gara the Younger, while Tvrtko remained at war with King Sigismund.
The idea that the “fall of the Serbian Empire” took place at the battle of Kosovo is fundamentally wrong, because the state continued to exist for a further seven decades and experienced economic and cultural revival. According to folklore traditions, the battle of Kosovo set off migrations and ruptured the development of clans and families. Of all Serbian historical events, the battle of Kosovo has been the most popular episode, deeply engraved in the national consciousness. It served as an inspiration for courageous deeds and sacrifices up to the twentieth century, and was widely used in condemning and stigmatizing treason.