Field-armies
Serbian armies were composed of lance-armed light and heavy cavalry, plus infantry (armed with spears, axes, and above all bows and, later, crossbows) and a baggage-train (komora) manned by shepherds and cattlemen referred to as Vlachs, probably indicating that they were Pindus Vlachs and Albanians, and perhaps Wallachians too. Most of their armies tended to be small because of the difficulties involved in supplying them in the field, and on the whole they could probably raise only about 12,000 men in the late-Lath century, the army at Kosovo probably numbering at most 20-25,000 men even including allied contingents. The majority were cavalry. Dushan was said to have raised around 80,000 men for the Invasion of Bosnia in 1350 although the largest Serbian army on record in this period was that raised by Dušan in 1355 for his proposed attack on Constantinople, which numbered 85,000 men according to later Ragusan chronicles. Modern authorities, however, give this figure little credence.
After the Battle of Marica in 1371, Ottoman suzerainty was accepted by the Serbian rulers in Macedonia: King Marko (Vukašin Mrnjavčević's son), Konstantin Dragaš, and Radoslav Hlapen. By 1388, Djuradj Stracimirović Balšić, the lord of Zeta, also became an Ottoman vassal. Stefan Lazarević and Vuk Branković accepted Ottoman suzerainty in 1390 and 1392, respectively. Lazarević ceased to be an Ottoman vassal in 1402, when he became a despot and created the Serbian Despotate. According to most authorities it was from 1390 on that the despot of Serbia was obliged to pay an annual tribute of 1,000 lbs of gold and to provide the sultan with a contingent of 1,000 cavalry when called upon. Finlay and Creasy, however, maintained that it was 'the treaty of 1376' that first imposed this obligation, while Gibbons says 1386; certainly there were Serbs as well as Bulgarians and Byzantines in the Ottoman army that fought against the Karamanli Turks in Anatolia in 1387 (the Serbs being promised booty in return for their services). Finlay says in one of his books that Sultan Beyazid actually demanded the service of the same number of Serbians as the Byzantines had called for after Manuel's subjugation of Serbia in 1150, i.e. 2,000 to armies serving in Europe and 500 to armies serving in Asia; but in another book he says that the figure was only 'subsequently increased to 2,000 men' when Beyazid was gathering his forces to confront Tamerlane in 1402. Bertrandon de la Brocquière, in his 'Travels' of 1432-33, recorded of the despot of Serbia that 'every time the sultan sends him his orders, he is obliged to furnish him with 800 or 1,000 horse, under the command of his second son.' Elsewhere he adds how he had heard that 'in the most recent army from Greece, there were 3,000 Serbian horse, which the despot of the province had sent under the command of one of his sons. It was with great regret that these people came to serve him, but they dared not refuse.' (This army was probably that which campaigned against Albania in 1430-31, in which Serbs are known to have been present.) Konstantin Mihailović reports that when the treaty with Serbia was renewed under Mehmed II the obligatory tribute was set at 1,500 lbs of gold and a contingent of 1,500 cavalry.
Amongst the battles in which Serbs fought for their Ottoman masters were Rovine, against the Wallachians and Bulgarians, in 1395; Nikopolis in 1396, where apparently their contingent comprised 5,000 cavalry; and Ankara in 1402, where Doukas says there were 5,000 'encased in black armor' and Chalkokondyles that there were an unlikely 10,000 (though the Ottoman chronicler al-Anwari says that there were 10,000 Serbs and Wallachians altogether). George Branković even supplied an unwilling contingent (of 1,500 horses under the voivode Jaksa Brezicic according to Mihailović) for the final siege of Constantinople in 1453, plus some silver-miners from Novo Brdo whom Sultan Mehmed employed as sappers. In 1473 on Aug. 11 the army that marched against Uzun Hasan which resulted in an Ottoman victory in The battle of Otlukbeli included 'many Christians - Greeks, Albanians and Serbians - in their number.'
Read more about this topic: Medieval Serbian Army