The Ottoman defeat at the Battle of Ankara in July 1402 and the subsequent disappearance of Sultan Bayezid I presented an opportunity for the Serbian magnates to take advantage of the turmoil and wield more autonomy in their political decision making. Having fought on the side of the Ottomans, they returned from Ankara through Byzantine-held territory. The new political landscape made for closer Byzantine–Serbian cooperation, and in August 1402, at Constantinople, Byzantine Emperor Manuel II Palaiologos awarded one of the Serbian magnates, Stefan Lazarević, the very high title of Despot. Second only to imperial dignity, the title brought the bearer great honor. From Constantinople, Lazarević was hoping to pave the way for an independent Serbia. While staying there, he came to quarrel with another Serbian magnate, his nephew Đurađ Branković. Although the reasons remain unknown, fifteenth- and sixteenth-century Ragusan chronicler Mavro Orbini attributes the quarrel to Lazarević's suspicions that Branković wanted to join forces with Süleyman Çelebi, Bayezid's oldest son, who held power in Rumelia. The historian Dimitris Kastritsis notes that the rivalry between Branković and Lazarević dated back to the time of Bayezid, who had expelled Branković's father from his lands and granted some of them to Lazarević. Although Lazarević aimed to induce Emperor John VII to imprison Branković, it is not certain if he succeeded. In 1402, Lazarević ordered Branković imprisoned, but the latter spent little time in captivity, as he was freed with the help of a friend in September of that year. Branković immediately went to Süleyman Çelebi, whom he asked for troops to fight Lazarević.
