Savcı Bey
Savcı Bey was a prince who, with Andronikos, rebelled against both of their fathers, the Ottoman Sultan Murad I and the Byzantine Emperor John V Palaiologos, respectively, in the 1370s. Savcı was the youngest of Murad's three sons. The name of his mother and birth year are unknown. In Ottoman tradition, all princes were required to serve as provincial governors as a part of their training. Savcı's sanjak was Bursa, the co-capital of the empire.
Rebellion
When Ottoman Turks captured Edirne, Byzantine emperor John V Palaiologos appealed to the West for help. Instead, he was detained as a debtor in Venice. Andronikos, his son and regent in Constantinople, refused to pay the ransom for his father, and John had to give up the island Tenedos to buy his freedom. After that event, John assigned his younger son Manuel as his crown prince and accepted the suzerainty of Ottomans in 1373. Thus, when the Ottoman sultan asked for his services against some rebellions in Ottoman lands, he had to leave his capital. This absence gave Andronikos a chance to rebel.On the Ottoman side, Savcı Bey, who was the youngest of three brothers, saw that under the shadow of his older brothers, he had almost no chance to be enthroned in the future and faced a probable death under the traditional policy of fratricide in Ottoman succession.. He prepared to rebel to gain the post. While his father was occupied with suppressing the rebellions, Savcı saw his chance to revolt. Using the royal treasury under his disposal, he formed an army. The two rebellious princes, well aware of one another's interests, decided to collaborate and combined their forces.