The article focuses on the issue of Byzantines’ voluntary transition into the authority of Ottoman Turks as regarded by Byzantine writers. Referring to a number of works of intellectuals of the late 14th — early 15th century, the author identifies the reasons and motives that forced the Greek population to prefer the Ottoman rule. Contemporaries noted the plight of the Greeks in the besieged cities, the difficult economic situation and public dissatisfaction with the Byzantine government, which was unable to provide proper defense. Information given by Simeon of Thessalonica about the history of Thessaloniki in 1382–1429 allows recreating the picture of the Greek population’s life in the times of sieges, and tells about changes of government in the city, its political and economic instability. The author concludes that the main motive of the Byzantines to move to the side of the invaders was to secure a stable and peaceful life which the Byzantine administration being unable to repel the Turks proved unable to provide, as well as previous experience of Turkish rule to ensure the loyalty of the Greeks.