Gennadius II, a staunch antagonist of the West because of the Sack of Constantinople committed by the Western Catholics and theological controversies between the two Churches, had been enthroned the Ecumenical Patriarch of Constantinople-New Rome with all the ceremonial elements and ethnarch (or "milletbashi") status by the Sultan himself in 1454. In turn, Gennadius II formally recognized Mehmed as successor to the throne. Mehmed also had a blood lineage to the Byzantine Imperial family; his predecessor, Sultan Orhan I had married a Byzantine princess, and Mehmed may have claimed descent from John Tzelepes Komnenos. Ottoman sultans were not the only rulers to claim such a title, as there was the Holy Roman Empire in Western Europe, whose emperor, Frederick III, traced his titular lineage from Charlemagne who obtained the title of Roman Emperor when he was crowned by Pope Leo III in 800, although he was never recognized as such by the Byzantine Empire.