Suleiman the Magnificent
At the time of Suleiman's death, the Ottoman Empire was one of the world's foremost powers. Suleiman's conquests had brought under the control of the Empire major Muslim cities (such as Baghdad), many Balkan provinces (reaching present day Croatia and Hungary), and most of North Africa. His expansion into Europe had given the Ottoman Turks a powerful presence in the European balance of power. Indeed, such was the perceived threat of the Ottoman Empire under the reign of Suleiman that Austria's ambassador Busbecq warned of Europe's imminent conquest: "On [the Turks'] side are the resources of a mighty empire, strength unimpaired, habituation to victory, endurance of toil, unity, discipline, frugality and watchfulness ... Can we doubt what the result will be? ... When the Turks have settled with Persia, they will fly at our throats supported by the might of the whole East; how unprepared we are I dare not say." Suleiman's legacy was not, however, merely in the military field. The French traveler Jean de Thévenot bears witness a century later to the "strong agricultural base of the country, the well being of the peasantry, the abundance of staple foods and the pre-eminence of organization in Suleiman's government".
Caliphate
The caliphate was claimed by the sultans of the Ottoman Empire beginning with Murad I (reigned 1362 to 1389), while recognising no authority on the part of the Abbasid caliphs of the Mamluk-ruled Cairo. Hence the seat of the caliphate moved to the Ottoman capital of Edirne. In 1453, after Mehmed the Conqueror's conquest of Constantinople, the seat of the Ottomans moved to Constantinople, present-day Istanbul. In 1517, the Ottoman sultan Selim I defeated and annexed the Mamluk Sultanate of Cairo into his empire. Through conquering and unifying Muslim lands, Selim I became the defender of the Holy Cities of Mecca and Medina, which further strengthened the Ottoman claim to the caliphate in the Muslim world. Ottomans gradually came to be viewed as the "de facto" leaders and representatives of the Islamic world. However, the earlier Ottoman caliphs did not officially bear the title of caliph in their documents of state, inscriptions, or coinage. It was only in the late eighteenth century that the claim to the caliphate was discovered by the sultans to have a practical use, since it allowed them to counter Russian claims to protect Ottoman Christians with their own claim to protect Muslims under Russian rule.