Selim I

The war Selim fought against Shah Ismail in 1514 was unlike the ordinary competition between Muslim dynasties, because the Safavid movement made claims about its leader that his followers took in a religious sense, and because the Qizilbash who followed him were spread through Anatolia, inside Ottoman territory, and looked south east for their loyalty. The campaign therefore needed a justification for making war on Muslims, and it was supplied by scholars whose opinions declared the enemy outside the community. The battle at Chaldiran was won by Ottoman artillery and firearms against cavalry, and it stopped the Safavid advance westward for good.

The consequence was a boundary that was doctrinal as much as territorial. Before the sixteenth century the distinction between Sunni and Shia had not generally been a matter of which state a person lived in. Afterwards it increasingly was, as one empire consolidated a Twelver Shia establishment and the other a Sunni one, each defining itself partly against the other, and populations were displaced or repositioned accordingly. That border between the two, drawn through eastern Anatolia and Mesopotamia by a series of wars beginning here, has proved one of the most durable religious frontiers anywhere.

The campaigns of 1516 and 1517 took Syria, Egypt and, with them, the protection of Mecca and Medina, when the sharif of Mecca sent the keys of the sanctuary and acknowledged Ottoman authority. The title that mattered afterwards was Servant of the Two Noble Sanctuaries, which is a claim about duty rather than about doctrine: responsibility for the pilgrimage routes, the water supply, the security of pilgrims and the upkeep of the two mosques. Ottoman sultans took that obligation seriously for four centuries and spent enormous sums on it.

The caliphate is a separate and later story. There is a well known tradition that the last Abbasid caliph, living under Mamluk protection in Cairo, formally transferred the office to Selim, and modern scholarship generally treats that account as a construction of a much later period rather than a record of 1517. The Ottoman claim to the caliphal title became prominent when it was useful, in the treaty diplomacy of the later eighteenth century, as a way of asserting spiritual standing over Muslims who had passed under other rulers. It was still being asserted in that form in the nineteenth century, and it was abolished by the Turkish Republic in 1924, an act whose consequences are still being worked out.