In fact, the rise of fanaticism can be traced directly to the end of the caliphate in 1923. Kemal Ataturk, the Turkish hero of Gallipoli, buried the Ottoman Empire with little ceremony when he took power after the First World War, abolishing all its symbols, from Arabic script and the veil to the fez. The caliphate was, in his nationalist, secularising view, just another antiquated hangover from the long, humiliating decline of what had been known for nearly a century as "the sick man of Europe".
But the caliphate's abolition had an impact far beyond the borders of Turkey: it removed a central point of reference for Muslims everywhere. The poet WB Yeats was not thinking of Islam when he wrote his famous lines: "Things fall apart/ the centre cannot hold," but that was the effect of the caliphate's downfall.