In Dangerous Knowledge: Orientalism & Its Discontents, Robert Irwin highlights some of the tensions between Islam and the West that have gotten lost in the historical mist. Two struck me as particularly interesting:
-- Christopher Columbus, by sailing West, was "seeking to outflank the Islamic empires of the Ottomans, Mamluks and Safavids [in Persia]. He believed that he lived very close to the Last Days and he was inspired by knowledge that astrologers had predicted the imminent collapse of Muhammad's sect and the coming of the Antichrist."
-- The Austro-Hungarian ambassador to the Ottomans half a century later "believed that the Christian powers were wasting their time and resources in America, while Christianity's very survival was threatened by Ottoman advances in Europe ..."
And indeed, it wasn't until the Turks were defeated a hundred years later at the gates of Vienna that the tide turned against the Ottomans.