Columbus’s major push for money occurred in the 1480s—the decade during which Isabella and Ferdinand, the eventual financiers of his voyages, declared war on Islam.

While Spain at the western end of the Mediterranean was establishing its dominion in the Americas, the Ottomans had carved out, against much tougher opponents and on a far grander scale, a vast tri-continental empire, assembling in Busbecq’s awed phrase ‘the might of the whole East’.