THERE ARE CERTAIN moments in military history that seem to capture the popular imagination so intensely that they enter the realm of myth. In Britain, they obviously include the Armada, Trafalgar, and the heroic exploits of the 'few'. Each is something more than a purely military success. Suitably mythologised, such victories come to exemplify the superiority, not just of a nation's courage and virtue, but of its destiny as well: the reassuring certitude that 'God is on our side'.

For early modern Europe, that moment was Lepanto. Fought in 1571 off the north-west coast of what is now Greece, Lepanto seemed to be the definitive turning point in a struggle against the 'Islamic threat' that had dragged on for almost a thousand years. Before Lepanto, the westward expansion of Ottoman power seemed to be inexorable. Constantinople (modern-day Istanbul) had fden