In 1683, two empires – the Ottoman, based in Constantinople, and the Habsburg dynasty in Vienna – came face to face in the culmination of a 250-year power struggle: the Great Siege of Vienna. Within the city walls the choice of resistance over surrender to the largest army ever assembled by the Turks created an all-or-nothing scenario: every last survivor would be enslaved or ruthlessly slaughtered. Both sides remained resolute, sustained by hatred of their age-old enemy, certain that their victory would be won by the grace of God. Eastern invaders had always threatened the West, but the memory of the Turks, to whom the West’s ancient and deep fear of the East is viscerally attached, remains vivid and powerful. Long before their 1453 conquest of Constantinople, the Turks had raised the art of war to heights not seen since the Roman Empire. Although their best recorded and most infamous attack, the 1683 siege was the historical culmination, not the extent, of the Turks’ sustained attempt to march westwards and finally obtain the city they had long called ‘The Golden Apple’. Their defeat was to mark the beginning of the decline of the Ottoman Empire.

Scholars have long argued over whether the 1648 Peace of Westphalia, which ended more than a century of religious conflict arising from the Protestant Reformations, inaugurated the modern sovereign-state system. But they largely ignore a more fundamental question: why did the emergence of new forms of religious heterodoxy during the Reformations spark such violent upheaval and nearly topple the old political order? In this book, Daniel Nexon demonstrates that the answer lies in understanding how the mobilization of transnational religious movements intersects with--and can destabilize--imperial forms of rule. Taking a fresh look at the pivotal events of the sixteenth and seventeenth centuries--including the Schmalkaldic War, the Dutch Revolt, and the Thirty Years' War--Nexon argues that early modern "composite" political communities had more in common with empires than with modern states, and introduces a theory of imperial dynamics that explains how religious movements altered Europe's balance of power. He shows how the Reformations gave rise to crosscutting religious networks that undermined the ability of early modern European rulers to divide and contain local resistance to their authority. In doing so, the Reformations produced a series of crises in the European order and crippled the Habsburg bid for hegemony.