The Swedish invasion of 1655, known to Poles ever since as the 'Swedish deluge', provoked the political and military collapse of the Polish-Lithuanian Commonwealth, the second-largest state in Europe. Robert Frost examines the reasons for Poland's fall and the conduct of the war by the Polish government, and addresses the crucial question of why, despite widespread recognition of the shortcomings of the political system, subsequent attempts at reform failed. War has long been seen as crucial to the development of more effective systems of government in Europe during the seventeenth century, but studies usually concentrate on states which responded successfully to the challenges. Much can be learned from those that failed, and the paucity of English-language material on this important conflict means that After the Deluge will appeal to a broad audience among historians of Poland, Germany, Scandinavia, Russia, and early modern Europe in general.