This volume includes the thirteen papers which were presented during the workshop The Reign of Heraclius: Crisis and Confrontation, which took place from 19 to 21 April 2001 at the University of Groningen. The long reign of the Byzantine emperor Heraclius (610-641) saw drastic political changes: the conquest of the eastern provinces of the empire by the Persians (603-620), Heraclius' counter-offensive and recovery of these territories (622-628), and the definitive loss of almost the whole Byzantine east in the 630s and early 640s to the Muslim Arabs. Did these historical events cause significant changes in the administrative, political, military and ecclesiastical structures and institutions of the empire? And if so, how did they affect imperial ideology and propaganda and the range of ideas concerning the empire and the emperor which circulated in the different religious communities? In the contributions presented in this book these and other questions are discussed by outstanding scholars of Byzantine history and culture, Eastern Christianity, Judaism and Islam.