The Antonine Constitution is nowadays regarded as one of the most globally important constitutional documents in history. In 2017, it was formally inscribed into the UNESCO Memory of the World Register, placing it alongside other charters such as Magna Carta, the Golden Bull of Emperor Charles IV, and the Declaration of Human and Civil Rights introduced by the French National assembly in 1789. It is, with good reason, seen as the genesis for many later concepts of citizenship in Europe and beyond. But the Antonine Constitution remains apart from its eventual successors. It was not predicated on any singular European centre or national statute: it established a uniquely transnational network of citizens, whose own local and customary rights were simultaneously preserved.

The universal significance of the Antonine Constitution, however, rests somewhat uncomfortably against the image of the Roman emperor responsible for its promulgation. Caracalla is best known for his allegedly murderous rage, ordering the assassination of his own brother to secure his grasp on the imperial throne, and accused of laying waste to the city of Alexandria with little provocation. The apparently progressive and avant-garde Constitutio Antoniniana seems a bizarre and almost incredible act on the part of an autocratic ruler whose self-identity was characterised predominantly by militaristic iconography and a message that his regime was divinely sanctioned. In this book, I aim to address this paradox, and to shed some light on the emperor’s rationale for introducing such a revolutionary constitutional change.

This monograph would not have been possible without the input and assistance of many people. The doctoral thesis that forms the core of this publication was generously sponsored by the Kerr-Fry fund in Edinburgh. Their willingness to support my postgraduate research, from Masters onwards, was gratefully received. Indeed, it undoubtedly removed many of the worst financial anxieties that are an unfortunate component of the modern PhD experience for the majority.

The School of History, Classics and Archaeology at the University of Edinburgh has presented me with a stimulating and supportive environment since my earliest days as an undergraduate in 2003. As a first-generation university attendee, I had little familiarity with the world of academia, but the knowledge, enthusiasm and opportunity presented to me by various members of faculty were significant enough to help me overcome most of my fears, and set out towards a career in the discipline. Foremost among these is Sandra Bingham, whose passionate belief in my project and abilities as a scholar have been a constant source of confidence and motivation. With her support, I felt able to write on the subjects that I wanted to, rather than conforming to others’ assessments of the field. She has been instrumental in making me the classicist that I am today. Lucy Grig has also been an important influence in my development. Her readiness to challenge and play devil’s advocate with my ideas has always pushed me to test my attachment to any hypothesis that I have pursued. I hope that this book, the summation of our years spent working together, makes them as happy as it does me.

Many others have read my work and have offered helpful thoughts, comments and suggestions. I am grateful to Olivier Hekster for his continual assistance in refining my doctoral thesis into this monograph. Our first meeting was during my final PhD defence, in which he acted as an examiner. I confess to being more than a little awestruck and intimidated by his fierce intellect, initially, but I could not have asked for a better champion for my work thereafter. He has been a continually positive correspondent, and a driving force in my path towards a first book. Similarly, Andrew Erskine has been a welcome adviser in this process, whose own wealth of experience has been an invaluable source of information. I have been fortunate to work alongside a number of talented classicists, both during my PhD and beyond. Amy Bratton, Nicole Cleary, Raphaëla Dubreuil, Juan Lewis, Fiona Mowat, Peter Morton, Katie Thostenson and Cas Valachova all deserve recognition for reading parts of my work as it developed, and for their continued friendship and camaraderie. Special mention goes to David Greenwood, for his dry wit and his sense of perspective; and Belinda Washington, for her unerring ability to motivate me and make me laugh, even at my lowest ebb.

Without the love and support of those above and following, I doubt that I could have completed this book. I am grateful to my parents, Rose and Alexander, for nurturing my love of learning, and for working relentlessly in order that I might pursue my goals and attend university; to Darren Maley, for two decades’ worth of stimulating conversations, and for his unfailing friendship; and to my wife Rachael, for being the part of me that I was missing until I met her. It is nearly impossible to articulate everything that I owe to Rachael. Her selfless devotion to sharing my aspirations made it possible for me to make the very most of my time as a doctoral student. More generally, though, my life would be inestimably poorer for her absence. She is and ever will be my muse and inspiration.