Who has the right to wage war? The answer to this question constitutes one of the most fundamental organizing principles of any international order. Under contemporary international humanitarian law, this right is essentially restricted to sovereign states. It has been conventionally assumed that this arrangement derives from the ideas of the late-sixteenth century jurist Alberico Gentili. Claire Vergerio argues that this story is a myth, invented in the late 1800s by a group of prominent international lawyers who crafted what would become the contemporary laws of war. These lawyers reinterpreted Gentili's writings on war after centuries of marginal interest, and this revival was deeply intertwined with a project of making the modern sovereign state the sole subject of international law. By uncovering the genesis and diffusion of this narrative, Vergerio calls for a profound reassessment of when and with what consequences war became the exclusive prerogative of sovereign states.

Winner, 2023 ISA Francesco Guicciardini Prize for Best Book in Historical International Relations, International Studies Association

‘Claire Vergerio’s book is a tour de force. She reveals the deep history of a myth upon which so much of the field of international relations is born, and from it our understandings of sovereignty, war, and the leap to the modern world. By exposing the readings and cult of Alberico Gentili as the source of this vision, she clears the way to explore different orders for our times, alternatives with their own narratives.’

Jeremy I. Adelman - Princeton University

‘Claire Vergerio has written a superb account of the ideas and reception of the important jurist Alberico Gentli. Spanning centuries, her acute analysis traces the development of his thought, and the impact it had on a variety of debates and discourses about the morality and laws of war, from the early modern era to the twentieth century. Theoretically innovative and historically rich, War, States and International Order is an impressive work of scholarship.’

Duncan Bell - University of Cambridge

‘Its remarkable erudition and meticulous attention to detail make War, States, and International Order an outstanding piece of scholarship, situated where the concerns of legal history, history of political thought and international relations intersect.’

Jens Bartelson Source: Perspectives on Politics

‘Claire Vergerio’s remarkable book convincingly reconstructs why and how Alberico Gentili has become from the 1870s the pillar of the foundational myth of the laws of war. … Vergerio’s book is a useful guide for blazing, we hope, further trails towards a broader understanding of the legal right to use force in the current international order.’

Luigi Lacchè Source: Journal of the History of International Law / Revue d'histoire du droit international

‘The book is a very solid work of intellectual history … International lawyers will gain new insights on the canonical ideas of the field, and the book should also interest students of international relations for the light it sheds on that discipline’s own origins.’

Will Smiley Source: Political Science Quarterly

‘This book is a commendable achievement that contributes to a deeper understanding of the origins of international legal norms. This text will certainly be essential reading for those interested in the history of international law, early modern political thought, and the value of merging contextual and reception theory.’

Matthew Cleary Source: Grotiana