The crude picture depicts the nineteenth century as an epoch that perpetuated anarchy and in which states dwelled in a “Hobbesian dilemma”, a war of all against all, that legitimised the nations’ free right to wage war (liberum ius ad bellum); that came to an end when war-torn Europe embraced the Kellogg-Briand Pact of 1928 in the aftermath of the First World War. The formation of the League of Nations was a “Big Bang Moment” in the history of international legal thought; for the first time in human history it outlawed the use of force, and created a catalyst effect on the development of international order and the international rule of law by making the prohibition of use of force the kind of a Grundnorm in modern international order. In A Century of Anarchy: War, Normativity, and the Birth of Modern International Order, Hendrik Simon challenges this omnipresent narrative in a dialectical manner, raising questions about the war that prevailed in the nineteenth century. Unveiling the ephemeral importance of the nature of warfare derived from discursive moments in history, Simon opens up a new way of looking at nineteenth-century history as an interplay between war and order. In his own words, “the way we remember the nineteenth-century discourse on war and international order touches on essential questions of the emerging modern legal theory and its sources in the so-called ‘positivist’ nineteenth century” (p. 67).

In his acute introduction that systematically questions the ubiquitous nature of war and normativity in the modern international order, Simon highlights the corpus of literature that enthroned the nineteenth century as an era of anarchy. Simon argues that leading jurists in the twentieth century, such as Hans Wehberg, made no serious attempt to identify how the nineteenth century shunned anarchy through various means. On the contrary, Wehberg’s polemic on the nineteenth century reverberates to this day. The closer inspection that Simon draws in his introduction reveals how both liberal and realist narratives centre the state’s free right to wage war in the nineteenth century. For political realists, the alleged free right to use force in the nineteenth century expresses the eternal “law of the strongest” in international relations in an almost ideal-typical way. For liberals, in contrast, the nineteenth-century free right to go to war represents the pre-modern antithesis to their narrative of international legal progress in the twentieth century. Simon denies this claim as a fallacy. He builds his contentions about the normative status of the war in the nineteenth century, first by constructing an alternative narrative to the notion of a free right to go to war; one which indicates that neither nineteenth-century state practice nor its leading scholars admitted the universality of the liberum ius ad bellum. Paradoxically, military violence was invoked as a necessity throughout the century, especially after the Napoleonic Wars. Second, Simon examines the historical roots of the liberum ius ad bellum from a history of science perspective. This adopts a novel way of analysing how political trajectories in the late nineteenth century, in particular the unification of Germany, solidified the idea of the free right to go to war. Finally, Simon questions the tapestry of modern historiography of war and international order that has been built on the surface of nineteenth-century narrative.

Simon’s scholarship shines through the pages as he analyzes the historical evolution of the doctrine of liberum ius ad bellum from the Greek Roman antiquity onwards. This includes discussion of the concept of just war (bellum iustum), regarded as the crowning achievement of the ius gentium in the medieval era. Simon points out the flows of the concept of just war which gradually transformed into liberum ius ad bellum, mainly its ambiguity and lack of a reliable definition. Simon also traces how revolutionary moments in Europe set the stage for the idea of modern warfare. The French revolutionaries tried to secularise and modernise just war in a novel combination of natural law and political radicalism in order to distance themselves from the old international legal order. Simon unveils how the revolutionary and Napoleonic period gave birth to modern legitimation of war; in his own words, “it was, at the same time, the link between pre-modern and modern conceptions of war, law(making), and international order” (p. 108). Having given credit to the French Revolution as a moment that left an indispensable mark on modern thought on war, normativity and use of force, Simon pays attention to the intellectual contributions of Kant and Clausewitz as pioneers of modern war discourse. Their insights augmented the dichotomy between political and legal primacy.

In Chapter 4, entitled “Birth of an International Order”, Simon discusses the significant political shifts in Europe following the battle of Waterloo. He highlights how the Congress of Vienna in 1815 aimed to establish an era of peace and argues that the consensus reached at the Congress among participating European states marked a pivotal moment for the formation of an international order. Unfortunately, this crucial development has often been overlooked by historians of international law, who tend to focus primarily on the last decade of the nineteenth century. It was after Vienna that legal prohibition of war swiftly began to evolve as a rising norm despite the absence of well-developed treaties as supportive tools. Simon’s analysis, filled with many historical references, affirms the imperative of the Congress of Vienna as an instrument that helped to forge the discourse of international order. To some degree, the Concert of Europe was a platform for the European monarchs to safeguard their authority by suppressing the revolutionary movements across the continent, which transformed the Vienna Order into an institution that justified the use of force in certain circumstances.

According to Simon, the Vienna Order was a classic example of a Janus-faced scenario. It was a normative frame of reference for the pacification of international relations through trust, solidarity and normativity among the Great Powers; at the same time, it was a “legalised hegemony” to enforce the Great Powers’ norms and interests. Parallel to discussing the development of international order against the use of force under the Vienna Consensus, Simon draws attention to the early attitude of Europe towards non-European powers, which was a conspicuous illustration of the earliest development of international law under Eurocentrism. For instance, major European powers shared a condescending view of Ottoman power as a semi-civilised entity located beyond the scope of Ius Publicum Europaeum. Simon argues that the popular notion of the Kellogg-Briand Pact is rendered redundant by carefully tracing its nineteenth-century antecedents. In subsequent chapters, Simon examines how statesmen such as Bismarck and Cavour justified the use of force through the lens of realpolitik, and highlights the role of newly emerged European powers.

The central idea regarding the absence of a prohibition on the use of force in the nineteenth century, which was championed by Carl Schmitt, emphasised the supremacy of state sovereignty. In this context, the use of force did not require justification. Following the Clausewitzian perspective, war was viewed as a continuation of politics by other means, which reinforced the widely acknowledged narrative of nineteenth-century anarchism. The reader of Simon’s work will know the myth behind this discourse. Simon presents a comprehensive picture of German military thought which developed after the unification of Germany in 1871 and resulted in the glorification of the idea of war as a necessary tool for the preservation of empire. Smitten by Clausewitz’s paradoxical trinity (passion, reason and chance), which was akin to a dialectical analysis of war, German statecraft ignored the existing rules on international order as an exception for the empire. However, this did not entirely enable the imperial rulers in Germany to escape from the normative order adopted by the European powers at the Congress of Vienna in 1815. Simon argues that German leadership was aware of the principles and norms of the international order, at least ostensibly and for the purpose of justifying its power as legitimate internationally.

The flow of the book, which astutely explores the roots of the myth that painted the nineteenth century as the epoch of anarchy, is somewhat similar to the earlier work of David Kennedy, who pointed out that liberal lawyers of the 1920s constructed a dark and anarchic image of the nineteenth century to portray the League of Nations and its norms as particularly progressive (D. Kennedy, “International Law and the Nineteenth Century: History of an Illusion” (1996) 65 Nordic Journal of International Law 385). Although there are similarities in their thoughts, it is not reasonable to claim that Simon replicates Kennedy’s position. Simon’s work is rich with original ideas, particularly in its academic exploration of how the turbulent period following the French Revolution and the Coalition Wars heightened the need for a solid framework regarding the legitimacy of war. Simon’s analysis makes clear that both Kant and Clausewitz established a bifurcation on the modern concept of the legitimacy of war. After having looked at how Clausewitz added primacy of political means to the legitimacy of war, Simon analyses how the Kantian position on international law, advocating for perpetual peace, shaped the direction of the international order, especially at the Congress of Vienna which limited the scope of legitimate reasons for violence.

Hendrik Simon’s A Century of Anarchy: War, Normativity, and the Birth of Modern International Order is a brilliant analysis that weaves together a compelling narrative based on findings from European history. This narrative challenges the long-held academic belief that liberum ius ad bellum was a freely exercised right by European nations in the nineteenth century. While Simon deserves praise for his intriguing work, it has a significant flaw: he excludes non-European history from the discussion on the development of the modern international order. Simon overlooks how European colonial powers vigorously exercised their perceived right to wage war in colonised territories where the native inhabitants were not considered to have attained a civilised status. Thus, the legitimacy of violence was a licence for European colonial powers, regardless of its prohibition after the Congress of Vienna; in this way, international law evolved to be the Gentle Civilizer of Nations. However, this shortcoming does not mar the far-reaching contribution of Simon’s scholarship with its twin qualities of originality and clarity.