The myth of liberum ius ad bellum : justifying war in 19th-century legal theory and political practice

The proposition of so-called liberum ius ad bellum claims that European states in the 19th century were no longer bound by the moral criteria of just war (bellum iustum) but that they held a sovereign right to go to war. This thesis is widely accepted among scholars of the history of international law and international relations alike. Nevertheless, the realist perspective on international relations was challenged in 19th-century international legal discourse. Several contemporary international lawyers were in favour of the legalization of international relations in order to legally ban unilateral war. Not much attention has so far been paid to the controversial debate on liberum ius ad bellum, which appears particularly in late 19th-century legal treatises. In the present article, this dispute will be analysed by comparing different normative justifications and criticism of war in 19th-century international legal doctrine. As will be shown, by confronting legal doctrine with contemporary state practice, the narrative of liberum ius ad bellum constitutes a myth in the history of

The notion of a Right to go to war, cannot be properly conceived as an element in the Right of Nations.For it would be equivalent to a Right to determine what is just not by universal external laws limiting the freedom of every individual alike, but through one-sided maxims that operate by means of force.
-Immanuel Kant 1 [W]ar is simply the continuation of policy with the addition of other means.
-Carl von Clausewitz 2 The history of war is also a history of its justification.Throughout the centuries, military force has been justified and criticized with reference to narratives framed from multiple normative spheres: politics, morality and law. 3 At the heart of this scholarly search for the normative foundations of international order lie the theories of just war (bellum iustum). 4In early modernity, the theory of bellum iustum was contested -in particular, the idea of the just cause (causa iusta) -the normative core of the doctrine of the 'just war' -had lost its plausibility for many lawyers against the background of confessional disputes and the formation of the modern nation-state and its monopoly of power. 5The discourse on justifying war was caught between the political will to power, natural law and secular concepts of legalization. 6ollowing Wilhelm G. Grewe (1911-2000), an overwhelming scholarly majority believes that there has been a turn in legal treatises in the early modern times as part of a historical process of overcoming the moral theological approach of just war (bellum iustum). 7This process, argues Grewe, was finally completed in the 19th century; Grewe and his followers therefore support the theory of so-called liberum ius ad bellum.It suggests that, in the 19th century, European states were no longer bound by the moral criteria of bellum iustum but that they held the sovereign right to go to war.'Whenever the problem of war was seriously discussed from an international law perspective,' writes Grewe, 'the principle of the freedom to wage war … emerged.' 8 1 I. Kant, Project for a Perpetual Peace: A Philosophical Essay (1795, reprinted 1891), at 99.  Consequently, bellum iustum would have lost its relevance as a normative framework during the 19th century.This thesis is widely accepted, 9 whereas some scholars have argued that the justification of war in the 19th century has been an extra-legal phenomenon. 10Only recently, the continuing importance of natural law for the justification of the use of force has been problematized. 11nterestingly enough, the 19th century does not seem to have been of great scientific interest to research concerning the bellum iustum theory and, more generally, the justification of war so far.Questions regarding the 'just war', the resort to war, ius ad bellum and its justification have widely been ignored.This is puzzling.Only since World War I has the just war doctrine gradually been rediscovered, 12 while it seems to have been 'in the shadows', though not fully forgotten, during the 19th century. 13here is some evidence that so far not enough attention has been paid to the doctrine and the legal treatises of the 19th century with respect to the question of a normative judgment on the resort to war.Grewe's argumentation seems to support this impression.As Grewe shows, the terms that describe the emergence of the 'principle of the freedom to wage war' -freies Kriegsführungsrecht, Kriegsfreiheit, liberté à guerre and compétence de guerre -only became customary after 1919. 14As it appears, Stephen C. Neff 's assumption that the 19th century, 'extraordinarily, is the least explored area of the history of international law' is particularly true with respect to the justification of war. 15A differentiated analysis of the normative status of war in international legal discourse is absent not only in classical works like Grewe's Epochs but also in more recent treatises.
Although offering one of the most detailed treatises on the subject in contemporary discourse, Grewe primarily cites contemporary authors and research literature, which 116 EJIL 29 (2018), 113-136   seem to support his thesis of a free right to wage war in the 19th century.Of particular importance in Grewe's presentation of liberum ius ad bellum, which, according to him, was of continental origin, is German lawyer Karl Lueder (1834-1895), who 'rejected the qualification of war as a means of legal appeal'. 16Grewe briefly mentions a second group of authors who understood war as 'a procedure which was provided for and regulated by international law for the enforcement of legally protected claims and interests'.17However, according to Grewe, neither they nor Anglo-American interpretations of bellum iustum theories made a 'substantive difference to the freedom to wage war'. 18 more differentiated view on the 19th-century discussion of war has been offered by Neff.Neff identifies remnants of just war thinking in the ideas of Johann Caspar Bluntschli (1808-1881), H.W. Halleck (1815-1872) and Traver Twiss (1809-1897) but, to Neff, just war principles were 'somewhat disembodied' and replaced by the 'positivist synthesis' of the 'laissez-faire era' in international politics. 19'War was now forthrightly seen as an instrument for the advancement of rival national interests', writes Neff: 'The idea of law governing the resort to war -the ius ad bellum of lawyersshrivelled into virtual nothingness in the face of the positivist challenge.The decision to resort to war … was the prerogative of policy, not of law.' 20 While Grewe and his followers identify dissident voices, they marginalize the discursive importance of bellum iustum and the criticism of war in 19th-century legal discourse.Thus, the acceptance of liberum ius ad bellum takes the place of a deeper analysis of contemporary legal thinking, while dissenting histories are silenced.As becomes obvious, a detailed study of the so-called liberum ius ad bellum and the im portance of bellum iustum in the 19th century is missing, raising the question: how far is this basic assumption of Grewe and his followers true or false?In what follows, Grewe's thesis will be contested by a detailed look at the relevance of bellum iustum and ius ad bellum in 19th-century international legal discourse.Therefore, the continuous connection between moral, political and legal narratives regarding the resort to war in 19th-century international legal doctrine will be thoroughly investigated, and concepts of political legitimations of war, attempts at the legal prevention of war and existing approaches of bellum iustum in the so-called 'positive century' will be confronted. 21o anticipate the findings of my comparative analysis, let me indicate that there are some convincing arguments in favour of Grewe's thesis that liberum ius ad bellum existed.As Grewe suggests, this thesis was widespread in German legal doctrine after the German unification in 1871.It was held by authors who argued in a realist tradition, here described as Clausewitzian.Thus, one focus will be on German legal discourse in the late 19th century.Nevertheless, the seeming confirmation of the thesis of liberum ius ad bellum should not obscure another contemporary legal theory: the legal doctrine of those scholars who were in favour of a legal prohibition of war.Both strands of thought drew from contrary concepts of law (positivistic versus natural law concepts).
Moreover it will be illustrated that the analytical combination of contemporary legal theory and political practice may enrich the debate in the sense of a critical legal history of the politics of justifying war. 22An analysis of the role of law in 19th-century war discourses of state practice is missing so far, but it may be decisive for the theoretical debate between Clausewitzians and Kantians.The fundamental argument of the article, therefore, is that the justification of war in 19th-century legal doctrine and state practice has to be investigated more carefully than before.The present article contributes to this task.It posits that the so-called liberum ius ad bellum constitutes a myth of international legal doctrine.

The Dialectics of a Normative Dichotomy: War and Peace in 19th-Century Legal Discourse
In terms of 'war' and 'peace', the 19th century was a century of great ambivalence, shaped by normative paradoxes.It has been argued that the 19th century was the most peaceful century in modern European history. 23In fact, between 1815 and 1914 only five wars between great powers took place.The Congress of Vienna (1814-1815) sounded the bell for a century of political cooperation via congresses, conferences and multilateral diplomacy. 24The legal institute of 'neutrality' appears to simultaneously support the findings that war had become a political affair beyond general community interests, on the one hand, and the idea of an establishment of international peace through law, on the other. 25However, the 'long peace' between the European great powers in the 19th century 26 was by no means a non-violent order. 27Rather, it was a precarious armistice between the great powers, based on their diplomatic cooperation and military intervention in weaker states as well as expansion and (informal) EJIL 29 (2018), 113-136   imperialism in non-European territories. 28Peace went hand in hand with military force, violent suppression and control. 29he paradoxes and ambivalences of war and peace in 19th-century Europe clearly can be identified in contemporary political practice and legal doctrine.Both were divided between the aims of preventing and, more importantly, humanizing war, on the one hand, and an acceptance of war as a political instrument -an ultima ratio for self-help in the Hobbesian tradition -on the other hand. 30Though mostly ignored in the history of international law, the legitimacy of war became a controversial dispute in contemporary legal discourse.Important intellectual resources for the differing theoretic evaluations were (and are) the philosophers Immanuel Kant (1724-1804), Georg Wilhelm Friedrich Hegel (1770-1831) and a military theorist, Carl von Clausewitz (1780-1831).
Both Kant and Hegel rejected the horrors of war, but they held contrasting views on the value of international law.In his proposal on 'Perpetual Peace', published in the turmoil of the French Revolution (1795), Kant demanded complete legalization and institutionalization of national, international and global human relations via positive law in order to overcome war with an eternal legal peace (ewiger Friede). 31He refused the notion of a right to go to war because of 'the one-sided maxims that operate by means of force'. 32Instead, Kant outlined a legal prohibition of war (ius contra bellum) derived from practical reason. 33nlike Kant, Hegel argued against the binding power of international law.Highlighting the centrality of state sovereignty, Hegel rejected Kant's project for a universal perpetual peace.For Hegel, law required a power to execute it; without an earthly judge -a praetor -over self-sufficient states, war was part of the right beyond the state (das äußere Staatsrecht) and a legitimate mechanism for dispute settlement.The only higher praetor in the Hegelian sense was the world spirit (Weltgeist). 34hile Kant and Hegel were discussing the relationship between war and law, Clausewitz took another route of argumentation.He understood war as a 'clash between major interests that is resolved by bloodshed' and added: '[T]hat is the only way in which it differs from other conflicts.' 35Clausewitz's main argument was the dominance of politics with regard to war.From this perspective, war was not a question of legality or legitimacy but, rather, a political instrument, 'simply the continuation of policy with the admixture of other means'. 36For Clausewitz, war did not take the form of law enforcement in the sense of bellum iustum but, instead, was seen as 'nothing but a duel on a larger scale' -'an act of [physical, HS] force'. 37n 19th-century legal discourse, the impact of these different perspectives on peace and war can be identified clearly.Legal opinions diverged sharply.Russian crown jurist Fedor Fedorovich Martens (1845-1909) aptly described the range of normative judgments in modern war discourses expressed by philosophers (he mentioned Baruch Spinoza, Kant, Joseph de Maistre, John Stuart Mill, Pierre-Joseph Proudhon, Théophile Funck-Brentano, Adolf Lasson), lawyers (Robert Phillimore and himself), military authors (Clausewitz, Wilhelm Rüstow, Gustav Ratzenhofer, Julius von Hartmann), political publicists (Richard Cobden, Heinrich W. Wiskemann, Heinrich Treitschke, Carlo Fiorilli) and a journalist (Émile de Girardin) as follows: 'Everyone knows what war is, but it is clearly not easy to define it scientifically.Former definitions show greatest variations.' 38 In fact, a precise scientific definition was not easily achieved in 19th-century legal theory, even if the current omnipresence of Grewe's thesis of liberum ius ad bellum may let one think differently.What was virtually unambiguous was the definition of the sovereign, 'civilized' (that is, European) state as the primary subject of war, even if some exceptions were considered. 39Nevertheless -and this is a basic argument of the present article -the normative evaluation of war was controversially discussed among legal scholars.Superficially, their opinions can be categorized into two competing viewpoints distinguished by legal and political perspectives: first, 'war' as law enforcement in the broader sense of bellum iustum and, second, 'war' as an armed duel between sovereign states in the sense of liberum ius ad bellum.
Some international lawyers defined 'war' in the style of Clausewitz, as a natural force, which often occurs as a political instrument -Fortsetzung der Politik in anderer Form -as German lawyer Karl Lueder (1834-1895) expressed it. 40For Lueder, war was an empirical fact of physical force. 41He therefore rejected any definition of war as a legal term.This Clausewitzian school of thought among lawyers evolved particularly in Imperial Germany, where some jurists were in close proximity to the military.After German unification in 1870-1871, German lawyers felt the pressure to combine the new geopolitical power of the Kaiserreich under Otto von Bismarck (1815-1898) with international legal obligations.In this context, the idea of the will of the state became an important narrative. 42

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EJIL 29 (2018), 113-136   War was understood as a historical constant, which in spite of its brutality and terror had the meaning of an exponent of progress, a necessary instrument for the further development of civilization -ein wahrer nothwendiger Culturträger. 43War was consequently the normal condition of international relations, which was in harmony with 'divine order' (göttliche Weltordnung).It was not only a law of the world (Weltgesetz) -here one may suspect the impact of Hegel -but also a political instrument to gain national honour, power and the independence of the sovereign state in its own right -here, one can clearly see the impact of Clausewitz. 44owever, these realistic views on the historical dialectics of war and order were by no means simply taken for granted in legal discourse, as Grewe and his followers claim.On the contrary, they were challenged by liberal lawyers, who were in favour of a legal prohibition of war. 45Legal authorities like the famous Swiss lawyer Johann Caspar Bluntschli, a co-founder of the (Nobel Peace Prize winning) Institut de Droit International, as well as Henry Bonfils (1835-1897), a professor in Toulouse who considered war a scandal because of its inhuman brutality.Following Bonfils, war, conducted for whatever reason, was an evil.Even justified wars were therefore morally reprehensible. 46From these moral scruples, Bluntschli, Bonfils and others concluded in normative opposition to Lueder and his colleagues that peace was the normal condition of international relations. 47In times of peace, assumed Bluntschli, law ruled, not force. 48While the Clausewitzians took war for granted, liberal lawyers like Bluntschli believed in the possibility of international peace through law.
Still one can find a curious paradox in Bluntschli's treatise regarding the dialectics of war and order.Citing Friedrich Schiller's (1759-1805) 'Die Weltgeschichte ist das Weltgericht' ('World History Is the World's Tribunal') from the poem 'Resignation' (1786), Bluntschli admitted that under the existing natural conditions and an inexorable desire to overcome outdated law, war could sometimes be seen as an irresistible necessity. 49Being a supporter of Bismarck's unification policy, 50 Bluntschli argued in favour of the 'holy, natural and important right' of a Volk to national unity; even if this 'natural right' required a resort to violence. 51Bluntschli's argument was based on legal, not power-political or military progress; however, some form of a dialectic understanding of the relationship between war and order was present both in Clausewitzian and liberal legal thought.Peace and war were seen as being historically interwoven.
Bluntschli and his followers' scandalization of war was taken up and heavily criticized by some contemporary legal scholars.Many of the lawyers, who criticized Bluntschli, could be labelled as Clausewitzians: 'War is fighting, and there is nothing abnormal about a fighting man, so why should men fighting in a body be abnormal?',wrote American lawyer Roland R[oberts] Foulke from Philadelphia. 52For Clausewitzians, war was a fact, not an object for philosophical reflections.Referring to Kant and liberal lawyers, Karl Lueder argued that the realization of perpetual peace was unthinkable and impossible.For him, it was ein unerreichbares Ideal -and not even the right ideal at all -because war was natural and necessary. 53These were realists' answers to the liberal project of a legal prohibition of war, favouring a turn from the universal vocabulary of justice to the empirical facts of history.
To sum up, within the legal discourse, there were contradicting voices concerning the status of war in history.Some judged it morally evil in the Kantian sense, others legitimated it as the normal -indeed, honourable -procedure of international relations in a Hobbesian or Clausewitzian sense.Consequently, it is possible to identify competing normative arguments derived from political, legal and moral spheres in the treatment of war in 19th-century legal discourse, which make it plausible to use the term of 'multi-normativity' in this topic area. 54Based on these research results, the next section will unveil the impact of these different normative statements on the question of a legitimate or legal use of force in international relations -that is, the dualism of liberum ius ad bellum in the sense of war as a political duel and just war thinking (bellum iustum) in contemporary legal discourse.As will be shown, a passionate dispute arose around the legitimacy of war in 19th-century legal doctrine, especially after 1870, as both legal positivism and natural law thinking were faced with a particularly poorly regulated policy field.Did lawyers claim liberum ius ad bellum within this framework?

Multiple Justifications of War: Bellum iustum, ius ad bellum and ius contra bellum in 19th-Century Legal Discourse
Whereas war had been a central topic in every treatise of international law, there were hardly any comprehensive or concluding investigations of the legitimacy of resort to war in 19th-century legal doctrine.This is an observation I share with German lawyer Heinrich Rettich.In 1888, Rettich criticized contemporary international lawyers for not having come up with a widely shared positivist understanding of war and its functions in history.As the former chapter has revealed, Rettich's argument had some plausibility.However, even more unsatisfying -bei manchen höchst unklar und unlogisch, 52 Foulke, supra note 40. 53Lueder, supra note 40, at 196-199, 203. 54 as Rettich wrote polemically -was the scientific treatment of the justifying causes of war -die Lehre von den rechtfertigenden Kriegsursachen. 55From his overview of 19thcentury international legal discourse, Rettich argued, in accordance with Grewe's thesis of liberum ius ad bellum, that there was a positive right to wage war -ein Recht zum Kriege -based on a state's interests and necessities. 56However, at this point, my agreement with Rettich ends.In fact, there was a respectable group of lawyers in the 19th century who understood war as a legally irrelevant, but valid, political instrument.They thereby supported the idea of the free right of the state to go to war as the acme of state sovereignty. 57For instance, Emanuel Ullmann (1841-1913), former professor of public and criminal law in Vienna and successor of Franz von Holtzendorff (1829-1889) in Munich from 1889, argued that every war was legal because a sovereign state accepted only its own politics as legally significant. 58Not surprisingly, many of these advocates of a realist view on international war were the same authors who had already argued in favour of the civilizing and regulative value of war in history.German lawyer Paul Heilborn (1861-1932) agreed with Ullmann by characterizing war as 'absolutely permitted in inter-State relations'. 59In treatises of jurists such as Heilborn and Ullmann, therefore, one can identify contemporary sources for Grewe's thesis of a free right to wage war.How was this liberum ius ad bellum reasoned in Clausewitzian international legal theory?One of the most precise descriptions of war in the sense of the Clausewitzian state duel was given by John Westlake (1828-1913), then professor for international law at Cambridge University in England. 60Westlake argued that a war between 'civilized states' was begun because of some demand or some complaint of one state against another.Still, for Westlake, when it came to the legitimacy of war, international law 'says its last word on that point when it pronounces the demand or the complaint to be legitimate or illegitimate, and if possible, offers arbitration'. 61However, on a second level, he argued that the question of the legitimacy of war could be put aside if states were not content with peaceful conflict offered by international law: '[T]he want of organisation in the world of states compels the law which was concerned with their dispute to stand aside while they fight the quarrel out, in obedience not to the natural law of philosophers, which is a rule prescribing conduct, but to that of the natural historian, which is a record of the habits of the species, good or bad.' 62 Three aspects of Westlake's definition of war between states make it a particularly interesting summary of the Clausewitzian approach.First, there is the assumption that two states could jointly decide to ignore questions of the legitimacy of war in order to solve their 'quarrel' by resorting to armed force instead.For Clausewitzians, war became a duel between two states over opposing political interests.Like Clausewitz, Lueder and Alphonse Rivier (1835-1898) argued that the definition of 'war' presupposed violent acts on both sides. 63Here, one may remember Clausewitz's famous definition of the beginning of a state duel: 'War begins only with defence' ('Der Krieg beginnt mit der Verteidigung'). 64econd, there was the claim that international law was to 'stand aside' during a duel, as argued by Westlake.The normative power of right was to be subordinated to factual might.The legitimacy of war was to be ignored since, for Clausewitzians, war was not law enforcement but, instead, each belligerent simply strove 'to break down the resistance of the other to the terms which he requires for peace'. 65This definition clearly goes beyond the concept of war that is limited to sanctions in the sense of bellum iustum.Wars were not necessarily limited 'to the concession of the demand or the satisfaction of the complaint out of which the war arose' but, rather, could include cession of territory or even the extinction of the weaker state by conquest. 66or Clausewitzians, normative limitations in the sense of just war theory and, with it, the very idea of justice with respect to war were parts of the past and belonged to the medieval bellum iustum theory.According to them, states had never differentiated between just and unjust war in the legal sense; the distinction thus had no effect on the fact of war. 67Where sovereign states decided to fight a duel, law could not prevent them from seeing war as a necessity.Thus, the concept of 'military necessity' took the discursive place of morality and law.As we can clearly reconstruct, Clausewitzians declined the just war doctrine as being incompatible with a political, demoralized 'right of the stronger'.In order to avoid a regulation of the 'necessity of war', these lawyers denied the theory of bellum iustum as well as the positivistic legalization of war (ius contra bellum).For them, the ius ad bellum was, exactly as Kant had criticized it in 1795, a prerogative of sovereignty. 68Law was seen as providing mitigating rules; thus, only the ius in bello was accepted as legally binding by Clausewitzians. 69However, in the German Kaiserreich, lawyers like pro-military Lueder and Ullmann were particularly taken with the idea of a selective use of the normative force of ius in bello in light of military needs 70 -Kriegsräson geht vor Kriegsrecht (the raison of war overrides the laws of war). 7124 EJIL 29 (2018), 113-136   Third, the Clausewitzians' neglect of the legitimacy of war as well as their denial of bellum iustum was clearly based on a purely positivist-empirical concept of law.It fell on fertile ground in the German context after 1870-1871, when international lawyers forged ahead with the transformation of their science into positivism.Here, the claim for liberum ius ad bellum was particularly strong.Some parts of German legal doctrine were shaped by a turn to a sociological language, which can be identified in Ullmann's Völkerrecht. 72Clausewitzian lawyers argued in favour of war as a physical fact -a lex lata naturae -which was not to be judged normatively. 73The just war doctrine was to be overcome.In Clausewitzian positivism, bellum iustum was an outdated natural law conception.In contrast to the 'natural law of philosophers', Clausewitzians only accepted empirically demonstrable, as well as enforceable, law as 'true law': '[T]hat of the natural historian, which is a record of the habits of the species, good or bad.' 74 For them, natural law was inappropriate as a source of law.
Given the fact that there was no prohibition of war and 'no rule concerning when war may be waged' by the second half of the century, it appeared to Clausewitzians that international law could only be enforced to a small extent. 75From their strictly factual-positivist standpoint, the legitimacy of war was not a relevant question of international law but, if at all, one of international morality. 76'But modern International Law knows nothing of these moral questions', argued British lawyer Thomas Joseph Lawrence (1849-1920), lecturer at Cambridge University in England and in Chicago in the USA, in his perfect summary of this perspective on war and law: 'It does not pronounce upon them: it simply ignores them.To it war, whether just or unjust, right or wrong, is a fact which alters in a great variety of ways the relations of the parties concerned.' 77To some extent, it was a capitulation before the 'reality' of war.
Does this mean that bellum iustum had been forgotten in the 19th century?Not at all! Whereas the discrimination between just and unjust wars was central to moral theological and legal writings in pre-modern Europe, the terms 'just war', gerechter Krieg and guerre juste can, interestingly enough, still be found in legal writings of the 19th century.The first piece of evidence is that Clausewitzian writers felt the need to distance themselves from bellum iustum arguments. 78Thus, it still had a discursive meaning in 19th-century legal doctrine, even for Clausewitzians.In 1888, Rettich assumed that he was writing against a mainstream legal discourse dominated by bellum iustum; 79 from a genealogical perspective, Rettich's assumption is particularly interesting as it strongly supports the thesis that liberum ius ad bellum was fully developed only in the last third of the 19th century by Clausewitzians.For these lawyers, bellum iustum was -or, at least, should have been -replaced by liberum ius ad bellum.Furthermore, in their positivist outlook, bellum iustum and liberum ius ad bellum could not coexist as separate legal theories (that is, in the sense of a distinction as the first belonging to natural law, the second to positive law).For them, a moral perspective on war was fully inappropriate for international law.Most importantly, as they constantly cited the just war tradition, it now becomes obvious that their idea of liberum ius ad bellum was actually a historical modification of the bellum iustum tradition, overcoming right intention and just cause but focusing on the right authority -that is, the sovereign state. 80For Clausewitzian lawyers, not only was war to be freed from bellum iustum limitations but also, even more, liberum ius ad bellum had emerged from the bellum iustum theory during the early modern times. 81According to them, the pursued transformation from bellum iustum to liberum ius ad bellum was also a shift from natural law to a sociological positivism of military necessity, which was finally completed in the last third of the 19th century.
However, there is a second, even more striking piece of evidence that supports the thesis that the just war tradition, albeit in a broader sense, still had an important impact on international legal theory -namely, the Clausewitzian perspective on the free resort to war by states was contested through moral and legal arguments derived from the just war theory.Before the dispute between the Clausewitzians and liberals reached its climax in the second half of the century, a well-known 19th-century lawyer, the German August Wilhelm Heffter (1796-1880), professor of law in Berlin, had already referred to a just war -gerechter Krieg -from a positivistic perspective.His Das Europäische Völkerrecht der Gegenwart was praised by European lawyers as one of the best legal treatises on positive international law. 82Heffter defined 'war' solely as the use of utmost, even destructive, force in favour of the realization of legal purposes: 'Ein Rechtsbegriff wird der Krieg erst, wenn man sich ihn als Anwendung des äußersten selbst vernichtenden Zwanges wider einen Andern denkt, zur Realisirung rechtlicher Zwecke bis zur Erreichung derselben.' 83For Heffter, who shared some similarities with Hegel, war was, 'with other words', the ultimate self-help. 84owever, in accordance with many scholars with a legal background -and in total contrast to the definition of war as a pure fact used by German lawyers later in the century, whom I call Clausewitzians -Heffter distinguished between defensive wars to ward off an unjust attack and offensive wars, which were waged for the purpose of satisfaction. 85Here, Heffter identified the boundary line between war and justice -a war was only just to the extent that self-help was allowed. 86For Heffter, an unjust war -der ungerechte Krieg -was actually equal in its effects to a just war; da er, argued Heffter, 126 EJIL 29 (2018), 113-136   dem gerechten thatsächlich gleichsteht. 87In an analogy to Hegel (and Alberico Gentili), Heffter explained this factual non-difference between just and unjust wars with the lack of an earthly judge, by whom justice or injustice of a war could be sentenced.
This contradiction between the factuality of war and a pursued positivist international legal order reflects the liberal challenge to integrate bellum iustum as a moral theory into 19th-century legal discourse; political scientist Robert von Mohl (1799-1875), professor in Tübingen, agreed with Heffter.For him, war was ultima ratio regum in order to defend the law and save the international legal order from violent anarchy.For Mohl, the ultimate reason for war was the restoration of law and peace. 88This was a definition of war as legal enforcement, which can also be found, with even stronger reference to classical, moral theological concepts of bellum iustum, in contemporary legal discourse on 'measures short on war' like 'reprisals' 89 and '(humanitarian) intervention'. 90For Martens, an intervention could be justified in the name of 'international community', with recourse to the 'commonality of religious interests and the commandments of humanity, that is the principles of natural law [sic!]'. 91Thus, natural law was still alive at the end of the 19th century.However, for liberal lawyers, the binding power of law was not just limited to 'measures short of war' but was also applied to the legal justification of war.
Robert Phillimore (1810-1885) called war a 'terrible litigation' between states, and Martens rightly acknowledged Phillimore's legal position to be in total contradiction to Clausewitz's concept of war as a state duel. 92Other lawyers also argued likewise, with recourse to bellum iustum, by the second half of the century, when the Clausewitzian legal doctrine was in full bloom.Like Heffter, Bluntschli identified a war to be just (gerecht) if armed self-help could be justified by international law and unjust (ungerecht) if it was in contradiction with the rules of international law: 'Der Krieg ist gerecht, wenn und soweit die bewaffnete Rechtshülfe durch das Völkerrecht begründet ist, ungerecht, wenn dieselbe im Widerspruch mit den Vorschriften des Völkerrechts ist.' 93 Argentinian lawyer Carlo ('Charles') Calvo (1824-1906), another co-founder of the Institut de Droit International, agreed in 1885 that war could be considered just if international law authorized the recourse to arms, and, therefore, it could be considered unjust if it was against the principles of law: 'Légitimation de la guerre: … En résumé, une guerre peut être considérée comme juste, lorsque le droit international autorise le recours aux armes; comme injuste lorsqu'elle est contraire aux principes de ce droit.' 94 And August von Bulmerincq (1822-1890) argued that a state that was harmed in its 87 Heffter, supra note 83, at 195. 88 R. von Mohl, Encyklopädie der Staatswissenschaften (1859), at 453ff. 89Neff, supra note 3, at 225-227. 90For 19th-century international political theory, see Jahn, 'Humanitarian Intervention: What's in a Name?', 49 International Politics (2012) 36. 91F. von Martens, Völkerrecht: Das internationale Recht der civilisirten Nationen (2nd edn, 1883), vol. 1, at 302. 92 Martens, supra note 38, at 476. 93 Bluntschli, supra note 39, at 290. 94 Calvo, supra note 85, at 366ff.fundamental rights by another state was justified to use war as a Rechtsmittel.To him, only a war waged in order to defend its right was justified: 'Nur der Vertheidigungskrieg ist völkerrechtlich gerechtfertigt.'95Moreover, in the tradition of bellum iustum, a war was only legitimate for the purposes of restoring violated rights and achieving compensation; war was not a political instrument but, rather, one of law.Therefore, recourse to the coercive violence of war is not justified by the Clausewitzian necessity of war but only by the necessity of law (Rechtsnothwendigkeit; 96 Rechtsgründe 97 ).
For Bluntschli, it was not only a question of morality but also an imperative of lawnicht bloß ein moralischer, sondern ein wirklicher Rechtssatz. 98Legal reasons for a war, he argued, were (a serious threat of) infringements of rights, trespasses against a state or a grave breach against the world order.Similar to early modern just war theory, a violation of rights was the central criterion to Bluntschli's legal conception of war, but, in contrast to it, the causa iusta was to be legalized -in other words, to be transformed into positive law.In the legal writings of the 19th century, if the legitimization of war had been described in terms of just and unjust, then 'just' or 'unjust' meant generally the same thing as 'legal' or 'illegal'. 99Thus, it appears that the conception of war found in Bluntschli's treatise can be understood as an early attempt at a modern ius contra bellum, based on the idea of peace through law. 100 Here, one can see the influence of Kant's legal philosophy and his concepts of international and global legal society (Völkerrecht/Weltbürgerrecht). 101evertheless, as Bluntschli admitted, a legal limitation of the resort to war was, for the time being, of little practical importance because there was no impartial judge to differ between just/legal and unjust/illegal wars. 102Since no treaty generally prohibited war, Bluntschli understood that there was a long way to go for international law to transform violent international conflicts (violentia) into truly legal conflicts (potestas).The early modern question 'quis iudicabit?' was still lacking an answer in positivistic terms, and, along with it, the theoretical and methodical problems of the concept and sources of international law had arisen.In contrast to the Clausewitzians, who turned (and surrendered) to the sociological-empirical 'factuality' of war, liberal lawyers did not take the lack of a positivist legalization as immutable.Bluntschli and his followers therefore combined two normative spheres in their criticism of war as a political instrument: law and morality.Bluntschli argued that it was in the interest of humanity (großes humanes Interesse) to outlaw the 'barbaric view' of war (barbarischen Standpunkt) as violent self-help in the sense of the medieval feud. 103For Bluntschli, a 128 EJIL 29 (2018), 113-136   prohibition of war was a legal and moral imperative for the civilizing progress of the international normative order.The combination of moral and legal arguments on which these early concepts of modern ius contra bellum were founded resulted in a debate about legal methodology.German lawyer Carl Gareis (1844-1923), a lecturer in Königsberg and Munich, wrote in 1888 that Bluntschli had spoken de lege ferenda -about the law to be -not de lege lata -about the current law. 104This was a critique similar to the more general one of English legal theorist John Austin (1790-1859), for whom law was the sovereign's command backed by a sanction.Since international law lacked a reliable enforcement system, for Austin, it was not law but, rather, 'positive morality'. 105These considerations were widespread in Clausewitzian theory.Similar to Gareis, Rettich in 1888 criticized Heffter, Bluntschli and Bulmerincq for their views on war as law enforcement; to Rettich, Blumerincq's argument, drawing from the bellum iustum tradition, was 'pure philosophy' based on natural law thinking and, therefore, technically inappropriate in a legal sense. 106n the contrary, lawyers like Bluntschli and Bulmerincq were influenced by the historical school of law of Friedrich Carl von Savigny (1779-1861).Admiring Savigny's 'supra-national historicism', 107 international law for liberals was a narrative of human progress and of 'moral and civilizing forces'. 108In contrast to Austin's command theory, liberals founded their concept of law not on enforceability but, rather, on 'historical jurisprudence, linked with liberal-humanitarian ideals and theories of natural evolution of European societies'. 109It was not primarily to be derived from contracts but, instead, from the 'legal conscience of the civilized world'. 110Consequently, Bluntschli referred to the concepts of 'law to come' (werdendes Recht) and 'living law' (lebendiges Recht). 111hile the Clausewitzians' positivism referred to absolute sociological-empirical 'facticity' and was thus in strong contrast to natural law, for liberal idealists like Bluntschli and other members of the Institut de Droit International (the 'men of 1873'), positive law was part of law as a 'living institution', 112 an 'empirical underpinning' that had to be developed from the 'overall world view' of natural law. 113Since there was not (yet) a legal sanction for unjustified wars in positivistic terms, the Clausewitzian theory of 'law' that was derived from absolute sovereignty led to liberum ius ad bellum.In contrast, liberal legal doctrine based on the concept of an international community -that 130 EJIL 29 (2018), 113-136   and, even less, the 'real' motives of the war parties.This problem is reinforced by the fact that the empirical material -that is, the number of wars in the (European) 19th century -is limited.'History', as Neff has put it correctly, 'is no subject for purists'. 121 war that most likely would feature as a duel may be the Austro-Prussian War (1866).It was waged with a precise political goal (a decision on the process of German unification); furthermore, the war's outcome resulted largely from a decisive battle near Königgrätz on 3 July 1866.122 Helmuth Graf von Moltke (1800-1891), Prussian chief of the general staff and a disciple of Clausewitz, thus saw in it the ideal of a cabinet war, defined by limited, short and decisive fighting as well as by the absence of ideological public debates.123 However, even if one accepts the 1866 war as a Clausewitzian state duel, it appears to be an exception to the rule -both with regard to 19th-century warfare as well as to war discourse (there were no official declarations of war in 1866).
However, it is highly problematic to apply the duel concept to the next war -the Franco-Prussian War (1870-1871).The Franco-Prussian War can be understood as a hybrid war between the 18th-century 'cabinet wars' and the 20th-century 'total wars'.Analogously to the 1866 war, this war began with a limited goal (preventing or fulfilling German unification), but after the French defeat at Sedan, it was transformed into an industrialized 'people's war', shaped by public nationalism, violence against civilians and partisan attacks against the Prussian invaders performed by Francs-tireurs. 124Moltke, in turn, denied the Francs-tireurs the status of combatants and ordered summary executions. 125In fact, the Franco-Prussian War pointed to the end of the duel war in the Clausewitzian sense as well as to the rise of total war.'The age of cabinet's war is behind us, -now we have only people's war', Moltke would express in his last speech in the Reichstag on 14 May 1890. 126urthermore, and clearly against the thesis of liberum ius ad bellum, the Franco-Prussian War was accompanied by discourses on its legitimacy both in domestic and foreign arenas.Public opinion had quite literally urged the French government to declare war against Prussia in 1870 after Bismarck had intentionally provoked it by shortening the Emser Depesche (making the French believe that King Wilhelm I had harshly rejected the demand for a further renunciation of a Hohenzollern candidate for the Spanish throne). 127The war was not only an instrument of sovereign policy but also depended on public legitimacy.Napoleon III was correct to note in his speech of 21 July 1870 that it was 'the whole nation which has, by its irresistible impulse, dictated our decisions [to go to war]'. 128rance considered it necessary to stress that it was not waging a war out of political ambitions but, rather, that it was 'a war of equilibrium' -a 'defence of the weak against the strong, the reparation of great iniquities, the chastisement of unjustifiable acts'. 129Thus, Napoleon III (1808-1873) literally emphasized the 'just cause' of his 'defence' against 'Prussian egotism', upon which Europe should pronounce -a prime example of the justifications for 19th-century bellum iustum doctrine! 130Even though Clausewitzian lawyers claimed an unlimited sovereign right to go to war, justifications in state practice spoke a different language, pointing at international peace, stability and the preservation of national rights.Echoing these sentiments, the French official account of the origin of the war held 'that the rights of each nation, like the rights of each individual, are limited by the rights of others, and it is not permissible [sic] that one nation, under the pretext of exercising its own sovereignty, should menace the existence or the security of a neighbouring nation'. 131Military necessity was denied status as a just cause of war.Here, one can find a clear rejection of any notion of liberum ius ad bellum.
Discursive legitimacy was also important for Bismarck, who had waited for the French declaration of war (19 July 1870) in order to make France appear to be the aggressor: 'The whole civilised world will acknowledge that the grounds for war assigned by France do not exist, and are nothing but pretence and invention.'Bismarck wrote this the very same day, and he added that both the North German Confederation and the allied governments of the South German states would defend the 'unprovoked attack' (nicht provocierten Ueberfall) with all the means that '[p]rovidence has placed at their disposal'. 132Bismarck had successfully generated national and international sympathy for Prussia and its war aims.However, this changed immediately when Prussia decided to annex parts of Alsace and Lorraine after its decisive victory at Sedan (1 September 1870). 133As can be seen, in 19th-century war discourse, not only was publicity of the utmost importance, but an unlimited freedom to conquer another state's territory was also seen as illegitimate, although it was permitted in Clausewitzian legal scholarship.
EJIL 29 (2018), 113-136 more than propaganda -that is, political rhetoric without any normative meaning. 135owever, by examining the discursive practices more precisely (little research has been conducted in this field so far), 136 Grewe's thesis is scarcely tenable.The Concert of Europe developed a regulative order of peace constituted by power and norms; although this precarious order of peace was based on (military) coercion, the Concert established some form of a diplomatic 'culture of peace' (Friedenskultur) between the great powers. 137It was built on international moderation, multipartite diplomacy and behavioural norms derived from the former. 138As mentioned above, the Concert of Europe did not legally prohibit war.There was no 'undeviating rule applicable to all … cases', as Lord Russell had put it in 1841. 139However, 'the preservation of the peace of Europe' became a desired norm between right and might, which was applied in practice.A state's resort to war was judged by the Concert (just as Napoleon III had asked for in the context of the Franco-Prussian War) and could, if it was not seen as legitimate, result in moderate measures like the withdrawal of the Concert's diplomatic support, as was the case when Austria ignored Russian and British attempts of mediation in 1859 and instead declared war on Piedmont-Sardinia. 140However, it could also result in the authorization of armed measures such as military intervention to maintain or restore international peace and security.Thus, Matthias Schulz's suggestion that the Concert of Europe was a '19th century Security Council' is not im plausible. 141or instance, in the Crimean War (1853-1856), an alliance of the Ottoman Empire, England, France and Piedmont-Sardinia took action against Russia, in a form, which could be labelled an intervention authorized by the Concert of Europe against a Russian 'crusade'. 142The Treaty of Paris (1856) created an international sub-system in Europe by denying Russian responsibility for the protection of Christian citizens in the Ottoman Empire under threat of armed sanction (Articles 7 and 9). 143Still, in 1877, Russian foreign minister Alexander Gorchakov (1798-1883) stated that the independence of Turkey 'must be subordinated to the guarantees demanded by humanity, the sentiments of Christian Europe, and the general peace in Europe'. 144He thus combined arguments from the discourses on 'humanitarian intervention' and the restoration of the European peace -Russia (successfully) broke the treaty of 1856 by referring to natural law!
The politics of justifying war in 19th-century state practice lay exactly between the precarious normative peace architecture of the Concert of Europe and unilateral 135 Grewe, supra note 7, at 531. 136 Cf.Tischer, supra note 6, at 15. 137 Schulz, supra note 23, at 4. 138 Ibid., at 615; Vec, supra note 27, at 658. 139 Schulz, supra note 23, at 617. 140 Ibid., at 481, 617. 141 interests of sovereign states.Not surprisingly, the discourses were shaped by diverse narratives ranging from common European values and norms, positive law, unilateral rights and interests, Christian faith and natural law and national honour to international peace and security.Here, one can rediscover the 19th-century 'multi-normativity' that has been identified in contemporary legal discourse. 145There was no clear positive law ordering ius ad bellum, though, at the end of the century, in the face of rising nationalism, some cautious approaches towards further legalization like the 1907 Drago-Porter Convention were implemented. 146aking these discourses of justification more seriously with respect to the history of war may therefore help to correct the wrong perception of the Clausewitzian notions on Realpolitik and military necessity, and it may help to deconstruct liberum ius ad bellum as an academic myth.Since what can be asserted in analysing the 19th-century politics of justifying war is that states refrained from claiming liberum ius ad bellum.This was even the case when international relations became more contentious after 1870 and when the dispute between Clausewitzians and liberals was fully developed.The fact that Bismarck praised himself in his memoirs for bypassing the Concert of Europe in his unification policy underlines his awareness of the Concert's normative coercion.However, after Bismarck's retirement in 1890, this awareness of the European normative order seems to have been lost within the Kaiserreich's political discourse.The political context favoured arguments offered by the Clausewitzian school of legal thinking.Isabel Hull recently has emphasized the grave German violations of international law in the Great War: 'It is as if Imperial Germany could not speak the same legal language as the rest of Europe.' 147 After two World Wars, the idea of war as a political instrument in the Clausewitzian sense was finally replaced by an international rule of law in the Kantian tradition, which was present in parts of the 19thcentury legal discourse, as illustrated above.

Deconstructing a Myth: The Justification of War as a Forgotten Dispute about Law, Morality and Politics
The 19th century saw the emergence of complex political and legal discourses on the legitimacy of war.Contrary to what Wilhelm Grewe and his followers have claimed, the justification of war and military force in international legal discourse was highly controversial.There was no single, consistent approach or theory in legal thinking about war and its legitimacy; instead, war became a contested area in international legal doctrine, caught between the theories of bellum iustum, liberum ius ad bellum and ius contra bellum.The passionate dispute about justifying war was characterized by arguments originating from different spheres of justice (politics, morality, law).Legal 145  discourse and state practice were therefore shaped by 'multi-normativity', despite positivism. 148wo schools of thinking emerged in 19th-century legal doctrine, differentiated by political and legal mentalities.One school argued against a normative term of war and in favour of war as a political instrument, a duel between states.Lawyers with a political outlook legitimated war as the normal, de facto progressive and honourable status of international relations, not to be condemned as morally reprehensible in the Kantian sense.For them, war was not a term of law or justice but, rather, ein nothwendiger Culturträger, as expressed by Lueder.Clausewitzian lawyers therefore argued in favour of the unlimited right of the sovereign state to go to war, liberum ius ad bellum, and against the need for a legal justification of war.For these lawyers, bellum iustum no longer played a role for waging war.It was replaced by the concept of 'military necessity'.This denial of bellum iustum and natural law was based on a purely positivist-empirical concept of law, shaped by a sociological language.Here we can find contemporary advocates for Grewe's thesis.
However, what often has been ignored in the history of international law is the fact that there was another bloc of lawyers for whom war was morally and legally forbidden -an evil to be overcome through legalization.For them, war was a legal dispute (ein Rechtsstreit) over public international law; thus, war needed a legal justification. 149Bellum iustum still played an important role in this perspective, as war had to be justified in terms of 'just war', even if 'just' more or less meant the same as 'legal'.However, these lawyers referred both to morality and natural law, as positivism alone seemed yet unable to adequately order the justification of war.
With regard to Grewe's thesis, one has to emphasize the intensive disputes between different normative and scientific views on war; the thesis of liberum ius ad bellum was by no means taken for granted in the entire 19th-century legal discourse.While there were voices in favour of war as a political instrument (liberum ius ad bellum), others wanted to prohibit war with recourse to moral and legal arguments (ius contra bellum).The two schools of legal thinking did not simply coexist; lawyers with political and legal perspectives competed with one another over authority in international legal discourse.In fact, even contemporary proponents of the unlimited sovereign right to war grappled with opposite opinions and their multi-normative foundations.
Consequently, one has to ask why the history of international law has focused on a realist perspective on war and law in the 19th century to this point.One possible answer has been given in this article -namely, the historical context of the violent German unification in 1870-1871 was a turning point for dealing with the question of the legitimacy of war.This is not to say that the idea of liberum ius ad bellum was only common in German legal discourse; authors from other countries shared the idea of war as an extra-legal phenomenon, and many prominent critics of liberum ius ad bellum were Germans.Still, a case can be made for the argument that liberum ius ad bellum and 'military necessity' were particularly significant in the legal discourse of the German Kaiserreich.The Clausewitzian tradition in legal thinking prevailed even after World War I, with Carl Schmitt (1888-1985) being its main exponent.In Schmitt's conception of state sovereignty as a precondition of (international) law (ein Rechtsvoraussetzungsbegriff), 150 the sovereign was authorized to use military force; for Schmitt, he therefore had a 'free right to go to war'. 151ut also in this context, the thesis of liberum ius ad bellum in the 19th century had been contested by scholars like Arthur Nussbaum (1877-1964) and Hans Kelsen  (1881-1973).For Kelsen, war was a coercive sanction of the universal legal order. 152emarkably, Nussbaum criticized that Lueder's refutation of a just war, and the thesis of liberum ius ad bellum suffered from 'the infusion of arguments which smack of enthusiasm for war'. 153However, this realist tradition in German legal doctrine has been revitalized by a 20th-century German lawyer, who was deeply influenced by Carl Schmitt and would become the author of a standard book on the history of international law.This author was Wilhelm G. Grewe, whose Epochs of International Law is a history of international law as a history of political fights for hegemony and supremacy. 154Therefore, it is not surprising to find the thesis of liberum ius ad bellum in Grewe's treatise.To some extent, the German, Clausewitzian tradition thereby continued in the history of international law.
Since there were two competing viewpoints in 19th-century international doctrine, a closer look at political practice seems to be appropriate. 155In contemporary state practice, liberum ius ad bellum was not claimed.Justifications of war were caught between unilateral aims and the normative framework of the Concert of Europe.Thus, what seems to be central in writing histories of the politics of international law is the plurality of normative rules and a critical understanding of their (mis-)use in political practice.This plurality calls for interdisciplinary research; norms are disputed in discourses, their authority increases and vanishes throughout history.A 'deconstructionist', 156 critical 'history of normativity' 157 has to dissect the formation and enforcement of normative orders understood as contested systems of knowledge. 158 quasi-genealogical access to the relationship between political practice and legal 136 EJIL 29 (2018), 113-136   theory may help to deconstruct one-sided narratives as academic myths, presenting only a suitable section of the more complex historical truth.An example of such a genealogical approach has been presented in this article.The proposition of so-called liberum ius ad bellum leans on a one-sided, realist tradition in the history of international law, which has been revitalized by Wilhelm G. Grewe.Faced with the highly controversial legal disputes in the 19th century, and with the complex justification discourses in state practice, it seems to be justified to formulate the thesis that liberum ius ad bellum constitutes a myth in the history of international law.
Vec, supra note 54.146Hague Convention 2 on the Limitations of the Employment of the Use of Force for the Recovery of Contract Debts 1907, 36 Stat.2241; cf.Vec, supra note 27, at 660. 147 Hull, supra note 71, at 331.