See also the article "Arbiters and Arbitration in Europe since the Beginning of Modern Times" in the EHNE.

Introduction

At the opening of his incisive 1920 critique of the Paris Peace Conference in the aftermath of the First World War, John Maynard Keynes (1883–1946)[] remarked that "Europe is solid with herself. France, Germany, Italy, Austria and Holland, Russia and Roumania and Poland, throb together, and their structure and civilization are essentially one". The European states may flourish or may fall together,¹ this lay at the bottom of Keynes' view. Were the victors in the "European Civil War" to abuse their position by destroying the vanquished – particularly Germany and the former Austria-Hungary – then ultimately the shockwaves would rebound on them. Implicit in Keynes's analysis was the friction between national interest and the different possible levels and types of international interaction and cooperation, a tension which had a long history in Europe and which was of course particularly intense as Keynes committed his thoughts to paper.

By 1920, Europe had a long history of forging international agreements that aimed to limit the possibilities of a renewed general war, of accommodating the emergence of new states, of attempting to contain revolution and social upheaval and of forging and regulating international markets. In doing all these things, European states frequently came to international agreements that involved putting aside, or at least containing, their latent rivalries, yet at the same time these processes of cooperation did not prevent the periodic eruption of international conflict – not least because treaties and alliances were of course used to press forward the interests of the individual European states, rather than those of the wider European order itself. The extent to which Europeans were concerned about this friction depended upon the nature of the international order that they inhabited.

The background: types of international order

Political scientists have identified at least three different types of international order: the "anarchic", the "hegemonic" and the "constitutional" – terms which are here used in a strictly neutral sense. None of these systems have ever existed in a pure form; rather, the distribution and exercise of power among European states has combined features of each of them, with preponderance from one or another in any given point in time.² An "anarchic" or "self-help" order³ is closely associated with the idea of the "balance of power", which is a highly nebulous concept open to a range of definitions.⁴ Here it is taken as the theory that, in being free to pursue their own separate interests, states reach a point of equilibrium, a distribution of power among them in which no single state, or group of states, is able to dominate the others. The "hegemonic" system is ordered around an international hierarchy, in which a predominant state protects and to varying degrees dominates other states. In some international orders, such "secondary" states may still enjoy their own sovereignty, but the most extreme form of "hegemonic" system is empire, in which the leading state subjugates and coerces the other polities to the point that they are not sovereign.⁵ A "constitutional" order seeks to generate legal norms, to institutionalise them and to make them binding on all parties, as a means of creating a stable international system that minimises violence or eliminates it altogether. A "constitutional" order thus places institutional and legal constraints on the freedom to act of the states subscribing to it.⁶

The contours of each of these models are all discernible in the workings of international relations in Europe between 1450 and 1950, but never in their entirety. The expressed purposes and the unspoken intentions behind the conduct of diplomacy, including alliances and treaties, are shaped by the prevailing type or rules of the system but such attitudes might in turn also determine whether such international agreements operate within the system, or try to change it. In modern Europe, the essential challenge for politicians and scholars addressing international relations has of course been the search for lasting peace and security, a search that – under the impact of evolving circumstances over four centuries – has changed the role and purpose of alliances and treaties. Fundamental to this pursuit has been the problem of international law and the extent to which international agreements were both subject to such law and how far treaties could be used to codify it and institutionalise it. In other words, the history of alliances and treaties between 1450 and 1950 has represented a painful but fitful move away from an "anarchic" towards a more "constitutional" international order, with the occasional injection of not a little dose of hegemony. The fundamental building-blocks of the European order remained the same – the sovereign state – but wider social and political developments over the course of these four centuries have helped alter attitudes about the ways in which such states ought to operate within the international system.

Casting back to the mid-15th century, one of the pivotal developments that underlay international relations in Europe was the gradual emergence of centralising, dynastic states, aimed at increasing the control princes had over their peoples and their resources. At the same time, this increased the costs of conflict and intensified international rivalries. Over the next three hundred years, moreover, this political development was accompanied by a cultural change. Notions of personal honour and chivalry amongst the elites were undercut and replaced by strengthening national identities, notions of patriotism and the "nationalisation of honour", an evolution that shifted theories about what was acceptable behaviour in international relations and particularly in wartime. Chivalry, as a code of individual conduct, could never be the same as more modern concepts of international law that were meant to shape relations between states. In any case, the treatment of the vanquished and of non-combatants was not determined by any overarching notion of international law, but rather by customs and assumptions about what was legitimate behaviour in wartime.⁷ The ideology of the Crusades, moreover, implied that whole peoples might be outside the proper community and so be unprotected by the chivalric notions of the law of arms.⁸

Within Christian Europe, these processes were given momentum by the 16th-century confessional division within Europe between Catholic and Protestant, which were thought to have corroded some of the restraints on the ways in which warfare was conducted. Such sectarianism was not a new experience for Europeans, since they already contended with the long-standing divisions both within Christendom, between Roman and Orthodox and without, between Christendom and Islam. Even so, the rupture of the single Roman Church, and ultimately the assertion of the supremacy of the secular state over the churches accelerated a process whereby Europe was re-conceptualised less as Christendom and more as an international system with multiple, competing parts.⁹ The Treaties of Utrecht in 1713 were the last to speak of the European states collectively as the Res publica Christiana,¹⁰ although the Treaty of Aix-la-Chapelle (Aachen) in 1748 still spoke of a "Treaty of Christian, Universal, and Perpetual Peace and Union".¹¹ The system of competing sovereign states that appeared to be emerging looked all the more brutal because its rivalries were overlaid by ideological differences, religious then national. Developments in the 18th and 19th centuries – the assault on privilege, the expansion of the state, the emergence of civil societies, the emancipation of the peasantry and the advancement of concepts of citizenship, Europe's continued expansion overseas and the evolution of nationalist ideologies – all undertaken and harnessed by liberal and authoritarian regimes alike – did nothing to diminish such rivalries. Indeed, they intensified as the economic and social problems of demographic growth, industrialisation, as well as the ideological and political challenges to the old social order found expression in totalitarian ideologies of both left and right, which seeded the world wars of the 20th century.

Yet through all the cuts and thrusts of international politics, Europeans have sought to control and even eliminate their destructive and often murderous rivalries by making formal attempts to end individual conflicts. These efforts were aimed at redressing the sources of a conflict containing the violence inherent in inter-state rivalries and regulating the behaviour of combatants in wartime. The amicable functioning of commercial and social relations was to be ensured and individuals and groups were to be protected in a transnational context. However, these treaties differed in the extent to which they reflected and even reinforced the "anarchic" international order in which the contracting parties were operating or sought to break with the past and to recast the system and the conduct of relations within it.

Treaties and Alliances in the "Anarchic" Order

General peace treaties that tried to settle the entire European order are particularly revealing in this respect. They include the Peace of Westphalia in 1648, the Congress of Vienna in 1815, the Paris Peace Conference of 1919 and the peace settlement in Europe in 1945. All these treaties reinforced the principle of sovereignty, but 1648 did so perhaps more than all the others. Although the assertion of state sovereignty was partly a contemporary response to religious conflict and an effort to relegate such matters to the domestic legislation, the "Westphalian system" – one based on the "anarchic" action of independent states – is still thought of as the foundation of international relations today.¹² The treaties all realigned territorial arrangements as a means of recognising new power relationships or of restraining the expansionism of certain states. The former goal was relevant in 1815, when Russia held sway over the Congress Kingdom of Poland and in 1919–1920, when the collapse of the empires of Central and Eastern Europe was effectively ratified by recognising the successor states. The latter was the purpose behind the creation in 1815 of the United Netherlands and the aggrandisement of Prussia in Germany and Austria in Italy, which sought to buttress Northern and Central Europe against the possibility of a resurgence of French military power. It was also one of the goals of the division of Germany in 1945. Yet peace treaties such as these, all of which ended general European bloodbaths, may make adjustments to an international system or even recast it completely, but the manner in which a treaty system operates is shaped by the attitudes, assumptions and perspectives of the political actors who work within it. Arguably, any international order can survive and maintain peace and security if its constituent parts show restraint and a willingness to cooperate within it¹³ but this is unlikely to remain so for long, since rulers or public opinion within the defeated states may feel aggrieved or affronted by the peace settlement and so become "revisionist" powers – meaning that they want to revise the terms of the treaty. This includes France after 1815, Germany after the Versailles treaty in 1919 and Hungary after the Treaty of Trianon in 1920. Moreover, no general peace treaty can anticipate, let alone control, the direction of long-term political, social and cultural developments, either within the contracting parties or globally, so that even states that once acquiesced in the international order might grow restive within it. If, for example, one accepts the view that nationalist ideas were neither as deep nor as widespread in Europe in 1815 as was once thought¹⁴ they did subsequently spread. The international system as established at Vienna in 1815 was eroded over the next sixty years by the emergence of nationalist movements and the subsequent demands and achievement of national unifications, as well as by the pace of economic growth and the movements for greater social justice, which often had revolutionary consequences.

In these fluid circumstances, the longevity of any treaty system depended to a large extent on the willingness of the separate states to be flexible in the face of new challenges and to show strategic restraint when confronting new circumstances and opportunities. Most states, however, have at some time in the past been tempted to use violence or the threat of violence in order to enhance their position within the international system. Yet other responses have included forms of international agreement aiming to preserve peace and security within the treaty system. Thus, the Congresses of Cambrai (1724–1725) and Soissons (1728) were attempts to resolve problems arising from the peace of Utrecht in 1713. The Congress System envisaged by the great powers in 1815 was intended to meet in order to discuss and to resolve problems of mutual interest; the Congress of Berlin in 1884–1885 sought to control European imperial rivalries in Africa; the Locarno agreements of 1925 aimed at guaranteeing the international borders in Western Europe and so ease tensions arising from some of the territorially more punitive clauses imposed on Germany in the Treaty of Versailles. Yet some such agreements might go beyond mere adjustments of the treaty system, but reverse and indeed inadvertently damage it. The Munich Agreement in 1938 – applauded though it was by many relieved Western Europeans as a fresh chance for peace[] – surrendered the territory of a sovereign state recognised at the Paris Peace Conference and may have encouraged Nazi expansionist ambitions. Moreover, it was one of the spurs driving the Soviet Union into an accommodation with Germany in 1939, sealing the fate of other sovereign states, namely Poland, Estonia, Latvia and Lithuania.

Alliances are also agreements that may help or hinder the flexibility of an international treaty system, depending upon their purpose. Within an "anarchic" balance of power system, an alliance might be used to restrain the ambitions of a potential hegemon or of a "revisionist" power. The Quadruple Alliance of 1718 between France, Britain, Austria and the United Provinces sought to forge a cordon against the expansionist designs of Spain under Philip V. (1683–1746); the Quadruple Alliance of 1815 between Britain, Prussia, Austria and Russia was aimed specifically against any resurgence of French power after the Second Treaty of Paris. In 1921, the "Little Entente" of Yugoslavia, Czechoslovakia and Romania was forged to contain the possibilities of revisionism by Hungary, truncated after the Treaty of Trianon in 1920.¹⁵ Yet alliances might also be used for aggressive purposes. A criticism of the balance of power system as it operated after 1648 was that alliances were used not only for mutual security, but also to aggregate the capabilities of the allies for expansionist designs. 18th-century critics of the "anarchic" system argued that alliances were merely temporary armistices, the instruments of princely ambition rather than forces for stability and all too often secret.¹⁶ All this had an element of truth. After 1648, alliances were often explicitly limited to a certain period of time and were contracted for specific goals, including the compensations and indemnities to be divided amongst the allies after the anticipated war and their obligations during the conflict, right down to how many and what kind of forces would be committed by the allies. Moreover, offensive clauses were often kept secret or discreetly made in additional protocols. Alliances that were usually justified on the grounds of the European balance of power could equally be ruptured for the same reason: if an ally grew too powerful, then the breaking of an alliance was considered not only fair but beneficial, since it helped to redress the balance of power. Such logic helps explain some of the breath-taking diplomatic "revolutions" of the 18th century, perhaps most notable of which was the Franco-Austrian alliance of 1756, in which the two longstanding enemies realigned themselves against their erstwhile allies, respectively Prussia and Britain.¹⁷

This, at least, suggests that there was some flexibility in the "anarchic" system as it operated in the 18th century, but by the early 20th century, alliances appeared to function in exactly the opposite way. On the eve of the First World War, the defensive alliances and understandings that bound together the central and entente powers appeared to leave little or no room for manoeuvre as the July crisis in 1914 unfolded at breakneck pace, giving rise to the contention that the alliance system may have been a cause of the conflict. Yet it can be observed that ultimately governments still had to make the decision to go to war. To cite three examples, Germany was under no treaty obligation to assist Austria-Hungary militarily against Serbia, at the very start of the crisis, but only to provide "benevolent neutrality"; the British were under no obligation to assist France or Russia, but rather they entered the conflict because they were signatories of the Belgian neutrality treaty of 1839; Italy, as part of a defensive alliance with Austria and Germany, was in its rights not to enter the war at all, but by 1915 calculated that its interests were better served by joining the Entente powers.

What seemed particularly dangerous to critics of diplomatic practices was secrecy in international treaties. The Austro-German alliance of 1879 and the Franco-German alliance of 1893 were secret, although in fact the German Emperor insisted on sending a copy of the former to the Tsar in order to prove Germany's defensive intentions. The Non-Aggression Pact between Nazi Germany and the Soviet Union in August 1939 carried a secret Additional Protocol that demarcated the two states' respective spheres of influence, which ran straight through Poland.¹⁸ It is perhaps scarcely surprising that such secret diplomacy met with criticism. The very first of the Fourteen Points delivered in January 1918 by US President Woodrow Wilson (1856–1924)[] was that the only basis for international relations could be "open covenants of peace, openly arrived at, after which there shall be no private international understandings of any kind but diplomacy shall proceed always frankly and in the public view".¹⁹ Indeed, the Covenant of the League of Nations in 1919 attempted to make all international agreements open and transparent, by declaring that no international agreement between states would be binding until it was registered with the League's Secretariat (Article 18).²⁰ This clause was echoed in Article 102 of the 1945 UN Charter: "No international agreement can be cited before the UN unless similarly registered".²¹

Experiments in Hegemony

The examples of treaties and alliances discussed so far were all based on the assumption that the contracting parties were sovereign states and that, while surrendering some of their freedom of action in entering such agreements, they were still able to pursue their own interests. Indeed, the preamble to the United Nations Vienna Convention on the Law of Treaties in 1969 assumes "the sovereign equality and independence of all States" in the making of international agreements. Yet this has not always been the case in the European past. Periodically, treaties and alliances were made in a way that suggested a push towards a "hegemonic" system, away from an "anarchic" one. Such international systems could operate in a variety of ways and intensities. Alliances where the balance of power diminished the sovereignty of the secondary partner in favour of that of the "hegemonic" state include those which were sealed between the revolutionary France and its "sister republics" in the late 1790s. The latter were invariably compelled to raise armies and taxation to serve alongside the French and to subordinate their foreign policy to that of the French Republic. Such treaties had their imperial equivalents in 18th-century India, where the European trading companies, particularly the French and the British, made subsidiary treaties with local governments, offering military support, including the provision of troops attached to the prince's own army, in return for the annexation of tax-yielding territory.

However, a "hegemonic" alliance could work in ways that actually protected and guaranteed the independence and integrity of the European states. The creation of the North Atlantic Treaty Organization in 1949 can be seen as a projection of the power of the United States, but it also created binding security obligations on all its members, which have not been subjected to "hegemonic" coercion in the same way that France's sister republics or the British East India Company's client states were. Even so, an acute awareness since the end of the First World War that power was slipping away from Europe towards the great powers on the periphery, namely the USA and the USSR, encouraged some European politicians to think in terms of specifically European solutions to cooperation and security. Some saw in the Locarno treaty of 1925 the dawn of a new era of European integration. The dream fell apart under the pressure of the Depression and the rise of totalitarianism, but the Western European dilemma between Atlanticism and forms of European federalism was revived after 1945, in the light of the constructive US involvement in post-war reconstruction (e.g. the Marshall Plan) and the new challenges of the Cold War. The creation by treaty of the Council of Europe, the European Defence Community and even (in 1951) the European Coal and Steel Community were all attempts to encourage international cooperation within Europe, but also ways to counter-balance the potential hegemony of the superpowers.²² Yet this and the forging first of the European Economic Community and then of the European Union were achieved alongside European integration into the NATO. Later, as the NATO expanded eastwards after the Cold War in the 1990s, it certainly imposed conditions on membership that included democratic reforms and the adoption of market economies, but such conditions served the overarching purpose of the NATO at its inception: to reinforce democratic and market-led institutions while also offering collective security for all its partners. In its structures and its aims, in fact, the NATO lies as close to a "constitutional" alliance as it does to a "hegemonic" one, in the sense that its structures are based on the concept of "institutional binding". By signing the North Atlantic Treaty its members make commitments to mutual defence, strategic restraint and now political and economic reforms that are difficult to retract. Unlike classic "balance of power" alliances, such an arrangement is intended to offer a promise of security over the long term, with shared rules of conduct and rpelations. It falls short of a "constitutional" arrangement in that it does not demand of its members any submission to a higher legal authority.²³

Treaties and Alliances: A Movement towards a Constitutional Order?

Throughout the last four centuries the elements of a "constitutional" order have been seeded in the thinking and practices of European international relations. One response to the emergence of powerful, sovereign states within an "anarchic" international order was the emergence of early modern notions of international law in the 16th and 17th centuries. For Renaissance scholars such as the Spanish Dominican friar Francisco de Vitoria (1483–1546), the problem was how Europe would ever know lasting peace if there were no checks on the absolute sovereignty of rulers and their states.²⁴ Hugo Grotius (1583–1645)[] in De Jure Belli ac Pacis (1625) grasped this nettle. While both Vitoria and Grotius argued that the law of nations (jus gentium) was based on natural law and so pertained to all peoples and all states, Grotius envisaged a time when all states would agree on a law of nations, based on a contract between them which, if it could not preserve perpetual peace, would at least govern the opening and conduct of war. The ideas of international law or of a European – indeed worldwide – system governed by international institutions were developed, debated and taken up over the following two centuries by lights such as William Penn (1644–1718), Gottfried Leibniz (1646–1716), John Bellers (1654–1725), the abbé Charles-Irénée Castel de Saint-Pierre (1658–1743), the abbé Gabriel Bonnot de Mably (1709–1785), Jean-Jacques Rousseau (1712–1778), Emmerich de Vattel (1714–1767) and Immanuel Kant (1724–1804)[]. Yet the fundamental problem remained how to establish a system of international law that would overarch the sovereignty of the separate, sovereign states – and their alliances.

Of all the writers cited, the abbé Mably and the Swiss jurist Vattel concentrated on regulating the relations between states rather than conceiving of a full-blown "constitutional" system – Mably in the Droit Public de l'Europe (1746), Vattel in the Droit des Gens (1758). Like Grotius, Vattel did not envisage a system of law that would eliminate conflict, but hoped instead states would agree on international practices and regulations governing the conduct of relations between states, particularly in times of war. The droit des gens – the law of nations – consisted of such agreed customs and rules. Vattel emphasised that all states, of whatever size, were equally sovereign and had the right to defend their independence, but not to assail the liberty of others. For Vattel, there were three types of the droit des gens. There was what he called the "customary law of nations", namely "certain maxims, certain practices, consecrated by habit, and which Nations observe amongst each other as a kind of Law…founded on tacit consent". The other was the "Conventional Law of Nations", meaning that which arose from existing treaties. Since all treaties only served to impose obligations on the contracting parties, their provisions could not be universally applied but only formed part of international law for the contracting parties. "All that can be done on this matter", Vattel concluded, was to forge the third kind of law of nations, that of treaties, which would "establish general rules which Nations must observe in relation to their treaties". ²⁵

It was this last challenge that Mably had already taken up. His work contrasted with Vattel's in that he sketched out international law as it existed on paper at the moment, not as it might become. His work was primarily a collection of all the most important political and commercial treaties since the Peace of Westphalia in 1648, pointing his readers to what he called the droit public of Europe – the complex of international agreements that had grown up around them over the previous century. Mably did follow this up a decade later with a treatise on the principles upon which international diplomacy should be conducted.²⁶ Yet the contrast between Mably's main focus and that of Vattel is that, while Mably's droit public was essentially the entire body of existing international agreements which would form the legal framework for the conduct of international relations, Vattel's droit des gens placed more emphasis on how such relations, and particularly warfare might or ought to be operated within such a framework.

The significance of the work of these two contemporaries was that together they sketched out two, not necessarily conflicting perspectives on the role of international agreement in limiting and restraining aggression and of containing the use and effects of violence in times of war. Their ideas and those of Grotius, among others, have helped shape the legal concepts of international law, treaties and agreements ever since. At any given point in time, the body of treaties and international agreements in force were a source of international law – Mably's droit public, a legal framework for the conduct of international relations – or they may be used to codify or regulate existing practices and behaviour in the day-to-day conduct of relations between states within that legal framework – Vattel's droit des gens. In both purposes, the essential element in the process of making treaties was that they were based on the reciprocal agreement of all the parties. Moreover, like Vattel and Mably, the UN Convention assumes that international law is based on an as-yet unspecified combination of pre-existing treaties, "the rules of customary international law" and an overarching law of treaties which, it is to be hoped, would be progressively developed and codified to promote peace, security and friendly relations between nations.²⁷

In any case, two developments that accelerated in the 19th century coalesced to focus European minds on new forms of international agreement and cooperation that went beyond the customary, power-political concerns of treaties and alliances. The first was European industrialisation and economic growth, which both increased competition amongst the states and forged together national, European and indeed global markets in a web of inter-dependency with new, faster forms of communication and economic specialisation. It also made warfare more destructive and murderous with the development of new military technologies. These developments drove governments to new forms of agreement on international regulation and legislation. The second factor fused with the practical concerns arising from an industrial and later post-industrial world: the growth of public opinion, expressed in the rapidly-evolving organs of civil society. Public opinion was not necessarily pacific, let alone pacifist. Indeed the modern European past is littered with examples of aggressive forms of nationalism expressed at the grass roots. Yet governments also increasingly understood the necessity of persuading people of the justice of their international policies, whether peaceful or aggressive. While nationalism and national interests always underpinned many of these justifications, so too did appeals to civilisation and justice. These sentiments were sharpened by the horrors of two World Wars, including genocide, which provoked enough of a groundswell of public revulsion to make politicians seek new forms of international treaty and alliance in the 20th century.

The 19th and 20th centuries therefore witnessed a wealth of treaties aimed at easing the transnational movement of goods, people and knowledge, as well as to mitigate some of the effects of warfare on combatants and civilians alike. Individually, many of these treaties were relatively anodyne, but collectively, they represented a most significant surge in international agreement. The Red Cross organisation was created in 1864; ten years later, the General (later Universal) Postal Union was established with its headquarters in Berne in 1874 to introduce standard regulations on the international delivery of mail. Its members agreed to submit to arbitration in the case of disputes. Other international agreements – and there were no fewer than 23 between 1875 and 1919 – concerned the telegraph, transport, public health, armaments and the use of explosives.²⁸ The wartime treatment of civilians, of prisoners of war[] and of sick and wounded combatants was the subject of the Geneva Conventions in 1864, 1906, 1929 and 1949. The Final Act of the International Peace Conference at The Hague in 1899 published international agreements on the peaceful resolution of international disputes, on the conduct of war on land and sea and on adapting the laws of maritime warfare to the Geneva Convention of 1864.²⁹ It also issued three declarations banning aerial bombardment, poison gas and dumdum bullets.

This plethora of international legislation brought Europe closer than ever before to a "constitutional" order, but it was a legal order without any overarching, let alone binding, institutional architecture. The horrible experiences of the two World Wars, however, prompted more forms of international agreement that moved a little closer towards a "constitutional" order, but one still based essentially on the sovereignty of independent states. The League of Nations, created by the international Covenant of 1919, and the United Nations, founded by the international Charter in 1945, continued to recognise sovereign states as the very foundation of the international order: the very first principle of the United Nations Charter, for example, is that the organisation is "based on the principle of the sovereign equality of all its Members".³⁰

Yet both the League and the UN – combined with other international agreements such as the Bretton Woods agreement in 1944 establishing the International Monetary Fund and the International Bank for Reconstruction and Development (now the World Bank) – represented an attempt to temper the "anarchic" international order. International treaties and alliances had clearly failed to prevent the two successive (and progressively more violent) bloodbaths of the First and the Second World War, so the Covenant of 1919 and the Charter of 1945 represented forms of international agreement that would overarch, but not intrude on, the sovereign states of the world. They aimed at establishing a formal security architecture that would actively encourage international arbitration and discourage the resort to war. The goal of restraining states from violence, but also recognising their essential independence, was a balance that proved and still proves difficult to strike.

Both the Covenant of 1919 and the Charter of 1945 insisted that their members adhere to certain guiding principles in the conduct of their international relations. Members of the League agreed "not to resort to war", to engage in "open, just and honourable relations" with each other, to abide by "international law as the actual rule of conduct among Governments" and to maintain justice and "a scrupulous respect for all treaty obligations". Article 8 bound all Members to talks about the reduction of armaments, armed forces and of the manufacture of arms. In Article 12 it was decreed that members undertook not to resort to war until their dispute had been submitted to the Council or the Court of International Justice (which was established by Article 14). Moreover, while the League of Nations explicitly eschewed intervention in the internal affairs of states, it did have oversight of the 1919 Minority Rights Treaty, which (its critics contended) infringed state sovereignty.³¹ Article 2 of the UN Charter obliges its members to settle their disputes by peaceful means "in such a manner that international peace and security, and justice, are not endangered". Furthermore, it demands that all members refrain from threatening or using force against the independence or integrity of any state, as well as committing its members to a raft of forms of international cooperation in a drive for higher standards of living, economic and social development (Article 55):

solutions of international economic, social, health, and related problems; and international cultural and educational cooperation and universal respect for, and observance of, human rights and fundamental freedoms for all without distinction as to race, sex, language, or religion.³²

The emphasis on human rights in the 1945 Charter differed from the 1919 agreement in that it emphasised individual rights, rather than the collective rights of national or ethnic groups, as the 1919 Minority Rights Treaty did. This was because the emphasis on collective, ethnic rights had proven to be a source of conflict in the inter-war period, justifying irredentist claims in Central and Eastern Europe.

The UN Charter is more robust in its determination to override state sovereignty in matters of international peace than the League of Nations Covenant. Members of the League of Nations theoretically committed themselves to the superior jurisdiction of an international body, whether the Council or the Court, but in practice the essential freedom of action by individual states was preserved by the League's procedures. It was up to the individual members of the League to bring disputes or threats to peace to the attention of the Council (Article 11), while the UN Charter empowered not only individual members, but also the Security Council (Article 34) to bring threats to international security to the attention of the General Assembly and to investigate them of its own accord. In the League, if (as was likely) the Council failed to reach a unanimous ruling, Article 15 left it up to the individual members to "take such action as they consider necessary for the maintenance of right and justice", while the UN Charter empowers the Security Council to do the same, including the use of military force (Articles 41, 42). Moreover, decisions of the Security Council are binding on all members (Article 25) and, while the UN's seventh guiding principle (in Article 2) is that it has no right to intervene in the domestic affairs of any state, this is with the caveat that "this principle shall not prejudice the application of enforcement measures" decided by the Security Council. Under the Covenant of 1919, while economic sanctions would be automatically imposed on states that broke their international obligations (Article 16), the use of force by the members of the League to compel compliance could only occur on the unanimous decision of the Council. Meanwhile in the UN Charter (Article 27), the Security Council's decisions need only an affirmative vote of 9 of its 15 members, with unanimity or abstentions of the five permanent members.³³

Even so, by including such matters as rights (whether collective or individual), by insisting on the self-determination of all peoples and in their determination to address matters of common concern,³⁴ both the Covenant of 1919 and the Charter of 1945 in some respects built upon the wealth of international agreements that had risen since the second half of the 19th century. Yet they went further, by creating an institutional architecture in which these concerns might be addressed. This represents a major leap forward from earlier concepts of what international treaties were for: the maintenance of peace and security by addressing the structural problems of international relations.³⁵ Yet the Covenant and Charter related the wider questions of cooperation on economic, social and cultural matters to this very issue. While they still regard the sovereign state as the fundamental, legitimate actor in international relations, they were sophisticated attempts to address the complex interaction between the different pressures that led to conflict. They were based on an understanding that no modern international system, no peace, can last unless it maintains not only peaceful relations between states, but also meets public demands for legitimacy and welfare.³⁶ In their robust recognition of the essential sovereignty of all member states, the League of Nations Covenant and the United Nations Charter fell deliberately short of creating a full-blooded "constitutional" order, even though there are strong elements of such an order written into the agreements. So while they would not realise the dreams of global governance envisaged by such visionaries as Saint-Pierre, Penn or Rousseau, they might – at least in their intentions of submitting the "anarchic" international order to legal forms and procedures – have pleased the likes of Grotius, Vitoria and Vattel.

Michael Rapport