The European Union has been described as ‘the greatest peacemaking project in history’ and as a ‘sophisticated institutional expression of anti-imperialism’. Neither claim entirely exhausts the objectives of the union, but they do sum up its two most salient features. In what follows I shall attempt a historical reflection on both.

To begin with the first: in 1888, the great English jurist, Henry Sumner Maine, in one of the earliest series of lectures ever delivered on the topic of international law, observed that ‘war appears to be as old as mankind, but peace is a modern invention.’ But how do you invent peace? To put it briefly (and very crudely), there would seem to be two possible answers. Either, all the potential combatants are subsumed under one single power which maintains the peace by force. Or, all agree to combine their various capabilities in such a way as to ensure that no one power has ascendancy, or any incentives to acquire any ascendancy, over any other. The first solution is, of course, an empire. The second is a federation. Both can take many forms. And as the case of the Delian League of the fifth century BC, which rapidly transformed itself from a federation intended to protect the Greek city states from the Persian Empire into the Athenian arche, served as a constant reminder, the latter could easily become the former.

It was, of course, the Roman Empire – in particular, in the Age of the Antonines, the age of the Five Good Emperors as they have come to be known (from Nerva to Marcus Aurelius)– which, it could be said, first brought some measure of stability and peace to Europe. It may not quite have been, in Edward Gibbon’s words, ‘the period in the history of the world during which the condition of the human race was the most happy and prosperous’, but it certainly came closer, if not for the human race as such, then certainly for Europe, than had any previous period, or indeed any subsequent one for many centuries to come.

And as a project for unification it was a resounding success. From northern Britain to north Africa, from Spain to what is now Syria and Iraq, local elites adapted themselves to Roman ways of life. For its most skilful and most fortunate subjects, the empire became a vast resource, hugely more enriching than the narrow limits offered by the original communities from which they came. Living in Roman villas, they took up Roman dress, Roman customs and the Latin language and, in time, they came to think of themselves as Romans. We do not know how much of the older pre-Roman world survived Romanisation, but it is remarkable that we do not know. Almost no trace now remains of any pre-Roman literature, oral or written, or of any pre-Roman history of the peoples at the heart of the empire in the western Mediterranean and northwestern and central Europe. Below the level of the urban aristocracy, the older ways and earlier languages must have survived. Several Celtic languages, some of which, in some version, survive to this day, must have gone on being spoken throughout the nearly four centuries of the Roman occupation of Britain. But if so, they have left no written trace. The only language to survive Romanisation was, of course, Greek; and Greek was the second language of the empire, the language which every cultured Roman patrician spoke and the language of the administration of what would become, after Diocletian divided the empire in the late third century, the Empire in the East.

But the pax Romana could never be repeated. After the collapse of the Roman Empire in the West and the subsequent demise of its self-declared successor, the Carolingian Empire, at the end of the ninth century, no one – despite Dante’s lingering hope that the Holy Roman (and German) Emperor would be able to united all of Europe under one ruler – really imagined that an empire would be capable of bringing lasting peace to Europe. Most of the petty kings of Europe adhered to the idea of the canonists that, whatever the status of the Emperor might be, each of them was an ’emperor in his own kingdom’: rex imperator in regno suo. The only would-be successors to Rome who really intended to unite Europe under one rule (their own) – Napoleon and Hitler – failed to take to heart the Roman historian Livy’s observation that ‘an empire remains powerful only so long as its subjects rejoice in it.’

That leaves federation. The earliest sustained and serious suggestion that only a union of European states would be capable of bringing about a lasting peace was Eméric Crucé’s New Cyneas of 1624. This laid out plans for a permanent peace conference to be held in Venice, a convenient gateway, geographically and culturally, between Christianity and Islam, the two warring power blocks of the early-modern world. All the nations of the world, including the Ottomans, would be represented. The Pope would be the president and the Sultan his deputy. There was to be a common currency and free trade – a kind of early outline, as some have seen it, of the European Union, extended eastwards to include Europe’s oldest and, in the mid-seventeenth century, still its most deadly enemy. The better known Grand Design of about 1640 by the Duc de Sully (with perhaps some input from Henri IV of France) was, similarly, an attempt to reorder the current balance of powers. It was intended to create a ‘very Christian’ and peaceful republic, ruled over (insofar as its international relations were concerned) by a series of councils.

Practically, it was a fantastical proposal which involved the territorial redistribution of Europe into six hereditary monarchies, five elective ones and four republics, making the Pope into the sovereign of most of Italy and ceding Sicily to Venice. All of this would be governed by what Sully called ‘le conseil général de l’Europe‘ and which, significantly, he likened to the ‘Amphictions of Greece’. (These leagues of the Greek city states were the model used by Immanuel Kant for his ‘league of peoples’ and by James Madison for the future United States.)

Both the New Cyneas and the Grand Design were written during the Thirty Years War and both were offered as thinly veiled attempts to find a resolution to the religious conflicts which had convulsed Europe for over a century. The Treaty of Westphalia, which brought the Thirty Years War to an end in 1648, pointed however towards a very different future for the continent – what came to be called the ‘Europe of Nations’, based upon a Hobbesian idea of the nation as a single body of people, with a single religion and a single source of sovereignty. While this could, and did, resolve the religious conflicts of which the Thirty Years War had been the last and most devastating, it offered no prospect for an end to warfare as such. The Franco-Dutch War followed between 1672–78; the War of the Spanish Succession between 1701–14; the so-called War of Jenkins’ Ear from 1739–48; the War of the Austrian Succession between 1740–48; and between 1756–63, the Seven Years War, the bloodiest of them all and, as it raged from Pomerania to India, arguably the first true world war. The concept of undivided sovereignty which had served to end one kind of conflict would seem to have only exacerbated all others. This vision of sovereign power – in the telling phrase of the seventeenth-century French jurist, Cardin Le Brett, ‘as indivisible as a point in geometry‘ – has remained the major intellectual obstacle in the path of European unity from that day to this.

At the same time, however, Europe came increasingly to be looked upon not merely as a collection of sovereign nations but as a single, albeit varied, ‘republic’. The idea of a secular, territorial and cultural analogue to the Church’s conception of the ‘Christian republic’, as Giulia Sissa has pointed out, had been familiar to humanist intellectuals since at least the late fifteenth century; and the eighteenth-century conception of a ‘republic of Europe’ was a projection into an imaginary political space of the Renaissance ideal of a republic of letters. By the mid eighteenth century, it had become something of a commonplace to describe Europe in Voltaire’s terms as a ‘kind of great republic divided into several states’. Even Edmund Burke, despite his attachment to what he called ‘the little platoon we belong to in society’ and contempt for the idea that there might exist a universal category called ‘man’, to which rights might be ascribed, believed in the existence of a common European legal culture, based upon ‘the old Gothic customary [law]… digested into system and disciplined by the Roman law’ so that, in its day, it had become ‘virtually one great state having the same basis of general law, with some diversity of provincial customs and local establishments’. For this reason, he added: ‘No European can be a complete exile in any part of Europe.’

The question, then, was how to transform these high-minded perceptions of ‘unity in diversity’ – to use the EU’s own motto – into a political system capable of bringing to an end the internecine conflicts of the European states.

As it became increasingly apparent that the Treaty of Westphalia had not, in fact, brought an end to warfare, a number of suggestions were proposed as to how to establish a truly lasting peace within Europe, all of which recognised that the security of the continent could only be achieved through the creation of some kind of union, which implied, at least, the idea that sovereignty could become divisible. These included William Penn’s An Essay towards the Present and Future Peace of Europe of 1693; the Declaration for a Lasting Peace in Europe by the ‘Old Pretender’ (known to his followers as King James III of England and VIII of Scotland) of 1722; Voltaire’s On Perpetual Peace of 1770; the Scheme of A ‘Perpetual Diet’ for Establishing the Public Tranquility of 1736 (which was more of a proposal for conquering the Ottoman Empire) by Giulio Alberoni, skilled social climber and cardinal in the service of Philip V of Spain; the Project of Perpetual Peace between the Sovereigns of Europe and their Neighbours by a former galley slave, Pierre-André Gargaz, which so impressed Benjamin Franklin that, in 1782, he printed it on the press he had set up on his estate at Plassy, outside Paris; and Jeremy Bentham’s A Plan for an Universal and Perpetual Peace of 1789, which called for the dissolution of the European overseas empires, which he denounced as ‘violations of common sense’ and ‘bungling imitations of miserable [Greco-Roman] originals’.

Most, and certainly the most lastingly influential of these projects, owed rather more than their titles to a bulky, ponderous work by Charles-Irénée Castel, abbé de St-Pierre, A Project for Establishing Everlasting Peace in Europe, written in 1713. St-Pierre was, in many respects, a remarkable and remarkably prescient man. A diplomat who had been a negotiator of the Treaty of Utrecht in 1712–13 and had been expelled from the Académie française in 1718 for denouncing the rule of its patron, Louis XIV, he devised plans for a graded tax system – virtually unthinkable in the early 18th century – and for free education for all, both men and women.

As he saw it, in the current state of Europe, the only possible future was ‘an almost continual state of war interrupted by a number of treaties, or rather cease-fires’. The sovereign powers of Europe, as they were currently constituted, were no different, he said, from ‘the little kings of Africa, the unhappy Caciques, or the little sovereigns of America’. There existed among them nothing which could be described as a ‘sufficiently powerful and permanent society’. The closest they had come was the Swiss Federation or the states of the Netherlands. The problem, as he saw it, was that the ‘balance of powers’ in post-Westphalian Europe was incapable of ensuring the lasting validity of any kind of treaty. In this respect, Westphalia, although far more ambitious and more effective, suffered from the defects of all previous (and subsequent) treaties in that it left the political organisation of Europe unchanged. None of the promises made by one power to another could have any lasting force if they were not subject to what St-Pierre called ‘perpetual arbitration’. And for that to happen, there had to exist a mechanism for constant negotiation; and this would inevitably require the states of Europe to submit themselves willingly to some kind of supra-national authority.

On this assumption, St-Pierre envisaged a future European federation, which he prophetically called ‘the European Union’. St-Pierre’s union, leaving aside his assumption that France and Austria would forever remain the European super-powers, has certain things in common with the present one. It, too, would be created by means of a treaty, but one which would be subject to constant re-evaluation. It was to be equipped with a ‘European Court of Arbitration’ that has some of the features of the European Court of Justice. The external affairs of each of its member states would be governed, not by a single sovereign, but by a council or diet, on which the princes of every member state would sit. This, St-Pierre believed, would eliminate warfare from the continent forever and bring the greatest happiness to the greatest number by finally demonstrating to princes that their true interests lay not in conflict, but in what he called bienfaisance – a term which he seems to have invented – or ‘beneficence’, which was an expression of the sympathy which all human beings were supposed, as individuals, to share with one another. He also believed that such a union would bring an end to what David Hume had called ‘the jealousy of trade’, that ‘narrow and malignant opinion’ in Hume’s words, which led all states that had made ‘some advances in commerce… to look on the progress of their neighbours with a suspicious eye, to consider all trading nations as their rivals and to suppose that it is impossible for them to flourish, but at their expense.’ And when that happened, commerce would finally, in St-Pierre’s opinion, become ‘universal, free, equal, certain and perpetual among all nations’.

All of this was greeted by most of St-Pierre’s readers with a mixture of incredulity and derision. It was, said Voltaire, ‘a chimera which could no more exist among princes than it could among elephants and rhinoceroses, or wolves and dogs’. Gottfried Wilhelm Leibniz, ironical as ever, remarked that it reminded him of a ‘device in a cemetery with the words: pax perpetua; for the dead do not fight any longer, but the living are of another humour; and the most powerful do not respect tribunals at all.’

The one person to take it seriously was Immanuel Kant. In 1795, he wrote what became perhaps the most widely influential text on the possibility of a world, or at any rate European, peace-federation in the post-Napoleonic period: Toward Perpetual Peace: a Philosophical Sketch. It has been seen as the inspiration behind both the League of Nations and the United Nations and as a foundational document in the rise of the new international law in the mid-nineteenth century and in the new discipline of international relations. It was even cited as an inspiration by Mikhail Gorbachev in his acceptance speech for the Nobel Peace Prize in 1990. But although Kant’s objective was to secure a world peace his most obvious intellectual beneficiary has been the EU.

In Kant’s view, although St-Pierre’s project may have been ‘ridiculed by great statesmen, and even more by heads of state, as pedantic, childish and academic’, its basic claim, that perpetual peace, within Europe or beyond, could only be brought about by some kind of federation, was inescapable.

Like all previous projects for European unity, however, St-Pierre’s suffered from one basic flaw. Like them, it left the existing regimes within Europe as they were. Unity, that is, was to be a matter of the direct application of law. For Kant, however, it was obvious that, in order for states to enter into what he called an ‘international civil constitution’, they would all have to adopt the same kind of political regime; and not just any regime, but the only one which, in his view, would ultimately make such a constitution appealing to all states. This he called the Representative Republic, or what we today would call a liberal democracy. Its crucial features were to be representation and the division of powers. Only these would ensure the two fundamental rights of citizens, which were (a) the privilege not to obey any external laws except those to which the citizen could have given consent and (b) that no citizen can be bound by law, unless all are subject to it simultaneously and in the same way.

However, it was clear to Kant that some states (France, in particular after 1789) were better suited to becoming representative republics than others. In order to assure perpetual peace in a world where not every state is a liberal democracy, those that are must enter into a lasting union with one another. Furthermore, since the external and internal affairs of states are inextricably linked, this gave each state a right in the interests, not of moral priority, ‘but only of security’, to ‘demand of the others that they enter along with it into a constitution similar to the civil one, within which the rights of each could be secured.’

Kant stopped short – as indeed have all the subsequent political theorists of European federalism – of dismissing what Altiero Spinelli in 1941 called ‘the absurd principle of non-intervention’, as if ‘every internal constitution of every European state taken in isolation was not of vital concern to all of the other member states’. And he never supposed that ‘representative republics’ had the right to impose their constitutional forms on any other. Unlike the European order established at Westphalia in 1648 and again (with considerable modifications) at Vienna in 1815, Kant’s ‘international civil constitution’ would not be based on a balance of power between states exercising individual and indivisible sovereignty; nor would it in any way be an empire – or, to use the language of the day, a ‘universal monarchy’. These, in Kant’s view, were unnatural creations doomed to collapse into anarchy once they had crushed all ‘the grams of goodness’ from their hapless victims. ‘Nature’, as he put it succinctly, having conveniently separated all the peoples of the world by language and religion, ‘wills it otherwise.’

The terms Kant used to describe his federation – a ‘league of peoples’, ‘an international state’, a ‘universal union of states’, a ‘federation’, a ‘confederation’, a ‘partnership’ – are many and confusing, but whatever else it might be, it would be a peaceful, consensual body and all those who joined it would do so because they perceived it to be in their particular interests and, of course, they would do so of their own volition. The effect would be not to erase those differences which had hitherto been the cause of war, but with ‘increasing culture and the gradual approach of human beings’ lead to a ‘greater agreement in principles’. It would finally result not, as all empires had, in the ‘weakening of all forces’, but in ‘their equilibrium in liveliest competition’.

The question, then, was how to bring this about. The European states (or at least some of their citizens) already had a sense of themselves as belonging to some kind of political and cultural union larger than the nation; and their sheer proximity to one another seemed to many to make their eventual union inescapable. As Alexander Hamilton had already seen in 1788: ‘To look for a continuation of harmony between a number of independent, unconnected sovereignties situated in the same neighbourhood would be to disregard the uniform course of human events and to set at defiance the accumulated experience of ages.’ Harmony could only be achieved by means of some form of integration.

Hamilton was, of course, talking about the fledgling United States, a group of sovereignties united by a common language, a common religion and a common political culture. But he was certain that, sooner or later, the same logic would come to apply to Europe. For Kant, too, to resist union would be to deny the evidence of history, although his was a very different kind of history to Hamilton’s. But the purely human instrument which would finally persuade all the states of the modern world to unite was – as it had been for St-Pierre – commerce. ‘The spirit of commerce’, Kant wrote, ‘sooner or later takes hold of every people; and it cannot exist side by side with war and, sooner or later, this spirit dominates all people. For among all those powers (or means) that belong to a nation, financial power may be the most reliable in forcing nations to pursue the noble cause of peace (although not from moral reasons).’ A true union, then, would be one of commercial nations, united in the common commitment to the fundamental rights of their citizens and bound together in their own interests for reasons of security.

Kant provides no specific suggestions as to how this would be achieved. Two things, however, were clear. First, only a union driven initially by the economic cooperation between liberal states could bring about a condition which, while it was based upon the observation of existing state boundaries and cultural identities, would nevertheless involve the voluntary division of sovereign power between the federated states. And second, only such a federation would be capable of achieving the kind of progress to which, in Kant’s view, humanity was inescapably committed whether it liked it or not. Or, to put it differently, and setting Kant’s metaphysics aside: this was the only possible modern international order.

All of this was, of course, swept away by Napoleon and by Napoleon’s vision (if it can be described as such) of what he called the ‘great family of Europe’, united as a new kind of French empire and by the rise of a new kind of nationalism after 1815, which sought to merge an earlier conception of the patria, as a devotion to ‘laws and liberty’, with a quasi-mystical sense of its own identity as a people. For the new nationalists, the post-revolutionary nation state was, as Hegel said of it, a ‘wholly spiritual entity’ and a ‘spirit in its substantial rationality and immediate actuality and is therefore the immediate power on earth’. It relied for its survival on the presence of an ‘other’ alien and hostile and, although that did not require (at least for Hegel) conflict with the ‘other’, conflict was almost certainly bound to occur, as it did with devastating consequences in 1914 and again in 1939.

But the possibility of a union of politically compatible peoples united by commerce would be revived by Benjamin Constant in the aftermath of the Napoleonic Wars and again by the great Austrian economist, Joseph Schumpeter, in the aftermath of the First World War. It would, of course, take a further half century of incessant warfare, by which time Europe had been reduced to the level of exhaustion in which it had found itself in 1648, before something very much like Kant’s ‘Cosmopolitan Right’ would be revived, in the initially unpromising form of the European Coal and Steel Community of 1950 which, significantly, in the words of Robert Schuman – another reader of Kant – would ‘make war not only unthinkable but materially impossible‘.

For all its vicissitudes, the idea – or ideal – of European Union, as both ‘the greatest peacemaking project in history’ and as a ‘sophisticated institutional expression of anti-imperialism’, has had a far longer and more continuous history than is commonly supposed. The European Union is not only the fulfilment of a project towards which generations have been steadily groping; it is also the expression of a distinctively enlightened modern understanding of European culture. Whatever happens in the difficult months or years ahead, it must not be allowed to founder.

This essay originally appeared under the title ‘From the Great Republic of Europe to the European Union: the long history of the idea and the ideal of European integration’ in ‘The Pursuit of Europe: Perspectives from the Engelsberg Seminar’, Bokförlaget Stolpe, in collaboration with Axel and Margaret Ax:son Johnson Foundation, 2012.