One cannot help but feel a certain pessimism in the air with regard to European integration at the moment. At time of writing, the polls in major European countries are frequently topped by Eurosceptics like Jordan Bardella and Alice Weidel [1]. In many non-EU European countries, appetite for European integration appears low: While a recent Swiss referendum, which could have meant an exit from many agreements with the EU in the long term, failed last week [2] the fact that 45% of votes were cast in favor of a radical proposal, and the fact that this result is being celebrated as a success for Switzerland’s European alignment is telling in itself.

Yet one should not overlook that the Europe of today is politically and economically united in a way that would have been difficult to predict a century ago, when Europe was reeling from one World War and heading into another. At the time, thoughts of European political union were usually confined to the dreams of Paneuropeanist cosmopolitans such as Richard von Coudenhove-Kalergi, and the Second World War would cast significant doubt on the prospects of lasting European peace, much less integration. Yet while the emerging Cold War would divide Europe between East and West, it also created geopolitical circumstances that encouraged (Western) European economic integration. In the light of an imposing Soviet bloc in the East, ideas of economic, political and security integration became increasingly attractive, ideas that found significant support from the United States [3].

While much has changed since then, I would like to call particular attention to two events: First, the Hague Congress of 1948, the first major gathering of European politicians and other representatives working towards closer European integration. The Hague Congress ultimately produced tangible results in the birth of the Council of Europe (CoE). Second, the negotiations ahead of the 1991 signing of the Maastricht Treaty, founding the European Union in its modern form. Both of these events have been enshrined in the history of European integration, and both can provide further insight into the role of political organizations in influencing international politics. The Hague Congress saw the prominent involvement of pro-European movements, but ultimately fell short of hopes for a politically united Europe, while the negotiation of the Maastricht Treaty saw similar movements take a much less central role, even though it did bring about substantial further unification. Why did these events go so differently, and what can that tell us about efforts of further integration today? Let us get to the Core of this.

In 1948, the Hague Congress was convened by the European Movement (EM), later known as the European Movement International (EMI). The EM was a somewhat awkward construction: In the aftermath of the Second World War, several organizations aiming to advance European integration were founded, often with strongly differing visions of what exactly this should look like [4]. These organizations included the Union of European Federalists (UEF), with its traditional membership base in France and Italy and a stated goal of advancing “the struggle for a European federation, intended as the fundamental first step along the road towards world federation” [5]. On the other end were organizations such as the British-dominated United Europe Movement (UEM), founded by Winston Churchill and his son-in-law Duncan Sandys, and aiming instead for a forum of coordination and discussion between European countries, but not a federation of them [6]. These movements were numerous, diverse and often not particularly individually influential. The EM aimed to serve as an umbrella organization to coordinate these different movements towards the common goal of European integration [7].

The Hague Congress thus represents a major organizational and political feat by pro-European organizations. The Conference, which Churchill presided over, was not a mere symbolic gathering of the already convinced: It was attended by influential politicians, including former French, Belgian and Polish heads of government and the soon-to-be first postwar German chancellor Konrad Adenauer, alongside observers from the United States and Eastern Europe. It produced concrete results in the form of the 1949 Treaty of London, which would be ratified by most European countries and established the Council of Europe, the first major pan-European international organization [8]. The conception, planning and execution of the Congress was performed by the European Movement and its member organizations, and thus represents a significant example of pro-European organizations successfully influencing the politics of European countries.

It is thus perhaps somewhat surprising that, despite the Hague Congress representing a previously unprecedented success of pro-European activism, its results are somewhat modest when compared to both the aims of most of its participants and later efforts in European integration. As a result of strong British resistance to more substantial forms of integration, the Council of Europe’s power structure took a strongly intergovernmental form [9]. The council of Europe would end up providing an important institution in facilitating discourse and the articulation of common values between European nations, particularly in the area of human rights. However, it would not ultimately provide the overarching political structure for existing organizations such as the European Coal and Steel Community that many attendants had hoped for [10].

It was only several decades later that this larger political structure would be realized: The 1991 Maastricht Treaty would form the legal basis of the European Union, integrating existing European structures, including those of the European (Economic) Community, into a European Union with the aim of establishing a common citizenship, market, currency, foreign and security policy [11].
The motivation behind the Maastricht Treaty laid in an interplay between optimism and uncertainty. On the one hand, following the 1970s and early 80s, which were perceived as largely stagnant by the standards of European integration, the ultimately successful work towards implementing a European single market in the late 80s provided new optimism for further integration [12]. On the other hand, with the end of the Cold War and its geopolitical order, European states found themselves in a position of uncertainty: Concluding that business as usual was not viable in a rapidly shifting world, said states were willing to renegotiate their position within a larger European framework [13].

In comparison to the Hague Congress, it is striking that pro-European organizations such as the EMI or UEF only make a peripheral appearance in the negotiation of the Maastricht treaty. Initial proposals for a treaty further defining and formalizing European Union were advanced by either individual national politicians, such as German foreign minister Hans-Dietrich Genscher, or parliamentary proposals such as the ultimately unsuccessful “Spinelli Proposal”, a pre-Maastricht draft treaty that would have similarly founded a common European state [14]. That is not to say that these organizations were absent from the history of the Maastricht treaty: The EMI served as an important site of discussion, and the Spinelli Proposal was obviously heavily influenced by the ideas of a founding member of the UEF, Italian socialist and antifascist Altiero Spinelli [15]. However, compared to the EM’s central role in the Hague Congress, these contributions appear modest.

It is thus perhaps somewhat ironic that the Maastricht Treaty ultimately provided a more comprehensive and enduring foundation for European integration than the 1949 Treaty of London. Part of this can be explained by the passage of time: Perhaps the European nations of the 1940s, in the aftermath of the most destructive war in human history, were simply not yet ready to partially give up their autonomy in the same way that the victorious and much more deeply entangled Western European economies of the 1990s were.
Indeed, these shifting circumstances may explain part of the difference between these two cases. However, given that the Hague Congress already saw significant Federalist involvement, and that many countries were willing to go further in pursuing integration, there is likely more to this than a lack of political will. I argue that there are two further factors that explain why the Maastricht Treaty was able to achieve further European integration where the 1949 Treaty of London was not, despite the smaller role of pro-European movements: Shifts in the venues available for international discussions between relevant actors, and the bundling of both idealistic and economic arguments for European integration.

The first lies in the international institutional infrastructure of Europe in the late 1980s and 1990s as opposed to that of that of the late 1940s. The Europe of the late 1940s was simply more reliant on organizations such as the EM to facilitate large-scale multilateral discussions and negotiations. There was not yet a European Parliament European Council, even the European Coal and Steel Community was still in its nascency. This means that the exchange of ideas and the negotiation of further integration had fewer formalized venues available, and instead required pro-active organizations such as the EM in order to initiate and maintain negotiations. Countries can shift in their preferences over time, and international institutions can provide structures that last longer than the initiatives of individual governments and ministers [16]. During the negotiations leading up to the Maastricht Treaty on the other hand, those in favor of integration could fall back on existing structures and forums for discussion between European politicians and activists in the form of organs such as the European Parliament. Thus, movements such as the EM or UEF were simply less indispensable in facilitating communication and discussion between relevant actors, and further substantial European integration could be advanced without them taking a central role.

Another reason for the less central role of pro-EU movements such as the UEF in the negotiation of the Maastricht Treaty lies in the kind of arguments required for the latter to receive the support of national governments. Advocates of the Maastricht Treaty were able to effectively bundle two appeals for European integration, one more idealistic, the other economic. The first more idealistic appeal for European integration was centered around a democratic vision of an empowered European parliament and civil society embedded in a more representative European institutional structure. The second argument centered around the economic benefits of a further integration of the European single market and currency union [17]. As the Hague Congress illustrates, previous attempts at closer European integration were often limited by the unwillingness of certain countries, usually the United Kingdom, to give up their autonomy in favor of more idealistic or abstract benefits of European integration. combining these with the prospect of concrete economic benefits, these parties could be persuaded to join further integration efforts.

In this environment, pro-European movements such as the UEF would likely not have been particularly persuasive. Their pitch for European Unity tends to skew more towards the cultural and idealistic end, and actors receptive to those arguments needed little persuasion. Instead, partners such as the United Kingdom required a more pragmatic angle that tended to come from technocratic organizations such as the European Commission, rather than more idealistic advocacy groups.

This is not to erase pro-European movements from the story of the Maastricht Treaty: Their influence on the Spinelli Proposal is notable, and it is unlikely that the Maastricht Treaty would have existed in its current form without these initial proposals. Nonetheless, the existence of institutionalized venues of political discourse and the importance of technocratic arguments in the negotiations of the Maastricht Treaty provide explanations for why these organizations took a back seat at this crucial juncture in European integration.
What does this tell us about Europe today? Two major takeaways. For one, even though we often take them for granted, existing institutions such as the European Parliament can be powerful resources for those wishing to affect political change, as they provide the infrastructure for political networks across Europe. Second, this case highlights that organizations working towards specific goals are not always the most persuasive advocates for these goals. In the case of the Maastricht Treaty, skeptics of European integration were ultimately won over not primarily by appeals to common European values and goals, but by the more immediate promise of economic growth through market integration.

Endnotes:
1. POLITICO. “POLITICO Poll of Polls — European Polls, Trends and Election News.” February 2, 2022. https://www.politico.eu/europe-poll-of-polls/.
2. CNN. “Swiss Reject Population Cap in Referendum, Avoiding EU Clash and Cheering Business.” June 14, 2026. https://www.cnn.com/2026/06/14/europe/swiss-voters-population-referendum-intl.
3. Thum, Gregor. Europa“ im Ostblock Weiße Flecken in der Geschichte der europäischen Integration.” Zeithistorische Forschungen/Studies in Contemporary History, no. 1 (2004): S. 379-395.
4. Hick, Alan. The ‘European Movement’ in Lipgens, Walter, and Wilfried Loth, eds. Transnational Organizations of Political Parties and Pressure Groups in the Struggle for European Union, 1945-1950: Including 129 Documents in Their Original Languages on 3 Microfiches. Documents on the History of European Integration / Edited by Walter Lipgens, Volume 4. Walter de Gruyter, 1991.
5. Pistone, Sergio. The Union of European Federalists: From the Foundation to the Decision on Direct Election of the European Parliament, 1946- 1974. Studi / Centro Studi Sul Federalismo 7. Giuffrè Ed, 2008. Preface.
6. Wassenberg, Birte. Histoire Du Conseil de l’Europe. Editions du Conseil de l’Europe, 2013.
7. Hick, A. European Movement
8. Wassenberg, Histoire Du Conseil
9. Vayssière, Bertrand. “Federalists and the Beginnings of the Council of Europe: Converting Institutions and Opinion to Supranationality (1949–1951).” Histories 2, no. 1 (2021): 1–14. https://doi.org/10.3390/histories2010001.
10. Wassenberg. Histoire.
11. Christiansen, Thomas, Simon Duke, and Emil Kirchner. “Understanding and assessing the Maastricht Treaty.” In The Maastricht Treaty: Second Thoughts after 20 Years, pp. 1-14. Routledge, 2016.
12. Jaeschke, Victor. Eine „immer engere Union“: Konkurrierende Europakonzepte und der Vertrag von Maastricht, 1987–1992. Studien zur Internationalen Geschichte 60. De Gruyter Oldenbourg, 2025.
13. Thomas et al., Maastricht Treaty.
14. Jaeschke, Engere Union
15. Ibid.
16. Shanks, Cheryl, Harold K. Jacobson, and Jeffrey H. Kaplan. “Inertia and Change in the Constellation of International Governmental Organizations, 1981–1992.” International Organization 50, no. 4 (1996): 593–627. https://doi.org/10.1017/S002081830003352X.
17. Jaeschke, Engere Union; Christiansen et al. Maastricht Treaty