Don't Mention the War! Second World War Remembrance and Support for European Cooperation

The notion that through increased state cooperation and dependency, national divisions can be overcome and peace can be secured, is at the core of European integration. Political elites often refer to the devastations of the Second World War (WWII) as a way to convey the added value of European cooperation today. Do references to the devastations of WWII enhance public support for European cooperation today? By presenting evidence from survey experiments conducted in the six largest member states (France, Germany, Italy, Poland, Spain and the Great Britain) in July 2017, this study suggest that they do, albeit only when it comes to financial assistance for other member states in dire economic need. References to the devastations of WWII do not make respondents more willing to support free movement of people or the establishment of a European army. These findings suggest that reminding people of the devastations of WWII triggers a largely transactional response among the public: a willingness to provide financial support, but nothing more. This evidence suggests that securing public support for free movement of people or European security cooperation through historical rhetoric might be difficult to achieve.


Introduction
On the 12 October 2012, the EU received an important international recognition, the Nobel peace prize, for its achievements. The committee awarded the Nobel Peace Prize for the EU's contribution to 'the advancement of peace and reconciliation, democracy and human rights in Europe' for over six decades. 1 Europe's founding fathers, such as Jean Monnet or Robert Schuman, continuously stressed the importance of European cooperation and political dependencies in overcoming war and animosity. Unity on the European continent was seen as a crucial element of maintaining peace. The goal of overcoming national animosities through cooperation is also at the heart of early writings of federalist thinkers, like Altiero Spinelli who wrote: The dividing line between progressive and reactionary parties no longer follows the formal line of greater or lesser democracy, or of more or less socialism to be instituted; rather the division falls along the line, very new and substantial, that separates the party members into two groups. The first is made up of those who conceive the essential purpose and goal of struggle as the ancient one, that is, the conquest of national political powerand who, although involuntarily, play into the hands of reactionary forces, letting the incandescent lava of popular passions set in the old moulds, and thus allowing old absurdities to arise once again. The second are those who see the creation of a solid international State as the main purpose; they will direct popular forces toward this goal, and, having won national power, will use it first and foremost as an instrument for achieving international unit (Spinelli and Rossi, 1942, p. 8).
Historians view the legacy of the Second World War (WWII) as a key factor in shaping adherence to the European project and a collective understanding of what it means to be European (Dinan, 2004(Dinan, , 2006. Political elites often refer to the devastations of WWII in order to convey the added value of European cooperation and remind the people of a shared past. Think, for example, of former German Chancellor Helmut Kohl when he said that 'the most important rule of the new Europe is: there must never again be violence in Europe '. 2 When it comes to public opinion, a growing body of work demonstrates the importance of collective identities for understanding who supports or opposes transnational policymaking in Europe (for an overview see Hobolt and De Vries, 2016). Over the past decade or so, students of European integration have highlighted a variety of aspects. Some stress the importance of symbols, such a flags or money (Bruter, 2005;McNamara, 2015), others highlight crises and political mobilization (Börzel and Risse, 2020), again others point to the role of transnational interactions and contact (Favell, 2008;Kuhn, 2015), while others focus on the exclusive or inclusive nature of territorial identities Marks, 2005, 2009). Yet the role that narratives about a shared historical past play in the development of identities or people's perceptions of the European project has received much less attention in the literature (for notable exceptions see Diez Medrano, 2003). This is perhaps not entirely surprising, given the fact that the vast majority of studies of European public opinion to date are quantitative in nature and make use of existing surveys. The reliance on secondary survey data can be a serious setback for research, as existing datasets are often limited in their scope, especially when it comes to the measurement of identity or historical narratives (see also Checkel and Katzenstein, 2009).
While the lack of scholarly attention is thus understandable, it is nonetheless unfortunate. In the context of public opinion towards Europe and the role that the past plays, historical narratives can be perceived to be an integral part of identity formation (Diez Medrano, 2003;Risse, 2010). Benedict Anderson (1991) in his seminal book Imagined Communities, for example, stresses the importance of history and histography in shaping imagined communities. These imagined communities may frame people's identity in relation to transnational or foreign policy involving other countries as well as policies towards immigrants or other non-nationals. What is more, given the fact that the EU is largely a top-down elite driven project, European elites have made considerable efforts to foster European identity construction through symbols, such as the Euro or European flag, for example, as well as through collective memory construction (McNamara, 2015, Sierp, 2014; on top-down identity construction, also see Hofmann and Menard (2020) and McNamara and Musgrave, 2020). While this work is crucially important, less attention is paid to the role of historical narratives. Yet Risse (2010) reminds us that a collective identity, 3 like the European one, needs to juxtapose itself against a common other, and that in the case of the EU, this common other is often the past. Viewed in this light, historical narratives can be expected to be of crucial importance for understanding public opinion towards European integration.
While this contribution by no means claims to fill the gap in our understanding of how historical narratives structure public opinion, it aims to shed light on a specific aspect of this relationship. It examines how one specific historical narrative about the importance of the EU; namely, a narrative based on the devastations of WWII that has become very prominent in elite rhetoric can help us understand public opinion towards European integration today. Not only does this study present unique evidence from a survey experiment designed to understand how support for European cooperation changes after people were reminded of the devastations of WWII, it also presents a theoretical lens rooted in benchmarking theory, through which we can understand how a historical narrative may affect public opinion formation towards the European integration.
Specifically, this contribution suggests that the WWII devastations narrative provides an important benchmark against which a possible alternative to European cooperation can be judged. By rooting the theoretical approach in the benchmarking theory, this study moves beyond the current state of the art in EU public opinion research, in which identity is mostly juxtaposed with interest as alternative explanations of attitude formation (see also Kuhn and Nicoli, 2020). This study suggests that it may be more useful to explore how identity and interest explanations interact. A focus on historical benchmarks aims to do exactly that.
The empirical evidence presented here is based on the analysis of survey experiments conducted in the six largest member states (France, Germany, Italy, Poland, Spain and the UK) in July 2017. 4 In these experiments, one set of respondents was exposed to an experimental vignette describing the devastations of WWII before soliciting their views about European cooperation, while others were exposed after they had already answered survey questions about their views on European cooperation. Exposure to the experimental vignette prior to answering questions about European cooperation increases the support of respondents' for their country to cooperate within the EU today, yet only when it comes to financial assistance for other member states in dire economic need. There is no change when it comes to support for the free movement of people or the establishment of a European army. This evidence suggests that garnering public support for the free movement of people and European defence cooperation through historical rhetoric may not be easy to achieve.

Historical Narratives and Public Opinion Towards European Integration
In his influential book Framing Europe, Juan Diez Medrano (2003) reminds us that a variety of historical narratives about the European project exists. Different narratives have emerged about WWII over time, such as the defeat of Nazism or the start of the cold war, as well as across countries relating to defeat (most prominently in Germany) or victory (most prominently in the UK) in war. One grand European narrative about WWII that has emerged focuses on the devastations of this brutal conflict for the European continent. Indeed, the idea of 'never again' is at the heart of the European integration project that developed during and in aftermath of the war. At the core of European project is the idea that through increased economic and political cooperation, peace can be secured and sustained on the European continent as well as national divisions and animosities can be overcome. One of Europe's founding father, Jean Monnet, warned that without cooperation, war would remain the ultimate means to deal divergent national interests on the European continent (Fransen, 2001). Much more recently, the former Prime Minister of Luxembourg and Commission President Jean-Claude Juncker added that 'anyone who believes that the eternal question of war and peace in Europe is no longer there, risks being deeply mistaken.' 5 When political elites like Jean Monnet or Jean-Claude Juncker refer to a specific historical narrative based on the devastations of WWII, they intend to highlight the added value of European cooperation and the possible risks associated with a loss of cooperation. Essentially, they are providing the public with a historical benchmark against which the costs and benefits of integration can be evaluated. They pit the costs associated with a possible alternative state (devastations associated with war) against the benefits of the status quo of European cooperation (benefits of peace). This type of reasoning fits the benchmarking theory of public opinion towards Europe. This theory suggests that people's attitudes towards the EU ultimately boil down to a comparison of the status quo of their country's EU membership and their evaluations of a possible alternative state (De Vries, 2018).
Benchmarking involves counterfactual reasoning: how well would my country fare or have fared outside the EU? Counterfactuals are unknown so people rely on benchmarks to compensate for these informational shortfalls. The question then becomes how people benchmark the alternative state. Studies have demonstrated that people benchmark the alternative state by extrapolating from current national conditions, specifically national economic performance and quality of government (De Vries, 2018). Similarly, the alternative state can be benchmarked based on previous precedents of other countries leaving, especially the UK's experiences with Brexit (De Vries, 2017Vries, , 2018. 6 Support for European integration and cooperation is higher when people think that they or their country would be worse off under the alternative state scenario. The extent to which people support the status quo of membership thus crucially depends on their beliefs about how well their country would do if the alternative state materialized, with the information they use to form these beliefs. The idea of benchmarking builds on existing work highlighting the importance of national context in public opinion formation towards European integration. This work suggests that national performance evaluations are crucial for understanding people's support for integration. Sánchez-Cuenca (2000), for example, argues that citizens who are mainly dissatisfied with performance at the national level because of corruption are more willing to transfer sovereignty to the EU level. Moreover, Rohrschneider (2002) shows that citizens who perceive their national democratic institutions to be working well show lower levels of EU support because they view the EU to be democratically deficient. Furthermore, Rohrschneider and Loveless (2010) show that this relationship is conditional upon the overall level of economic prosperity in a country. Citizens in the less affluent nations evaluate the EU mainly on the basis of its economic performance, while in the more affluent nations the public relies mostly on political criteria, such as the functioning of their national democracies. What is different in the benchmark approach is that rather than viewing national context as influencing public opinion in a one-directional way, flowing from national to European evaluations, it suggests that the flow can be two-directional, or that events in one national context can impact on people's comparisons of the benefits of the status quo of membership as well as the alternative state in another national context (see also, for example, the benchmark approach in economic voting by Kayser and Peress [2012]).
While the alternative state is often understood as a hypothetical one in which one's country is not a member of the EU, it seems reasonable to think that a comparison of benefits and costs associated with the status quo and an alternative state could also be made on the basis of a historical benchmark. Historical benchmarks feature prominently in work of psychologists and sociologists on nostalgia, for example. While psychologists view feelings of nostalgia, commonly quite casually defined as a feeling that the past used to be better, primarily with reference to personal experiences, such as a birth, degree or other personal milestones (Batcho, 1995;Sedikides et al., 2008), sociologists define it in a much broader sense and relate it to more general views about the state of the world (Davis, 1979;Duyvendak, 2011). Notwithstanding these differences, both approaches emphasize that nostalgia develops in comparison with a benchmark in the past.
This suggests that to understand public opinion towards Europe as a comparison between the costs and benefits of the status quo of membership and those associated with an alternative state, a historical narrative, reminding people of the devastations of WWII, can have the potential to be important. Providing people with such a narrative presents a negative historical benchmark of how an alternative to European integration might look like. It can thus be expected to feed into the calculations of the costs and benefits of the status quo versus an alternative historical state, which is the essence of benchmarking theory. The EU developed as a peace project against the backdrop of the devastations of WWII (Dinan, 2004). Reminding people of these devastations and this historical past should increase support for their country's cooperation with other member states in the EU. This is because providing people with a negative historical benchmark highlights the risks and possible costs associated with the alternative state. Reducing the attractiveness of the alternative state by reminding people of the devastations of WWII serves as a reminder of the benefits associated with peaceful cooperation. This comparison should increase support for European cooperation today.

Historical Benchmarks and Support for European Cooperation
As noted in the previous section, the benchmarking theory leads one to expect that reminding people of the devastations of WWII should increase support for European cooperation. At this point, it seems important to reflect more on what public support for European cooperation might entail. Clearly, different forms of European cooperation exist. While some of these areas of European cooperation are largely uncontroversial in the eyes of the public, given the clear added value of cross-border cooperation, think of pollution or the protection of privacy for example other areas may be much more controversial. Some authors suggest that this may especially be the case when they involve core state powers (see Kuhn and Nicoli, 2020).
This raises the question of how to define core state powers. Bremer et al. (2020) describe two approaches: one based on policy area and another based on power resources. In the policy-based approach, policy areas are perceived to differ on the basis of how important they are for defining a state as a sovereign entity. Examples of these include the political notion of high politics (Hoffmann, 1966) or the legal notion of reserved powers (Weiler, 1991). In the resource-based approach, core state powers refer to the resources deriving from the monopoly of legitimate coercion and taxation of a state: coercive capacity (military, police, border patrol), fiscal capacity (money, taxes, debt) and the administrative capacity needed to manage coercive and fiscal capacity and to implement and enforce public laws and policies (see Tilly, 1990;Weber, 1978). While these definitions differ, they also overlap. In both approaches the core areas of sovereign government usually involve the mobilization and direction of coercive, fiscal or administrative capacities: think of defence policy, budgetary policy, social security policy or border control as examples.
When we keep these commonalities in mind and think about how they overlap with areas in which further cooperation which are currently salient in European and domestic political discourse, three areas stand out: (1) financial assistance for economically struggling member states, (2) the free movement of people, and (3) enhanced defence and security cooperation in Europe. These areas of European cooperation involve core state powers, as they touch on issues of territory and border, taxation and spending as well as coercive capacity. In addition, scholarly work suggests that they are among the most important areas of European cooperation in the eyes of voters (see De Vries, 2018;Kuhn et al., 2017;Vasilopoulou and Talving, 2018). The empirical analysis, therefore, examines how providing people with a negative historical benchmark based on the devastations of WWII narrative affects public support for more European cooperation in financial assistance, the free movement of people and European defence cooperation, respectively.

Experimental Design
To test whether providing people with a negative historical benchmark by reminding them of the devastations of WWII increases support for European cooperation, this study presents the evidence from a survey experiment. The survey experiment was embedded in the July 2017 survey wave of eupinions, a politically independent platform that collects data on European public opinion. 7 The survey is conducted via a mobile phone sample and is representative with regard to age, 8 gender, education and region. A survey 7 The data were collected by Dalia Research and funded by the Bertelsmann Foundation. The embedding of the experiment in an existing survey constrained the number of countries that could be included, see also footnote 5. 8 Note that the survey includes respondents aged between 18 and 65 years old. The fact that the oldest cohorts are not included most likely leads to a conservative test of the hypotheses, given that none of the respondents had lived through the war. experiment was embedded in surveys conducted in the six largest EU member states in term of population, France, Germany, Great Britain, 9 Italy, Poland and Spain. Overall, 7521 respondents participated in the survey experiment, 1 262 in France, 1 644 in Germany, 1 270 in Great Britain, 1 277 in Italy, 1 060 in Poland and 1 008 in Spain.
The experiment was designed to activate people's memory of the devastations of the WWII through an experimental vignette. These devastations relate to the costs of war and thus include a variety of losses, including losing loved ones, economic livelihoods, or a home. The wording of the vignette was as follows: The Second World War was a global war that lasted from 1939 to 1945. It was one of the deadliest military conflicts in human history. Over 60 million people were killed including innocent children. The war had devastating effects on the European continent. Many people lost everything, their economic livelihoods, their homes or even loved ones.
The order in which respondents received this vignette was randomized. One group of respondents, the treatment group, received the experimental vignette prior to answering a set of questions eliciting their views about political cooperation in Europe, while another group of respondents, the control group, received the vignette after answering these questions.
To make sure that the respondents understood the vignette, both the treatment and control group were given the following question after the vignette: How many people lost their lives in the Second World War? This served as a manipulation check. Respondents were provided with two possible answer categories, one that was false, 6 million people, and one which was correct, 60 million people. Overall, 83 per cent of respondents answered the follow-up question correctly, which suggests that most of them had read and understood the vignette. Also, there were no differences in the degree of correct answers based on the placement of the vignette, before or after the questions asking about people's views about European cooperation. The empirical results presented in the next section are based on analyses including all respondents. This constitutes the most conservative test of the effect of the vignette. Figure S1 in the Supporting Information also displays the results when replicating the analysis only with the respondents who answered the manipulation check correctly. The results remained the same.
After the vignette and manipulation check, the respondents in the treatment group were presented with three questions soliciting their views about future cooperation in Europe. The respondents in the control group received these questions before being exposed to the vignette, while the treatment group was exposed to vignette first and then answered the questions. Specifically, respondents were asked the following three questions: 1. To what extent do you think that [your country] should provide financial aid to another EU Member State facing severe economic problems? Answers were set out along a 10point scale ranging from 1 'My country should not give financial aid' to 10 'My country should give financial aid'.
2. To what extent do you think that [your country] should try to limit the rights of EU citizens to work and live here? Answers were set out along a 10-point scale ranging from 1 'My country should not allow them to work and live here' to 10: 'My country should allow them to work and live here'.

To what extent do you think [your country] should help to establish a European army?
Answers were set out along a 10-point scale ranging from 1 'My country should not help' to 10: 'My country should help'.
The wording of the questions on free movement is not ideal. This is because the labels of the end-points of the scale refer to stopping free movement rather than to extending free movement. The question might thus tap into support for free movement more generally. Therefore, it is referred to as such. The order of the three questions was randomized to rule out any ordering effects. In order to examine whether reminding people of the devastations of the WWII increases support for their cooperation in Europe, we compared the answers of the respondents who received the vignette before the questions with those who received the vignette after the questions.
The vignette was designed to activate people's memory of the devastations of the WWII, and not to trigger sentiment towards perpetrators. In order to rule out the possibility that the vignette increased anti-German sentiment, two additional survey questions soliciting people's views about European cooperation were included after the questions about European cooperation. Again, the treatment group answered these questions after being exposed to the vignette, while the control group answered these questions before. The two questions were the following: 1. How much do you approve of German Chancellor Angela Merkel? Respondents could choose from the following answers: (1) completely approve, (2) somewhat approve, (3) somewhat disapprove, (4) completely disapprove. 2. Germany is often seen as taking a leadership role in the European Union. Do you think this is …? Respondents could choose from the following answer categories: (1) very good, (2) good, (3) bad, (4) very bad.
When it comes to respondents' answers to the first question, the average response of the treatment group was 2.57; closest to 'somewhat disapprove', and that of the control group was 2.59, also closest to 'somewhat disapprove'. This difference is small (À0.02) and not statistically significant (p = 0.55). When it comes to the second question, the average response of the treatment group was 2.47; closest to 'bad', and that of the control group was 2.49, also closest to 'bad'. This difference is again very small (À0.02), and failed to reach conventional levels of statistical significance (p = 0.20). Finally, in order to make sure that possible differences in support for European cooperation between the treatment and control groups were not driven by other characteristics in which the two groups might differ, balance tests were conducted (Table 1).
The question wordings for each variable are shown in Table 2. Table 1 shows that no significant differences between the treatment and control groups exist when it comes to background variables. This finding increases our confidence in the experimental results.

Empirical Results
Before presenting the results from the survey experiment, Figures 1a and 1b provide a sense of the average support for assisting struggling member states financially, for free movement and for aiding the establishment of a European army. While Figure 1a shows the mean level of support for European cooperation in the three areas averaged out across the six countries, Figure 1b shows the mean level of support in each of the six countries separately. Figure 1b shows that respondents are close to the mid-point of the scale when it comes to the three areas of European cooperation (average support is slightly higher than 5 on the three 10-point scales). The differences between the three areas of cooperation are very In which town do you live? (urban = 0, rural = 1) Education Which of the following best describes your formal education? (lowest = 1, highest = 5) Gender Do you identify as a man, women or neither (male = 0, female = 1) Left-right ideology If you had to choose one of the below, which option best describes your political views on a left-right scale? (extreme left = 1, extreme right = 6) Evaluation economic situation How has your personal economic situation changed in the last two years? (1 = got a lot worse, 5 = got a lot better); Class Do you see yourself as …? (lower class = 1, lower middle class = 2, lower upper class = 3, upper class = 4) Support for remaining in EU Imagine there is a referendum and you could decide whether your country stays as a member of the European Union. How would you vote? (don't know = 1, leave = 2, remain = 3) small. Figure 1b suggests that there are some differences across the six countries under investigation, albeit not large ones. In France, for example, respondents were most positive about their country providing support for the establishment of a European army, while in Great Britain this proposed area of cooperation found least support. Yet, these differences are very small and suggest that average levels of public support for European cooperation do not starkly differ across the six largest member states.
What happens if respondents are provided with a historical benchmark reminding them of the devastations of the WWII; a time when Europe was hugely polarized and states were at war with one another. Figure 2 displays the results of a regression analysis in which the respondents from all six countries were pooled to estimate the change in support for European cooperation based on being exposed to the WWII vignette. The analysis included country fixed effects to deal with potential heterogeneity across countries. The results suggest that reminding respondents of the devastations of WWII increased their support for providing financial assistance to a struggling member state. At the same time, there is no effect on support for free movement or the establishment of a European army. Support for financial assistance is about a quarter of a point higher for those who were exposed to the WWII vignette than for those who were not. Given that support for financial assistance was measured on a 10-point scale, this would be equivalent to a 2.5 per cent increase in support. In the case of financial assistance, the finding is in line with the benchmarking theory of public opinion towards the EU that suggests, when that providing people with an alternative state that is negative, support for the European cooperation should increase. Yet, this result is restricted to financial assistance only ( Figure 2). Do these effects vary across the six largest member states? Figure 3 displays this information. In the case of free movement and a European army the results are very similar across the six largest members states: being exposed to the vignette about the devastations of WWII has little to no effect on support for European cooperation. Yet, when it comes to financial assistance the results show that being exposed to the vignette increases support for financial assistance in the largest member states, with the exception of Italy and Poland. Reminding Italian and Polish respondents of the devastations of the WWII had no effect on their support for providing financial assistance to economically struggling member states. Why exposure to the vignette did not trigger the same response in Italian and Polish respondents is unknown at this point. Further research is needed to address country difference in depth. 10 The last step in the empirical analysis examined potential heterogeneous effects based on ideology. 11 Previous work has suggested that people on the right of the political spectrum are less likely compared to those on the left of the political spectrum to support financial aid to other member states or the extension of rights to EU citizens (Kuhn et al. 2017;Vasilopoulou and Talving, 2018). In addition, historically the left has been quite wary of the establishment of a European army (Hofmann, 2013). For these reasons, one could expect differences based on respondent's ideological self-placement. In the survey, respondents were asked in the pre-treatment section of the survey how they identify themselves politically in left or right terms. The answer categories differ from (1) very left wing to (6) very right wing. While most of the respondents self-identified as centre-left or centre right, a considerable proportion; namely, 10 per cent, placed themselves either on the very left or very right of the political spectrum. Figure 4 shows the effect of being exposed to the WWII vignette by left-right ideological self-placement based on a regression that includes an interaction between the vignette and ideology.
The results of the analysis show that while left-leaning versus right-leaning respondents do not really differ in how they feel about free movement after being exposed to 11 I also examined possible age effects, but none of the interactions with age proved to be statistically significant at conventional levels. the vignette, they do when it comes to views on financial assistance and aid to a European army. In the latter case we see that only left-wing respondents differ based on their exposure to the vignette. Specifically, when left-wing respondents are reminded of the devastations of WWII they are more likely to support their country providing financial assistance to a member state in need. There seems to be no difference for respondents who self-identify as centrist or right wing. When it comes to potential aid to a European army, the results suggest that left-wing respondents respond more to the vignette compared to right-wing respondents. Respondents who identify as left-wing exposed to the vignette are more likely to support their country providing aid to a European army than when they are not exposed. Interestingly, this suggests that respondents who self-identify on the left respond slightly in a stronger way to the historical benchmark based on the devastations of WWII than right-wing respondents do.

Conclusion
Does reminding people of the devastations of WWII enhance support for European cooperation today? Based on the benchmarking theory of public opinion towards European integration, one would expect that it would. The benchmarking theory suggests that people's evaluations of their country's membership in the EU is conditional upon their evaluations of a possible alternative state, that of their country being outside the EU. Because the alternative state is fundamentally based on a counterfactual, people need to rely on benchmarks. This contribution has examined whether providing people with a negative historical benchmark namely the devastations of WWII, increases their support for European cooperation.
By presenting evidence from novel survey experiments that were conducted in the six largest member states in July 2017, this contribution has shown that exposure to a negative historical benchmark, based on reminding people of the devastations of WWII, increases support for their country's cooperation in Europe, as expected, but only when it comes to financial assistance for other member states in dire economic need. It does not make respondents more supportive of the free movement of people or the establishment of a European army. By and large, these findings suggest that WWII remembrance triggers a largely transactional response among the public. While providing people with a historical benchmark increases their support for financial assistance to other member states in economic need, it does not increase their willingness to extend the rights of European migrants or to aid in the defence of other member states. That said, the analysis also suggests that differences based on individual characteristics exist. Those who self-identify as leftwing respond slightly more strongly to the historical benchmark based on the devastations of WWII than right-wing respondents do.
Overall, this evidence suggests that securing public support for European reform proposals aimed at deepening the free movement of people and security cooperation through historical rhetoric may be difficult to achieve. Why exposure to the vignette triggered a response to financial aid but not to cooperation in other policy areas is an important area for future research. I have suggested that this may be due to the largely transactional nature of public opinion (De Vries, 2018), but the extent to which this is the case will be an important avenue for further investigation. The evidence provided here also raises interesting questions about how perceptions of a shared European history may help us to understand the contours of public opinion towards European integration and the conditions under which they do. Coming to grips with the way people perceive Europe's history in future work may also allow us to understand what constitutes European identity, how it affects support for and opposition to European integration, and how political rhetoric highlighting these historical experiences may matter.

Supporting Information
Additional supporting information may be found online in the Supporting Information section at the end of the article.