Remembering Peace in a Time of War: Why International Law Matters More Than Ever | Brokering Peace

For a Free and United Europe Building Integration, Ensuring Peace

“In Peace, Sons bury their Fathers.
In War, Fathers bury their Sons.”
Herodotus

The European Union’s Birthday

“Europe Day” commemorates the Schuman declaration of 9 May 1950, which initiated the European integration process with peacebuilding as the cornerstone. In the aftermath of WWII, ensuring peace in Europe was an existential objective. Europe had long been a continent of constant wars, with states fighting to conquer, dominate or shift the balance of power. After two devastating world wars, it became clear that the traditional Westphalian system based on absolute state sovereignty had failed, as it could not contain rising nationalism or secession movements in Europe. Profoundly divided and dramatically flattened, European states faced the existential threat of losing their independence and the ability to determine their own future.

Therefore, in his declaration, Schuman affirmed: ‘Europe will not be made all at once, or according to a single plan. It will be built through concrete achievements, which first create a de facto solidarity.’ This solidarity was necessary for peace, which required ‘creative efforts proportionate to the dangers which threaten it’. The founding fathers of the European Coal and Steel Community (ECSC) in 1951 agreed to share economic resources to prevent future conflicts: ‘[t]he pooling of coal and steel production … will change the destinies of those regions which have long been devoted to the manufacture of munitions of war, of which they have been the most constant victims’.

The Seeds of the European Idea

If nationalistic resurgence contributed to WWI, the aftermath saw the collapse of empires and the creation of new States. Still, peace efforts like the Treaty of Versailles and the League of Nations failed also because they did not challenge the core principle of absolute sovereignty. Hence, the inter-war period revived discussions on European integration as an alternative to destructive interstate rivalry. To renounce war as an instrument of national policy, the Kellogg-Briand Pact was signed by 15 States, which engaged themselves in not using war to resolve ‘disputes or conflicts of whatever nature or of whatever origin they may be, which may arise among them’. Although it lacked enforcement and did not mention trade’s role in peace, it signalled a decline in inter-state war as a structuring principle of international relations. These peacebuilding ideas laid the groundwork for post-WWII European integration.

During WWII, visions of a free and united Europe and the ideals of peace and stability, solidarity and integration among European peoples continued to be cultivated and promoted. This was the case of Altiero Spinelli and Ernesto Rossi, who were exiled to Ventotene during WWII. In 1941, they wrote a manifesto advocating for a federal Europe, which circulated widely among the European people. To some extent, their ideas echoed past ideas or models on achieving peace in Europe, which intrigued thinkers since the Middle Ages. In this sense, it is worth mentioning the projet pour la paix perpétuelle en Europe, where Charles-Irénée Castel de Saint-Pierre not only emphasised the impossibility of securing peace through a hegemonic power but, above all, showed how ‘a balance of power between the nations’, considered the most effective method for maintaining peace from the Treaty of Westphalia onwards, could not work. On the contrary, this method paradoxically had the opposite effect, leading to conflicts between nations. Hence, by following a legal approach and a model of a federation of states, he proposed creating common jurisdictions to establish a “European Union”. Furthermore, in projet de paix perpetuelle, Immanuel Kant, pursuing the aim of universalising these ideas and recalling Montesquieu’s concept of “doux commerce”, suggested that ‘a commercial spirit of international trade’ and a federation of independent republics would have ensured perpetual peace.

The Internal Market: A Key Factor in EU Integration

The Ventotene Manifesto laid the ideological foundation for a united, peaceful, and prosperous Europe, which saw its first flashes of light with the Schuman Plan and the creation of the ECSC. It aimed to ‘merge the economic interests between the sixth founders, to help raise the living standards and be the first step towards a more united Europe’. The ECSC differentiated itself from the neo-constituted Council of Europe and the United Nations for breaking the principle of absolute sovereignty: states limited their sovereignty over crucial raw materials for war in favour of a higher authority (today, the European Commission) with “supranational” powers. Hence, the European integration process started as an attempt to overcome the constraints of the Westphalian system.

The failure of the European Defence and Political Communities in 1954 pragmatically shifted the focus toward economic integration. The 1957 Treaties of Rome established the European Atomic Energy Community (Euratom) and the European Economic Community (EEC), which evolved into the European Union (EU) today. Committed to ‘an ever-closer Union amongst the people of Europe,’ the EEC prioritised creating a “common” or “single” market for enjoying four freedoms based on the free movement of goods, services, people, and capital. It also established a customs union, a common external tariff, and shared policies on competition, state aid, and agriculture.

The single market goes beyond facilitating trade between the Member States. It aims to integrate national markets into a larger, unified market, thereby eliminating structural differences and promoting uniformity. While this brings economic benefits such as economies of scale, its ultimate goal was considered an essential step towards social and political integration.

The Building of the Internal Market

The EU Treaties employ a dual strategy to create a unified internal market from diverse national markets:

Negative integration: The EU removes unjustified national trade barriers and prohibits obstacles to intra-EU trade. Over time, this has evolved from the “host state control” principle typical of the international market model, where states limited external sovereignty to open their external borders, to the “home state control” principle typical of the federal market model, based on mutual recognition. Once a product complies with its home country’s laws, it can move freely within the EU. This shift has led to a partial loss of sovereignty for host states over their domestic markets. The federal model is predominant today and examines whether national regulations impose restrictions on intra-EU trade rather than focusing solely on discrimination against imports. However, recent case law from the Court of Justice of the European Union (CJEU) has also applied a national model aimed at removing trade restrictions altogether through uniform EU standards. In that way, the EU internal market is wholly assimilated to a national market.
Positive integration: The EU adopts legislation to harmonise national rules and remove barriers to trade within the Union. The Treaties grant the EU the competence to legislate for the internal market, including harmonisation measures to ensure its smooth functioning.

Conclusion

War has shaped European history for centuries, and it has often been used to conquer or destroy one another. Additionally, Europe fell victim to the underlying concepts that had fuelled the Westphalian system it had created. The historical importance of the European integration process lies in challenging the latter, showing that it is anachronistic to govern an increasingly interconnected and globalised world.

The sentiment of a free and united Europe has gradually emerged from a climate of perpetual war. Based on shared values, States have limited their sovereignty in favour of the EU, which, within the limits of its competencies, can act to enforce and defend them. In this sense, the EU is a remarkable example of how a rule-based cooperation and integration system can replace war with peace: lasting peace can be achievable when states move beyond absolute sovereignty in favour of new collective governance models.

This experiment is unprecedented in modern history. In its first 75 years, the EU has transformed from a coal and steel community into a supranational entity with deep normative and decisional character, involved in nearly every aspect of modern life. Hence, the EU evolved beyond its international origins into a mature constitutional entity, a ‘federalism without federation’. The EU is mixed or compound and stands on a federal “middle ground” by combining international and national elements. Therefore, today, the EU’s nature best characterises it as a federation of States. The European integration process is ongoing and continues to expand rapidly. Still, the pooling of economic resources and building the internal market has been at its heart and crucial to ensuring long-lasting peace by making war ‘not merely unthinkable, but materially impossible in Europe’.