This article challenges the ontological assumptions of European Union (EU) theory that rest on the primacy of ‘states’. It also refutes the narrative of peace which is celebrated in scholarship and EU self-representation. It looks at early EU integration through the postcolonial lens and argues that both EU self-image and EU theory do not consider colonialism and empire and have silenced the violence committed outside Europe. Hence, they have produced a historically inaccurate and conceptually misleading account of early European integration. The post-colonial reading of the EU brings history back to the story of Europe to advance a revisionist account of theories of early European integration. The examination of arrangements laid out in Europe’s capitals – from Berlin in 1885 to Paris in 1919 to Rome in 1957 – reveals continuity of goals, motivations, and technologies of domination, rather than Europe’s ‘new beginnings’. The article demonstrates that the legal order established by the Treaty of Rome institutionalized the colonialism of EU members at the new supra-national level. It subordinated foreign people and economies to the interests of European capital, legitimized control of resources, camouflaged the old civilizing mission under a new guise of development, and reproduced and maintained the colonial racialized relationship of inequality and dependence. Ultimately, Rome infused the new European project with imperial, violent, hierarchical, and racial characteristics that remain unacknowledged by the EU theory.