Altiero Spinelli (1907–1986) was an Italian politician and an influential advocate of a federal, supranational Europe, a central figure in the intellectual and institutional history of European integration, whose work helped shape later developments in European governance. Imprisoned and confined by Mussolini’s fascist regime from 1927 to 1943, he developed a vision of European unity intended to overcome nationalism and prevent future wars, advancing this agenda through the European Federalist Movement and as member of the European Parliament.

Born in Rome to a socialist family, Spinelli joined the Italian Communist Party as a teenager, leading to his arrest in 1927 by the Fascist regime and sentenced to long imprisonment and internal exile. His decade in prison and subsequent confinement on the island of Ventotene, led him to undertake further studies, distancing himself from orthodox communism and concluding that European nationalism—not merely class struggle—was the structural cause of recurring wars.

In exile, Spinelli co-authored the Ventotene Manifesto (initially titled “For a Free and United Europe”), one of the earliest systematic arguments for a European federation, proposing a constitutional and supranational structure capable of transcending the sovereignty of nation-states and ensuring lasting peace. It was this Manifesto which became a foundational text of post-war European federalism.

Upon his release in 1943, Spinelli founded the Movimento Federalista Europeo and dedicated himself to promoting European political integration, working with leading European statesmen and later serving as a member of the European Commission. In 1979 he was elected to the first directly elected European Parliament and continued to advocate for even deeper federal integration.

In 1980 Spinelli founded the “Crocodile Club” within the European Parliament, and this initiative with other like-minded members, culminated in the Parliament’s adoption, in February 1984, of the Draft Treaty Establishing the European Union, often referred to as the “Spinelli Plan” which significantly influenced subsequent treaty reforms and strengthened the role of the European Parliament in the integration process. Appropriately, the main building of the European Parliament in Brussels bears his name, in recognition of his contribution.