This book tells the history of the 'federal union', a concept that may be traced from the early Renaissance to the establishment of the European Coal and Steel Community (1951), the predecessor of today's European Union. It is a story of three federal canons: of greater and lesser thinkers, of utopian peace plans, and of practical experiences with federal unions. Together they shaped the concepts that created the ECSC. This book unlocks the past of the EU, a union that always thought it didn't have a past, but was, on the contrary, 'sui generis', without examples or predecessors. Although there was nothing inevitable about the founding of the EU, A More Perfect Union shows that it was plausible and perhaps even predictable that such a union would be formed at some point, and that the aftermath of the Second World War was exactly the kind of founding moment about which federal theorists in previous centuries had speculated.