Natural and Necessary Unions is a history for our time. It shows that the choice between "union and independence" that shapes current debates about the future of the United Kingdom in the age of Brexit is a false one. Against the countervailing currents of hegemony and fragmentation that range across centuries - from the economic dominance of southern England and the burdens of social democracy to the rise of separatist nationalisms and European integration - unionists struggled to make a union-state that would protect the independence of its citizens and communities from these wider forces. Natural and Necessary Unions tells the story of how the quest for autonomy shaped the history of three communities: Scotland, Ireland, and Northumbria. It charts the different choices these societies made about their relationships within the British Isles and in wider international society, crystallizing in the choice that must be made again between the British and European unions. From these wildly differing experiences, Scotland's devolution emerges as an enviable middle-ground, compared to Ireland's satellite status and the hyper-centralism of England. Drawing on a wealth of evidence from polls to poetry, and a cast of characters ranging from Edmund Burke and Gordon Brown to Gerry Adams and Alex Salmond, Natural and Necessary Unions points the way to a new unionist politics for the twenty-first century.