The introduction establishes the book’s central argument: the German nation-state was shaped not only by domestic dynamics but also by its colonial empire. Rather than treating empire and the nation-state as incompatible forms of political organisation, the chapter situates them within a shared global constellation and underscores their historical interdependence. Moving beyond debates that focus exclusively on colonial legacies that mirror colonial structures – such as racism and global inequality – it argues that we must also attend to structural effects of empire that assumed different forms, thereby concealing their colonial origins. The European nation-state exemplifies this apparent paradox: historically shaped by overseas empire building yet appearing as its polar opposite. Against this backdrop, the chapter critically engages with scholarship ranging from Hannah Arendt’s reflections on imperialism to more recent debates on global entanglements, while advancing a mechanism-based approach. Its key conceptual innovation is to introduce challenge and response as a mechanism through which crises in the colonies prompted reforms in the metropole that contributed to the consolidation of the nation-state.