Chapter 6 seeks to capture the tectonic changes the unprecedented cataclysm of the Great War engendered. It analyses both the catalytic and the transformative impact the war had on Europe, the United States and the wider world in every relevant sphere – international, domestic and transnational politics, economic order, finance as well as the realms of culture and worldviews. It then concentrates on mapping out how, at the core, the war fundamentally recast the transatlantic constellation, precipitating both the destruction of the pre-war European states-system and casting the United States in the role of the power that not only ultimately decided the outcome of the conflict but also seemed poised to dominate efforts to reorder Europe and the world in its aftermath.