This book addresses one of the least understood issues in modern international history: how, between 1930 and 1945, Britain lost its global preeminence to the United States. The crucial years are 1930 to 1940, for which until now no comprehensive examination of Anglo-American relations exists. Transition of Power analyzes these relations in the pivotal decade, with an epilogue that deals with the Second World War after 1941. Britain and the United States, and their intertwined fates, were fundamental to the course of international history in these years.