Based on new archival research, this is the first comprehensive study of the failure of international co-operation to combat the Great Depression. The book explores the impact of protectionism, reparations and war debts, as well as the more well known disagreements on monetary issues which, together, helped to prolong the most profound economic depression of the twentieth century. The economic and diplomatic lessons drawn from this period by the major powers – particularly German intelligence as to the deep divisions in Anglo-American economic relations – also provide an important contribution to understanding the origins of the Second World War and the diplomatic and economic order created in its aftermath.