When the Cold War ended between 1989 and 1991, statesmen and scholars reached back to the period after World War I when the victors devised minority treaties for the new and expanded states of Eastern Europe. This book is the first study of the entire period between 1878 and 1938, when the great powers established a system of external supervision to reduce the threats in Europe’s most volatile regions of irredentism, persecution, and uncontrolled waves of westward migration. It is a study of the strengths and weaknesses of an early state of international human rights diplomacy as practised by rival and often-uninformed Western political leaders, by ardent but divided Jewish advocates, and also by aggressive state minority champions, in the tumultuous age of nationalism and imperialism, bolshevism and fascism between Bismarck and Hitler.