Robert Gerwarth, a professor of modern history at University College Dublin and Director of its Centre for War Studies, examines the legacy of World War I in his new book, The Vanquished: Why the First World War Failed to End. He argues that it was not the fighting on the Western Front that proved so ruinous to Europe, but the devastating aftermath, as countries on both sides of the conflict experienced revolutions, pogroms, mass expulsions and the emergence of extreme ideologies such as fascism.