"In 1900, radicals of Left and Right regarded the world order as rigged and unbalanced; favouring the dominant imperial democracy over all others; favouring sea over land; parliaments over the interests of classes and nations; reasoned debate over activist élan; capitalist self-interest over collective aspirations."

From Mussolini to Lenin, from Sorel toc Hitler, nothing about the notorious revolutionaries of Left and Right who would transform Europe in the first half of the twentieth century stayed fixed and unchanging. Their ideas changed as the context changed and then so duly did their policies and their political strategies. But it was their ideas rather than economic or social developments that drove the greatest political transformations the world had ever seen. Ideas change history, is Valdez's core belief. And his revisionist new history of the thinking powering the parallel movements of fascism, communism and Nazism shows how they intertwined to drive change, how their thinking converged as much as they clashed on the streets.

As the imperial democracies consolidated their power, their challengers from Left and Right came to the view that only War could breed the revolution they desired, the ethnonationalist on one side, the proletarian on the other.

'Valdez is coming! This remarkable, innovative book, written by an expert in the field, will show how revolutionaries of the right and left held the democracies in a vice grip.'

-- Brendan Simms, Professor of the History of International Relations, University of Cambridge, and author of Hitler and Europe: the Struggle for Supremacy

'This book offers a bold and gripping interpretation of the remaking of Europe’s place in the world. It emphasises the fundamental importance of ideas, explaining how radical thinkers came to determine European and global politics in the first decades of the 20th century through the power of their ideological visions. '

-- William Mulligan, Professor of History, UCD, author of The Great War for Peace

'An original take on the relationship between war and revolutionary ideas in Europe in the twentieth century.'

-- Dominic Lieven, Visiting Professor of International History, LSE, and author of Towards the Flame

War of Ideas: A History of Revolutionary Europe 1900-1945