With this important study of the early years of communism in France, Romain Ducoulombier has established himself as a historian of political culture and sociability of the first rank. His examination of the individual biographical trajectories and the coming together and fracturing of narrow groups of political activists that make up the fascinating and complex story of the far left in France after the First World War demonstrates his subtle grasp of the most minute and intimate of political relationships. His claim, indeed, is that the highly-charged historiographical significance of a moment like the 1920 Congress of the SFIO at Tours, when French socialism underwent a crude-edged, uncertain and ragged division, needs to be deconstructed. His patient and passionate exploration of the personal histories of the early communist militants in France, their emotional responses to war, and above all their struggle to identify clearly what ‘breaking with the past’ would entail for French socialism, is the answer he offers to many decades of historical debate about Tours and the birth of French communism. This makes his book highly detailed, intimate and complex. It will be especially satisfying for historians of political culture and society who have a sense that personal archives need to be read in several different registers at the same time; and that if the emotional force of a letter can be teased out it may well force a reconsideration of traditional views that had not neglected those very sources, but that had perhaps emphasized a more obvious reading.