The year 1945 was a breakthrough for Europe’s Communists. Paradoxically, the Soviet role in liberating the continent from German fascism meant that the Communists were lifted to power in Eastern countries, where both capitalism and the workers’ movement were mostly relatively weak. There were mass Communist Parties in the West, too. But Cold War conditions kept them from high office, including thanks to considerable US secret service activity — and in Greece, a bloody civil war.

The basis for communism as a Western European mass movement was its role in the fight against fascism and occupation. This was particularly true of France and Italy. In 1945, a radical Labour government came to power in Great Britain, supported by mass-membership trade unions, and the Social Democrats and Communists each grew rapidly across Allied-occupied postwar Germany. But it was especially the French Communist Party (PCF) — “the party of the 75,000 executed” — and the Italian Communist Party (PCI) that matured into huge mass organizations.

France’s PCF grew from thirty thousand members before the Popular Front policy to half a million by the end of 1945. It immediately became the strongest party in parliament with 26.2 percent of the vote and 159 seats in the National Assembly. One year later, it reached 28.3 percent and 182 MPs. In Italy, Communist Party membership soared from fifteen thousand to 1.7 million within a year. It soon became one of the capitalist world’s largest Communist parties, surpassed only by the Indonesian party, which peaked at three million members before the anti-Communist genocide of 1965.