The Third Republic survived World War I (1914–18) but quickly collapsed in the face of a Nazi German invasion in 1940. Marshal Henri Philippe Petain, the republic's last prime minister, agreed to an armistice that allowed German forces to occupy and administer much of the country, including Paris. Meanwhile, the constitution was suspended and Petain became the leader of a Fascist puppet regime based in Vichy, in central France. In 1942, the Germans occupied the whole country. But for the rest of World War II, the Vichy government cooperated fully with the Germans, hunting down and executing resistance fighters, contributing French labor and resources to the German war effort, and helping to round up tens of thousands of Jews for deportation and mass murder.
During the war, many French took part in the resistance movement against German occupation, engaging in spying, sabotage, and guerrilla fighting. General Charles de Gaulle escaped to London and helped establish a Free French army and government in exile. But large numbers of businessmen, civil service workers, and police collaborated with the occupiers. The Vichy regime came to an end after the successful Allied invasion of France in June 1944. A provisional government headed by de Gaulle gave way in 1946 to the Fourth Republic, which was similar in constitutional structure to the Third. The Communist Party, which had been active in the wartime resistance, gained prominence immediately after the war, raising fears that France would align itself with the Soviet Union. However, American aid through the Marshall Plan and France's other political parties helped to rebuild the country on a democratic footing. France later emerged as one of Europe's strongest economies and a leading force in the creation of the European Union (EU).