In September 1939 Hitler invaded Poland, and France and Great Britain declared war. Both sides built up forces along to the Western Front, but for the next eight months neither side made a move: this was the "phony war". The German Blitzkrieg began in May 1940, and in six weeks of retreating the French lost 130,000 men. The Allied armies crumbled, but the British managed to rescue their own soldiers and about 100,000 French soldiers in the Dunkirk evacuation. France was defeated and had to sign an armistice with Nazi Germany on June 22, 1940. French soldiers became prisoners of war in Germany, were assigned to munitions factories as forced labor, and served as hostages. Nazi Germany occupied three fifths of France's territory (the Atlantic seaboard and most of France north of the Loire), leaving the rest to the new Vichy collaboration government established on July 10, 1940 under Henri Philippe Pétain. Its senior leaders acquiesced in the plunder of French resources, as well as the sending of French forced labor to Nazi Germany; in doing so, they claimed they hoped to preserve at least some small amount of French sovereignty. After an initial period of double-dealing and passive collaboration with the Nazis, the Vichy regime passed to active participation (largely the work of prime minister Pierre Laval). The Nazi German occupation proved costly; Nazi Germany appropriated a full one-half of France's public sector revenue. From 1942 to 1944 many French citizens were deported to death camps and Nazi concentration camps in Germany and Poland. On the other hand, those who refused defeat and collaboration with Nazi Germany, led by Charles de Gaulle, organized the Free French Forces in the UK. They coordinated resistance movements in occupied and Vichy France. By August 1944, 260,000 French regulars and 300,000 FFI were fighting in France. In June 1944 Allied forces, invaded and forced the Germans to retreat. France was liberated and the Petain regime ended. Paris was liberated on August 25. On September 10, de Gaulle installed his provisional government in Paris. France could now again participate as a partner in the war. In 1945, the French army numbered 1,300,000 men, 412,000 of whom were fighting in Germany and 40,000 in Italy. Post-war (1945–Present) History 1945-1999 France emerged from World War II to face a series of new problems. After a short period of provisional government initially led by General Charles de