During World War I, Paris was at the forefront of the war effort, having been spared a German invasion by the French and British victory at the First Battle of the Marne in 1914. In 1918–1919, it was the scene of Allied victory parades and peace negotiations. In the inter-war period, Paris was famed for its cultural and artistic communities and its nightlife. The city became a gathering place of artists from around the world, from exiled Russian composer Stravinsky and Spanish painters Picasso and Dalí to American writer Hemingway.
On 14 June 1940, five weeks after the start of the Battle of France, an undefended Paris fell to German occupation forces. The Germans marched past the Arc de Triomphe on the 140th anniversary of Napoleon‘s victory at the Battle of Marengo. German forces remained in Paris until the city was liberated in August 1944 after a resistance uprising, two and a half months after the Normandy invasion. Central Paris endured World War II practically unscathed, as there were no strategic targets for Allied bombers (train stations in central Paris are terminal stations; major factories were located in the suburbs). Also, German General von Choltitz did not destroy all Parisian monuments before any German retreat, as ordered by Adolf Hitler, who had visited the city in 1940.
In the post-war era, Paris experienced its largest development since the end of the Belle Époque in 1914. The suburbs began to expand considerably, with the construction of large social estates known as cités and the beginning of the business district La Défense. A comprehensive express subway network, the RER, was built to complement the Métro and serve the distant suburbs, while a network of freeways was developed in the suburbs, centred on the Périphérique expressway encircling the city.