The Liberation of Paris in World War II took place in late August 1944, marking the end of Operation Overlord. With the Allies rapidly advancing on Paris, the Paris Métro, Gendarmerie and Police went on strike on 15 August, followed by the postal workers the following day. They were joined by workers across the city when a general strike broke out on 18 August, the day on which all Parisians were ordered to mobilize. Barricades began to appear, with skirmishes between them and the German occupiers beginning in earnest the following day, reaching their height on the 22nd.