War broke out in September 1939 and for most Parisians there were few immediate changes. That was not the experience of several thousand German political refugees who had sought refuge from persecution by moving to Paris, however. Leo Bauer was among those arrested in Paris in September 1939. He was held in a succession of internment camps between then and the Franco-German armistice of June 1940. In July 1940 he managed to escape to Switzerland with his party comrade . In Switzerland he lived illegally under the identity of a bank employee in Geneva and the name "Paul-Eric Perret". He became a Communist Party informant/contact ("Vertrauensmann") in West Switzerland and took part in "frontier work" involving the Franco-Swiss border.