In the late 1930s, Rosenberg, alert to signs of an approaching war, began quietly moving his collection out of continental Europe to the London branch and to storage in America (via the 1939 New York World's Fair), Australia and later to South America. He then stopped adding to his collection in France, and advised his artists to make similar arrangements. Although his relocation plans were well advanced, by the time of the 1940 Nazi invasion of France, he still held over 2,000 pieces in the country, both in his gallery and in storage. The Rosenbergs were Jewish and had to flee Nazi-occupied France. They owed their lives to the Portuguese Consul-General in Bordeaux, Aristides de Sousa Mendes, who issued them visas to his country.