During the occupation of France in 1940, the Germans viewed the battles in Alsace and Lorraine as a battle for liberation and these provinces once again returned to Germany.
French stamps continued in use until 17th August 1940. On 15th August 1940 German stamps of Hindenburg series were overprinted "Elsaß" and placed on sale in Alsace along with pre-paid postcards. These stamps were also valid for use in Lorraine, Luxemburg and Germany. From 1st January 1942 only stamps of the German Reich were valid in Alsace.