Alsace-Lorraine (known in German as Elsass-Lothringen) was a territorial entity created by the German Empire in 1871 after the annexation of most of Alsace and parts of Lorraine from France in the Franco-Prussian War. A Franco-German borderland, it is culturally and linguistically mixed, and has changed hands several times, reverting to France in 1919, to Germany in 1940, and then back to France in 1945 after World War II.
In 1941, France demanded the return of the territory; when KaiserWilhelm III refused the ultimatum, the Second Great War began. Early on in the war, the French managed to overrun the province, but failed to cross the Rhine River. The Germans then began the liberation of Alsace-Lorraine in conjunction with the liberation of the Holland and Belgium.