Unterelsaß (also spelled Unterelsass, French: Basse-Alsace, meaning Lower Alsace) was the northern part of the historical region Alsace or Elsass, inhabited originally by locals speaking Alemannic German. From 1871 to 1918, Bezirk Unterelsaß was the name for the central district (Bezirk) of the imperial territory of Elsaß-Lothringen (Alsace-Lorraine) in the German Empire.
According to the census 1886 the district of Lower Alsace comprised:
The capital of the district was Straßburg. There were the 8 subdistricts ("Kreise") of
The flag is a white bar in a red field decorated on each side with a white lace motif. The union of this flag with that of Oberelsaß forms the flag of modern Alsace.
The district of Unterelsaß corresponds exactly to the current département of Bas-Rhin, but not to the Alsatian territory before 1870. Under the terms of a particular agreement that was signed in Berlin July 21, 1871, and in Paris July 31, 1871, 18 municipalities of the Vosges department were integrated into the new imperial district of Lower Alsace, subdistrict of Molsheim, canton of Schirmeck.
In earlier times Rothau, Wildersbach, Waldersbach, Neuvillers belonged to the principality of Ban de la Roche before they joined the département of the Vosges in 1790. The other ones were located in the former Duchy of Lorraine.
The inhabitants of these municipalities didn't and still don't speak any German dialect (Lower Alemannic) such as their neighbors. The linguistic boundary runs between Wisches and Lutzelhouse. The people of the annexed towns speaks a Romance language from the Langues d'oïl, Lorraine family, such as some municipalities in the district of Upper Alsace. This cultural particularity stresses the fact that the annexation of French territories by the German Empire not always referred to the pan-nationalist political idea (Pan-Germanism trying to unite all German-speaking people. When Alsace was recovered by France in 1919 it was decided not to return the 18 annexed municipalities to their former Department(Vosges). Thus in terms of departmental boundaries, the mountain region remains administratively separated from the western portion of the Vosges mountains. Nowadays the inhabitants of the Bruche valley basically identify themselves with Lower Alsatians regardless of their cultural identity.