France long sought to attain and then preserve what it considered to be its "natural boundaries", which is regarded as the Pyrenees to the southwest, the Alps to the southeast, and the Rhine to the northeast.

These border changes at the time meant more or less that one ruler (the local princes and city governments, with some remaining power of the Holy Roman Emperor) was exchanged for another (the King of France).

German nationalism, on the other hand, which in its 19th century form originated as a reaction against the French occupation of large areas of Germany under Napoleon, sought to unify all the German-speaking populations of the former Holy Roman Empire into a single nation-state.

In the perversion of their French life, they have no exact idea of what concerns Germany.In 1871, the newly created German Empire's demand for Alsace from France after its victory in the Franco-Prussian War was not simply a punitive measure.

[9] The German Emperor, Wilhelm I, eventually sided with army commander Helmuth von Moltke, other Prussian generals and other officials who argued that a westward shift in the French border was necessary for strategic military and ethnographic reasons.

At the time, ethnic identity was often based primarily on language, unlike today's more multifaceted approach focusing on self-identification.

From a military perspective, by early 1870s standards, shifting the frontier away from the Rhine would give the Germans a strategic buffer against feared future French attacks.

Due to the annexation, the Germans gained control of the fortifications of Metz and Strasbourg (Strassburg) on the left bank of the Rhine and most of the iron resources of Lorraine.

[verification needed] Many Germans at the time thought that the unification of Germany as the new Empire would in itself be enough to earn permanent French enmity and thus desired a defensible border with their long-standing enemy.

That small francophone areas were affected was used in France to denounce the new border, since Germany had justified the annexation on linguistic grounds.

On 22 June 1877, Eduard von Moeller, the first governor of Alsace–Lorraine, decreed that 90 place names in the district of Lorraine were to be changed from their French to the German forms.

The population was also not asked for its opinion on state affiliation in 1918 when it returned to France.The Protesters rejected both cooperation with the German authorities and constructive political work in the Reichstag.

In the countryside and the predominantly French-speaking electoral districts of Lorraine, the Autonomists remained strong, while in the cities, especially Strassburg, they increasingly played only a subordinate role, with the Social Democrats dominating.

The southern regions of the Imperial Territory belonged to the districts of the XIV Army Corps, which was made up in 1871 of troops from Baden.

Alsatians and Lorrainers who were called up for military service were distributed among all Prussian Army units, as were active and passive social democrats, who were also considered to be politically unreliable.

The assaults led to a Reichstag debate on the militaristic structures of German society and strained the relations between Alsace–Lorraine and the rest of Germany.

[32] Until the First World War, the Imperial Territory experienced a great economic boom, and many new socio-political benefits such as social security and health insurance were introduced in line with developments in the rest of the German Empire.

Although the proportion of native speakers of German dialects in the new Imperial Territory was around 90%, Catholics in Alsace–Lorraine tended initially to be sceptical about the ethnographic unification with Germany, which had come about under the leadership of predominately Protestant Prussia.

The dispute reached a climax when, on 3 August 1873, a pastoral letter from the Bishop of Nancy-Toul calling for prayers for the reunification of Alsace–Lorraine with France was read in the Alsace–Lorraine districts of Château-Salins and Saarburg, which still belonged to his diocese.

The Protestants traditionally had a positive image of Germany, while after the Dreyfus affair, the Jewish population regarded France with extreme suspicion.

[35] In French foreign policy, the demand for the return of Alsace and Lorraine faded in importance after 1880 with the decline of the monarchist element.

[36] The increased militarization of Europe and the lack of negotiations between major powers led to harsh and rash actions taken by both sides in respect to Alsace–Lorraine during World War I.

The governor stated in February 1918: "Sympathies towards France and repulsion for Germans have penetrated to a frightening depth the petty bourgeoisie and the peasantry.

In this chaotic situation, Alsace–Lorraine's state parliament proclaimed itself the supreme authority of the land with the name of Nationalrat, the Strasbourg Soviet proclaimed the foundation of a Republic of Alsace–Lorraine, and Jacques Peirotes, the SPD Reichstag representative for Colmar, announced the establishment of French rule, urging Paris to send troops quickly.

The Nationalrat proclaimed the annexation of Alsace to France on 5 December, but the action was not internationally recognized until the Treaty of Versailles was concluded in 1919.

France divided Alsace–Lorraine into the départements of Haut-Rhin, Bas-Rhin, and Moselle (the same political structure as before the annexation and as created by the French Revolution, with slightly different limits).

[j] The French government immediately started a Francization campaign that included the forced deportation of all Germans who had settled in the area after 1870.

On 1 September 1939, the day World War II started, residents of Alsace and Moselle living in the Franco-German border region were evacuated.

Many others fought in Normandy against the Allies as the malgré-nous of the 2nd SS Panzer Division Das Reich, some of whom were involved in the Oradour sur Glane and Tulle war crimes.

[51][52] When Alsace and the Lorraine department became part of Germany, the French laws regarding religious bodies were preserved, with special privileges to the then recognised religions of Calvinism, Judaism, Lutheranism and Roman Catholicism, under a system known as the Concordat.