“By your example, France didn't exist either” Louis the XIV wasn’t the King of France? That is new. So, what was his Kingdom names?

“for a longtime it was illegal to teach german, or provide state funds for german schools”: Sources? The main newspaper in Alsace is printed in Alsatian. And German is taught in French Schools. And the official language in France is French by the Constitution, so no German Schools will be financed by the State, nor Algerian, Russian, Portuguese etc. The “francisation” of France (when local languages were banned) happened after 1870 with the development of the school system (Laic and compulsory) under Jules Ferry, so Alsace was not French. It came back in 1918, and yes, the Germans forbade French when they occupied the territory.

“Hmmm very semantic statement”: Nope, it is the core of the problem. You claim that because the population speak a kind of Germanic language (as were the Franks, from where the name France comes from) that makes them German. You ignored the will of the population (the Alsatians Representative of the 1st Assembly of the 1st Republic, during the Federation Commemoration held on the 14th of July 1790, acknowledged and pledged the belonging of Alsace to France Territory.
France is not an ethnic, Religious or Language State. Borders changed, populations are various, so languages. It is a political contract based roughly on the values of Enlightenment and the Republic.

“Historically the population was German”: Based on what? So were the Franks.

“Even today, the French Cultural Department considers and lists them as French, German French, or French Speaking Germans” Sources? Because the French Constitution forbids distinction and that is why it is difficult to know Religion and Ethnic Backgrounds of the French Population (no distinction will be made blab la bla). You just made claim you cannot sustain. And such list will be done by the former “Renseignements Généraux” kind of internal half secret police, if it would be done.

And you still didn’t answer about where Hitler founded his idea in France.