By the way, while most historians refer to the period between WW I and WW II as "the interwar years," in Germany, that era is called "Halftime." (Badda-boom!)
Never heard of that term, and I am a historian by profession.
Oh, and the Deutschlandlied‘s words were an exhortation, yes, to estimate the whole country, not just the numerous principalities and kingdoms created by the Congress of Vienna which constituted the German Confederation.
Heinrich Hoffmann von Fallersleben, the author, wanted a German republic in the style of France, with popular sovereignty in the British-American mold.
That was not going well with the neo absolutist princes and princelings, so Hoffmann went into exile. In the German Revolution of 1848/9, at last a big step was done towards democratic rights.