Short answers, pulled from the story.
German nationalism began around 1770, when philosopher Johann Gottfried Herder developed the concept of nationalism. Historians note that earlier forms were already present around 1500, but Herder gave the movement its theoretical foundation.
The German question was the 19th-century debate over whether a unified German nation-state should take the form of a Lesser Germany excluding Austria or a Greater Germany including Austria and its German-speaking territories. Prussian Chancellor Otto von Bismarck resolved it through a series of wars culminating in the Franco-Prussian War of 1870-1871, founding the German Empire in 1871 as a Lesser Germany with the King of Prussia as Emperor.
The Nazi Party fused extreme German nationalism with racial ideology, culminating in the 1935 Nuremberg Laws, which attempted to define by statute and genetics who was to be considered German. The Generalplan Ost called for the extermination, expulsion, Germanization, or enslavement of Czechs, Poles, Russians, Belarusians, and Ukrainians to provide living space for ethnic Germans.
The Sachsenspiegel was an early 13th-century German law book containing more than ten passages that explicitly referenced the German language, German lands, the history of the Germans, and German descent. Scholars regard these four categories as the first appearance of key features of national consciousness within a vernacular legal text of the Middle Ages.
German reunification was achieved in 1990, following Die Wende, the political transformation driven by the East German people in the late 1980s. The 1990 elections put a government in place that negotiated the Treaty on the Final Settlement with Respect to Germany, formally reuniting East and West Germany.
Due to post-1945 repudiation of the Nazi regime and its atrocities, German nationalism has generally been viewed in Germany as taboo. A 2011 article from the University of Pennsylvania stated that patriotism had been a taboo topic since the time of Adolf Hitler, with the vast majority of Germans accepting they could not express national pride, though the Correlates of War project finds contemporary surveys of German patriotism rank at or near the bottom among nations.