To the north, the strait of the Baltic Sea known as the Little Belt (Danish: Lillebælt) ran alongside the ethnically mixed Danish Duchy of Schleswig, part of an area subject to a highly complex dispute, known as the Schleswig-Holstein Question, between Denmark and its neighbors. After the Second Schleswig War in 1864, the Danish-German border ran through the strait until 1920, but ultimately, the Schleswig Plebiscite moved the border to its current location, south of the Little Belt.
In the south, the Adige river (German: Etsch) runs to the Adriatic Sea. In 1841, the Austrian Empire ruled all of its length, and much of the population of its area was German. Historically, the river was the southern border of the medieval Duchy of Carinthia, and centuries later it marked the border between Austrian Venetia and Napoleonic Italian Republic; in the middle, it was divided among the Republic of Venice, the Bishopric of Trent and Austria. After the Austro-Prussian War of 1866, the river's southern part became part of Italy, while the northern one remained part of Austrian Tirol; but it then became part of Italy too, after 1918. Now, as then, the town of Salorno (German: Salurn), marks the linguistic border between the German and the Italian speaking population in the valley.
In the east, the lower part of the Memel, known in other languages as the Neman, was located within East Prussia, part of the Kingdom of Prussia, which actually stretched north beyond the river, and beyond the city of Memel (Klaipėda). In 1920, the area north of the river was detached from Germany and became known as Memelland. Only a few German speakers remained in the area after 1945.
In the west, the river known as the Maas or the Meuse ran through the Dutch-ruled and Limburgish-speaking Duchy of Limburg which was joined to the German Confederation between 5 September 1839 and 23 August 1866. The modern German border is close to the river in that area.
The line "Germany, Germany above all" meant that the most important goal of the Vormärz revolutionaries should be a unified Germany overcoming the perceived anti-liberal Kleinstaaterei. Along with the Flag of Germany, it was one of the symbols of the March Revolution of 1848.