If the events of 1830 and 1832 had already demonstrated that the influence of the national question spread far further than its former elitist public, ten years later on nationalism was finally established as a mass phenomenon. The breaking point was provided by the Rhine crisis of 1840, which was unleashed when the Thiers government in France attempted to compensate for the hard blow dealt to France's eastern policy and the ensuing crisis of nationalist fervour by instigating an aggressive eastern policy and propagating for the first time since 1815 the re-establishment of the Rhine as a ‘natural’ frontier.

The German reaction was very measured – to start off with. The cabinet ministers of the leading states in the German Confederation, headed by Prince Metternich, the Austrian Court and State Chancellor, conducted themselves wholly in the tradition of the Congress of Vienna by attempting to ‘denationalise’ the question of the Rhine frontier and to treat it as a matter involving all the European powers. Metternich in particular had reason to fear the nationalistic motives behind French policy, in which he could see the revolutionary principle directed against the European system of peace. German public opinion responded equally moderately on a purely academic and rhetorical level, as always when the national question was raised. The Rhineland newspaper reports about the debates in the Paris chambre des députés and about the signs of a French mobilisation were almost devoid of emotion, whereas the South German press was already engaged in a lively campaign against ‘our neighbour's treacherous intentions’, explaining in innumerable articles that France's demands for a new frontier affected not only Prussians, Badeners or Bavarians, but all Germans.