The same year brought his expulsion from Göttingen in consequence of his protest, in conjunction with six of his colleagues, against the violation of the constitution by Ernest Augustus, king of Hanover and duke of Cumberland. After several years in Heidelberg, Darmstadt and Rome, he settled permanently in Heidelberg, where, in 1844, he was appointed honorary professor. He zealously took up in the following year the cause of the German Catholics, hoping it would lead to a union of all the Christian confessions, and to the establishment of a national church. He also came forward in 1846 as a patriotic champion of the Schleswig-Holsteiners, and when, in 1847, King Frederick William IV promulgated the royal decree for summoning the so-called United Diet (), Gervinus hoped that this event would form the basis of the constitutional development of the largest German state. He founded, together with some other patriotic scholars, the "Deutsche Zeitung", which certainly was one of the best-written political journals ever published in Germany. His appearance in the political arena secured his election as deputy for the Prussian province of Saxony to the National Assembly sitting in 1848 at Frankfort. Disgusted with the failure of that body, he retired from all active political life.