Prussia exerted pressure on the Regent to vacate the office that he had resigned, but the Archduke insisted that he would remain out of a sense of obligation, and had powerful backing from Austria's Prime Minister, Prince Schwarzenberg, who was eager to stifle Prussian ambitions in Germany. Nevertheless, he departed for a prolonged stay at the health resort of Bad Gastein. At this point, the National Assembly was reduced to a rump parliament led by radicals and in opposition to the Regent. The Regency existed in name only, though the Archduke continued formal correspondence with Vienna and Berlin as such. He finally was allowed to resign from his office on 20 December 1849. When Archduke John came back to Frankfurt on a visit in 1858, he openly regretted the failure of the German unification.