. . . "Grand Duchy of Frankfurt"@en . . . . . "The Grand Duchy of Frankfurt was a German satellite state of Napoleonic creation. It came into existence in 1810 through the combination of the former territories of the Archbishopric of Mainz along with the Free City of Frankfurt itself."@en . "The Grand Duchy of Frankfurt was a German satellite state of Napoleonic creation. It came into existence in 1810 through the combination of the former territories of the Archbishopric of Mainz along with the Free City of Frankfurt itself."@en . .