This chapter explores the relationship between political developments in Bohemia from the 1790s to the 1880s and the concept of fidelity to “authentic” texts and music (Werktreue) in Mozart’s operas. The idea of Werktreue appeared in Prague in the 1790s in response to Bohemian patriotism and negative attitudes to the central government in Vienna. In the 1820s, Czech nationalists embraced similar attitudes in approaching Don Giovanni, and both the first Czech production of 1825 and the first production of the work at the Czech National Theater (1884) showcased the opera with musical numbers that were cut in contemporaneous German productions. German-Bohemians appropriated Werktreue as well but understood “authentic” performances of Don Giovanni as a link to the ideals of a pan-German national culture. By the time of the 1887 Don Giovanni centennial celebrations, however, some German-Bohemian critics considered Werktreue in Mozart’s operas antithetical to true German art under the influence of Wagnerian ideas.