In the 1920s, Germany witnessed a series of revivals of the operas of G.F. Handel, works which had almost entirely lapsed from the German musical consciousness in the nearly 200 years since the composer's death. The reemergence of Handel opera can be traced back to one man, Oskar Hagen, an Art History professor at the University of Göttingen who staged the landmark performance of Rodelinda in 1920. This performance and those that followed it were an unanticipated success, suddenly launching the performance of Handel operas across the country, and eventually, the world. Hagen's adaptation techniques, however, have been harshly criticized by modern scholars as being clumsy, audacious, and "inauthentic." This thesis focuses on Hagen's methods of musical adaptation and how they relate to the aesthetics of 1920s Germany, as well as the reception of Hagen's efforts and their impact on the performance practice of Handel opera in the twentieth century.