Theodor Mommsen is one of the central figures in the history of ancient historical science. For a long time, any engagement with Rome took place in his shadow. However, in 1912, the young Swiss scholar Matthias Gelzer published a habilitation thesis in which he radically distanced himself from the constitutional lawyer Mommsen in the name of a progressive social history. Gelzer's rebellious polemic later provided subsequent researchers with a welcome opportunity to break away from the feared patriarch. By referencing Gelzer, one could align with the progressive side and set Mommsen aside. Simon Strauss now decisively questions this approach and argues that many aspects of social history are already addressed in Mommsen's work—particularly in his Roman Constitutional Law published between 1871 and 1888. Gelzer's contributions can be viewed in this light.