On 4 February 1923, French troops occupied the towns of Appenweier and Offenburg, which meant that the slow passenger trains ("Bummelzug") were forced to start and end their runs in the community of Ortenberg, just south of Offenburg. Only one express passenger train, traveling between Hausach and Konstanz, utilized the line at the time. All the usual through traffic on the Black Forest Railway had to be rerouted in complicated fashion. Only on 11 December 1923, when Appenweier und Offenburg were liberated, did regular service to Offenburg, and limited service further north, resume.