After the beginning of the war, Richard Wendelstadt set up a military hospital on the upper floor of the house, which was medically supervised by the physician Hermann Wendelstadt (1862-1928), a brother of Richard. After Richard’s death, Hermann Wendelstadt sold the Redoute on January 22, 1920, including the grounds of 25 acres for 1.15 million marks to the municipality of Godesberg, which wanted to use it as a location for cultural functions. Some valuable furnishings remained in the possession of the Wendelstadt family and were moved to their villa in Schweinheim.
In 1925, the municipality of Godesberg added the Garden Ballroom to the Redoute, using plans from local architect Walter Bühling (1887–1955) under the supervision of conservator Edmund Renard. In the same year, the entrance gate at the Brunnenallee was installed in conjunction with the Rhineland millennial celebrations. It was made by local iron craftsman Gottlieb Gernhard (1889–1967). For some time, the “Redüttchen” was used as a pharmacy.