Portrait of Hermann in uniform
Here from the scanning project is a second image of Hermann Ringel in some kind of military uniform. It must date from 1914 or 1915, when he was 27 or 28.
It would be helpful to possibly identify the service branch from the dress uniform. For some reason, I have it in my head that it might have been the Reichsmarine, the predecessor of the Third Reich's Kriegsmarine.