A private photo album of  27 small snaspshots was purchased in April 2013 of behind–the–scenes at the filming of Der Große König. Two of those album pages  are shown here:

Here is a close–up of the behind–the–scenes moment when the soldier played by Gustav Fröhlich is tied to the wagon wheel as a punishment for disobeying orders:

Here is the original Ufa studio invitation for the world premiere of the film in 1942: