I am trying to geo-reference a series of maps of the German Military service in ArcMap or ArcGIS Pro using the coordinate grid (in red) provided by the German Military during the WWII. The attached map is an example of the maps (125 in total) which I would like to digitize. While I have some experience in geo-referencing maps, it is the first time I am using an original grid of the map to do so.
As far as I understood so far, in order to enter the coordinates displayed on the map. I should first understand the original georeferencing system. However, unfortunately so far I have not been able to find its history.
Are there perhaps other correct methods to digitize these maps?
How would you go about digitizing these maps?