Hello Jan

I like too the historical maps.

My comments:

Added to others you receive here.
If you want to make this work with a computer program.
To begin with the map, you'll need a reference, by example, an Atlas from you can copy coastal lines, rivers, lakes, etc. The scale is important, maybe in this particular case, you'll need to join several pages of this atlas. The size is not important, but you have to know the scale (by example 1:10.000) cause is a good habit to place it in the finished map. Once you had made this basic-map, that you can keep for further maps as a mother source, is better to reduce the map size (not the scale) to the actual size it will have in this occasion.
(I think the mountains between France and Spain are not properly represented cause, as the Alps, are youngs and have to be pointed)
In this new stage is important to get the historical data (by example in an or several history atlases) from you'll copy the political limits, cities, and all you need.
The colours are, of course importants and the most important section to control is the legibility, essential in a map (It is my opinion).