This post has nothing to do with the Dams Raid or 617 Squadron. However, it shows a valuable resource which might be useful to anyone doing research into any Second World War air campaign.
McMaster University, in the fine city of Hamilton, Ontario, Canada, has digitised a number of maps and charts from the wartime period. Above is one which shows Western Europe from the Irish coast to Stettin, running from La Rochelle in the south to Uppsala in the north. This covers most of the areas in Germany targeted in the 1940-45 bomber campaign.
The highest resolution of this particular chart runs to a stonking 1.5 gigabyte file and takes a while to download as a tiff, with a resolution of 26177 x 19157 pixels. But it has a great level of detail, as you can see from this crop of the Dutch coastline:
[Thanks to user JDCave on the RAF Commands Forum for the tip.]