Secret-rated lithographed map of France and the Low Countries, showing U.S. intelligence about the disposition of Wehrmacht offensive and defensive forces on the eve of D-Day. The map was issued as part of the famed and very highly sought-after Neptune Monograph.
The map illustrates the presumed positions of 53 divisions spread across France, Belgium, and the Netherlands. It would have been very useful to soldiers and commanders on D-Day as they encountered German defenses. If units were spotted out of place it could have indicated prior German knowledge of the landings or other strategic changes.
This map must have reflected the best intelligence available to Allied war planners in mid-April, 1944, less than 8 weeks before the planned landings. The data was presumably compiled from a host of sources: reconnaissance overflights, monitoring of German radio traffic (including that encoded by the vaunted Enigma machine, long-since broken by Bletchley Park), and reports from Free French forces and spies working in Occupied France.
Though sparse in content, the map is revelatory of the progress of the Allied war effort. The presence of the SS Hitler Jugend (“Hitler Youth”) division in reserve south of Rouen is indicative of how the Russian Front was bleeding the Wehrmacht dry, requiring ever more aggressive efforts to field a fighting force (By war’s end, of course, Berlin would be defended by units of teenagers—even adolescents—and of men in their sixties.)
The distribution of German forces is indicative of the great success of Operation Bodyguard, the epic effort to divert Hitler’s attention from Normandy and, after the landings, convince him that they were a mere diversion. The map clearly shows German units distributed up and down the French coast, reflecting their strategic uncertainty about the destination of the landings they knew to be coming. In this regard, the division at Calais, with three in reserve is well worth noting. One of the key objectives of Bodyguard was to “sell” Hitler on Calais as the target of the main landings.