In The Fall of France: The Nazi Invasion of 1940 by Julian Jackson (Oxford University Press: New York, 2003), Jackson discusses French preparations for a German offensive, and states that the French did not expect a major offensive through the Ardennes. Jackson quotes Pétain declaring the Ardennes impenetrable, because "If any enemy attacked he would be pincered as he left the forest. This is not a dangerous sector... as long as we make special provisions" He also quotes Gamelin stating that the Ardennes had "never favored large operations."
Jackson then goes on to mention a map exercise conducted by the French in 1938 in which they estimated that it would take the Germans roughly 60 hours to move armored forces through the Ardennes, which is approximately how long it took them.
I've checked Jackson's notes in the back, but I can't figure out what these map exercises were.
Can anyone figure out which map exercises Jackson is talking about?
Also, what really is the correct narrative here? I've often heard it stated that the French believed the Ardennes impassable for armored units. Is it this? Or is it Jackson's nuanced narrative, where the Ardennes was impenetrable if "special provisions" were made?
For reference, everything that I am discussing is in the last paragraph of page 32.
The map exercises in question were conducted by General André-Gaston Prételat, the commander of Second Army between May-June 1938. As Jackson describes, Prételat's exercise estimated that it would take sixty hours for a tank-armed aggressor to cross the Ardennes. Nor was Prételat alone in his estimation of the Ardennes's suitability for tanks; a Colonel Bourguignon wrote in a study of frontier reconnaissance that the area was vulnerable to a surprise tank thrust.
The French high command was largely indifferent to these concerns. Gamelin accused Prételat of too much pessimism in his map exercise and felt that existing troop levels would be more than enough to staunch a German assault through the area. The provisions Petain staked defense on the region upon were special blocking troops of the French army and cooperation with the Belgians. Both of these would be sufficient to hold an unlikely German Ardennes offensive until the bulk of French forces could meet it and destroy the offensive in a set-piece, methodical battle. The French high command estimated that because of the roads and geography, a German attack would likely take nine days to clear the forest and two weeks to reach the Meuse. If a German attack were to materialize in this sector, then the French high command believed they would have ample time to organize an efficient counterattack. In addition to dismissing Prételat's exercise, Gamelin also restricted access to the results of the map exercise lest it create panic among the lower ranks over German capabilities.
Hindsight has rendered both Gamelin and Pétain rather foolish over this myopia over the Ardennes, and with a good deal of justification. Nonetheless, the German experience in the Ardennes does add some weight to the French military chiefs' skepticism of the Ardennes suitability for a quick thrust. Gelb created massive traffic jams in the area and the offensive did dance on the edge of disaster at a few critical points during the campaign because of road bottlenecks. French intelligence and aerial reconnaissance largely failed to pick up the build-up in the Ardennes and the French high command tended to dismiss those few reports that did indicate something was up in this sector. The French rigid system of command and control also denuded what little initiative the local blocking troops possessed to meet the upcoming onslaught. Additionally, Franco-Belgian cooperation in the Ardennes proved anything but unified with the Belgians evacuating areas with the false expectation French troops would take their places. This was in stark contrast to German troops who had a much more flexible approach to military operations and a unified command more attuned to the realities of the situation.
Sources
Citino, Robert Michael. Death of the Wehrmacht: The German Campaigns of 1942. Lawrence: University Press of Kansas, 2007.
Dildy, Doug, and Peter Dennis. Fall Gelb 1940 (1): Panzer Breakthrough in the West. Oxford: Osprey, 2014. 2014.
Epstein, Jonathan A. Belgium's Dilemma The Formation of the Belgian Defense Policy, 1932-1940. Leiden: Brill, 2014.
Frieser, Karl-Heinz, and John T. Greenwood. The Blitzkrieg legend: the 1940 campaign in the West. Annapolis, Md: Naval Institute Press, 2005.
Nord, Philip G. France 1940: Defending the Republic. New Haven: Yale University Press, 2015.