Hm.. the fortresses were not stood up until the Cezch Crisis in October 1938.
This is hardly surprising as the
whole of the French military was at a rather poor readiness until the October '38 crisis. Maybe if they had spent some of the money for the maginot line on their actual forces instead they wouldn't have been at such a poor readiness.
Plus, it says nothing about the quality of troops.
A quick check of the map shows approx 40% of the French field armies would be required to hold that length of ground.
Based on what? Even without the Maginot Line, the German's are not going to be throwing anything other then holding attacks down there. Maginot Line or no, the main German thrust - as in WWI - was going to come through Belgium. The Germans were never going to throw their main thrust through the south due to the closed terrain, pre-existing fortress cities (like Metz), and most importantly because south of the Ardennes means they have to cover several hundred more km of ground to reach the Channel. The Maginot Line defended an axis that even
before its construction in WWI, the Germans had shown a disinclination to use.
Take another look at Horne & count the size of the group sent into the Ardennes on 10 may. Five of the Mechanized cavalry divisions, reinforced with motorized units from the divisions and corps troops of the 2d, 3rd & 9th Armies. Since the French sent a mechanized/motorized force into the area it sort of contradicts the idea they thought it impassable to such a force. They were also aware the Belgian army had assigned a large portion of its motorized formations to the same area. They had sent two armies into the area in 1914 & that experience appears in the French army literature of the interwar years.
Between the four Belgian divisions assigned & the French mechanized force the Ardennes should have been well defended. Why these units failed is not because the region was misjudged but lays in other directions.
None of this at all matches the actual French dispositions; the First French Army Group included the First, Second and Third Armies. The First Army had some of France's best troops, including all of France's armored formations, and was directed to advance into central Belgium. To the south of First lay Ninth Army which covered the western side of the Ardennes, down to Sedan on its right flank. And then to the south east of the Ninth lay the Second Army, with Sedan on on its left flank, and then extending down to the Second Army Group holding the Maginot Line, proper.
The closest of these that could be described as "defending the Ardennes" is the 9th army, whose OOB for May 10th gives it one motorized division, two light cavalry divisions, and 7 infantry divisions. And given the grand total of the Belgian motorized capabilities consisted of the 1st Ardennes Chassiers division, the fact they deployed down around the Ardennes is non-indicative. In the part of the Ardennes where the German
schwerpunkt was, the only forces were elements of the Belgian 1st
Ardennes Chassiers and 5th French Light Cavalry which, to quote wiki, "had insufficient anti-tank capacity to block the surprisingly large number of German tanks they encountered and quickly gave way, withdrawing behind the Meuse."
The movement of
all French reserves makes clear where Gamelin's focus lay (if the text of his various orders and reports over the period left any doubt - which it does not). Between 10 and 14 May Gamelin committed a total of 13 divisions from his reserve to battle. Of these five were sent to First Army, and eight to Second Army, four of which were engaged (disastrously) on the fringes of the German breakout. But to the
center of the German effort, defended by the Ninth Army, Gamelin sent not one division from the central reserve. Certainly Second Army was involved in some bitter fighting attempting to hold Sedan, but it was against only a portion of the Ninth Army that the full force of the German breakout was aimed. Finally on 15 May Gamelin began to redirect some forces from First Army to Ninth, although by then it was much too late.
Even on 15 May, when the German breakout was a reality, Gamelin continued to badly misread it's intent. The going opinion at his HQ at Vincennes was now that the Germans would swing left into Second Army, outflank and roll up the Maginot Line. This poor assessment meant that even though several more divisions were moving to Sedan their orders continued to anticipate that the Germans would swing
south. As a result, what force the French had left in the sector was out of position to block the Germans when they instead moved west and north - through Ninth Army.
The French military command simply couldn't believe the Germans would do anything so ambitious. Gamelin and Georges thought in terms of a war of cautious steps, not grand thrusts. In fact, the only person in the French hierarchy who seems to have realized that the Germans might actually launch a more ambitious penetration was Prime Minister Reynaud. On the morning of the 15th, Reynaud personally rang Churchill, "evidently under great stress," according to Churchill's account, to inform him that the French front had been broken at Sedan, and the Germans were pouring through and could soon be in Paris. Extremely concerned, Churchill immediately rang the BEF, and was informed by General Ironside that Gamelin had issued them no further orders and assured them that all was in hand. Churchill then rang General Georges directly. Georges "seemed quite cool, and reported that the breach at Sedan was being plugged." Considering Reynaud (the politician) to be a bit overwrought, Churchill accepted the word of Georges (the soldier).
Finally, on 16 May Gamelin awoke to news that German Panzers were closing on Laon, just 82 miles from Paris. Vincennes went into a panic, and Gamelin began issuing frantic orders to redirect everything (which would have been unnecessary if the
shwerpunkt had been correctly identified on the 11th). Even then, the French assumption was that the target was Paris itself, as opposed to the encirclement and destruction of the Army in Belgium. Thus it was actually not until 18 May that the French realized the Germans were going for the Channel, not Paris.
They gambled that a half dozen mobile divisions could seize & exploit multiple bridgeheads from two enemy armies with three times as many divisions, five time the artillery strength, and mostly defending from prepared positions.
Except in reality, the German
schwerpunkt did not face the entirety of two armies. As you can see below, the broad front of the German breakthrough largely conforms to the boundaries of Ninth Army, the French force that received the least (no) reinforcements in the critical days between 11 and 14 May, and on which front lay the actual center of gravity.
And see Stonne to the south of the red bulge on the map? That's where Second Army threw all its reserves. Whoever held Stonne would have a commanding view of the Sedan bridgehead, so it was an important position, but it wasn't the center of gravity. As the map shows, the Germans crossed on a wide front, of which Sedan was only the largest crossing. The problem is that the French committed to the
south of Stonne, while Guderian just left two divisions behind to keep them busy, and then moved the rest of his forces away to the north west. You can see it clearly on the map. So even those forces at Sedan were oriented to block an advance in the wrong direction.
Put together, on May 10th the Germans moved through the Ardennes with nearly the entirety of Army Group A for a total of 8 panzer divisions, 3 motorized infantry divisions, 27 infantry divisions, and 1 mountain division (a total of 39 divisions) against the elements of a single Belgian motorized and a French light cavalry. Afterwards, the German main effort lay into Ninth Army, which had a total of 10 divisions. Thus, your proclaimed force estimate is actually inverted: it was the French who were outnumbered more then 3:1 during the critical breakthrough phase and not the other way around.
Air recon missions were overflown on the 10th May, there were reports from before dawn 10 May from a French officer stationed in Luxemborg,
Which were largely ignored by higher command. In fact, as late as 15 May Gamelin still believed the German "
schwerpunkt" was further north in Belgium in the Gembloux area. On 11 May when the first reserves were sent to the Sedan area, Gamelin still believed that the effort in the Ardennes was a spoiling attack. He (or rather Georges, because Gamelin limited himself to tacitly accepting his deputy's maneuvers) committed reserves to the fight on the Meuse out of prudence, but therafter his full attention remained further north. After reviewing Georges actions he went to bed stating "The defence now seems well assured along the whole front of the river [Meuse]." Gamelin himself later admitted that he didn't realize how grave the situation at Sedan was, though he blamed poor reporting from the field on his ignorance.
five mechanized cavalry divisions were sent to find the Germans in Luxembourg and the Belgian Ardennes on the morning of 10 May.
The Germans certainly didn't encounter anything like five mechanized-cavalry divisions during their dash through the Ardennes and French records do not show them deploying that number of forces into the Ardennes.
All three of the new DCR type armored divisions were sent from the Stratigic Reserve to reinforce the 2d & 9th Armies facing the Ardennes, not elsewhere.
Except this is false. All three of the DCR armored divisions were initially employed with first army, where they actually stalled the German advance at Hannut. But the French victory at Hannut was totally undermined by the concurrent German breakthrough at Sedan to the south, forcing them to abandon the field and begin a ruinous 200km dash south to try and stop Guderian's panzers.
) or you can spend it on something else. Assume that you spend it on weapons... you still have the same basic problem: how can you protect the country against a surprise attack? How can you stand at least two weeks to allow mobilisation?