What if Germans executed original plan for case yellow?

The original case yellow devised by the old guard generals in the OKH predicted similar route as in the WWI through the Low Countries into the northern France.Using one instead of two arcs later conceived.Fortunately for the Germans an unlikely event happened when Hellmuth Reinberger a major in fallschirmjager, lost his way in bad weather and landed in Holland.On him he had complete and approved plans for case yellow that were to be delivered to 2. Luftflotte Headquarters..the plans quickly found the way to the French.Capture of the plans convinced stupid French commanders that the attack was going to unfold exactly as they predicted,while the Germans of course immediately started to change their compromised planes.In the second planning a simple and brilliant plan devised by junior officer (by General Staff standards anyway) von Manstein was adopted.This plan decided the battle for France before it even begin..

But what if the weather was better that fatal day or good Hellmuth was a better pilot,anyhow if the plans reached 2. Luftflotte instead of the French?
The Germans would then swarm across the Low Countries on a relatively narrow front between the Ardennes and the see,just like the Allies expected,head on into the French First Army Group,the cream of their army+BEF.The real events showed that first army group did pretty good in front of German army group B,practically bringing their advance to a halt until Germans turned their right flank at Sedan and Dinant when they were ordered to retreat.But the original plan did not predict attack through the Ardennes and across the Meuse.Therefore they would be entangled in a frontal fight with tightly packed French units that were superior in number of tanks and artillery.
In such situation Germans would still have these advantages:
-Army Group A would join the fray on the section of the front where in reality only Army Group B operated.Also A.G. A was the cream of the Wermacht,with most of the elite panzer formations,while A.G. B was pretty light in armour compered to Group A.
-Germans had more advanced battle doctrines,concentrating their firepower on narrow sections of the front and exploiting created gaps in contrast with outdated French military thinking of equal dispersion of forces across the entire front and holding a static defensive line while relinquishing the initiative to the enemy
-Germans had better quality and quantity in certain key arms branches,especially airplanes(fighters and tactical bombers) and specialised weapons like anti-tank and anti-aircraft guns
-Better tactics in armor,infantry or air battles
-Professionalism of Wermacht was something French could only dream about
-And last but probably decisive, air superiority and excellent ground support air arm(in my opinion key to the blitzkrieg).
In this case it would take much longer than some 2 weeks to take out French first army group,as was the case in fact,and it would be a bloody job probably claiming several hundred of thousands German casualties and vast quantities of equipment.During this time more French troops would raise behind the Somme,more colonial and British reinforcements would arrive and bloody German noses even more.Eventually Allies would loose almost for sure.

Now,what could the Allies do to perhaps even the odds somewhat,and I'll try to keep it within realistic parameters which could easily occur?If they achieved only three 'enhancements', things would look rather different.
-If French weren't satisfied,as they were,that over 60 of their divisions are looking from safety of impenetrable Maginot line to just 19 of Leeb's Heers Gruppe C,fifty or do French divisions could be redeployed to the critical,'live',sectors of the front.
-In accordance with their backward doctrines French High Command dispersed all of armored and mobile strategic reserves evenly across the front prior to the battle leaving only five infantry and one light armored division as a strategic reserve in whole northern France!French had 11 armored divisions,with another few being formed,plus a number of motorized formations.If at least half or two thirds of these units were held back to seal the cracks in the already strong line by determined counter attacks,Germans would have a though job.
-If British had been committed fully in air war over France(they contributed with just 100 engines) as they were fighting the battle for Britain,together they just might deny the Germans their complete air superiority,and deprive them of their greatest luxury..When things get rough(resistance get determined or counter attack hits the flanks) ,stukas fly in and problem is solved..
With these eventualities- no proper air superiority everywhere,going head on into massed Allied armies,German advance would be very slow and costly.And when a crack appears and elements of panzer division break through,they are met by superior numbers of counter attacking French tanks,with heavy Char B in lead(for which Germans had no answer except 88 mm flak,or to take them from behind). In this case Germans would bleed,with enormous casualties in man and equipment.Destroying First army group would probably take many months,giving even more time to Allies to mobilize their defensive potentials.Perhaps,Germans would still be victorious(only a super computer simulation could tell ),but that shock effect that crashed French will to resist and pushed their leaders on colaboration path ,just wouldn't be.So even after defeat,perhaps French would withdrew to their colonies,with the army and fleet,strongly shifting the balance of power in Mediterranean,Atlantic and North Africa to Allied side and forcing already exhausted Wermacht to station massive reserves to guard the southern flank of 'Festung Europa'.Who knows how the war would then look..
Thanks for your attention

 

If I understand things correctly, most of the French forces at the Maginot Line were tied to their posts and lacked the mobility to be shifted to another position so that option's out. As you've pointed out, the French Army didn't really have a strong mobile reserve because of the tactics they used so the Germans retained a strong advantage.
I agree that if the Germans didn't change their plans, it would've been a more bloodier fight. A longer fight would probably stiffen French resolve, even if the Allies were losing ground slowly because it would give time for the Allies to learn from their mistakes and improve their doctrines and tactics. Would this be enough to turn things around? That would be hard to call because in this case, the discussion would have to factor in the mindsets of the political figures who held the reigns of power at that time.

 

French reconnaissance and intelligence could assess how many divisions are opposing them in which sector,even approximately.Then common sense dictates that if you are defending especially from the most formidable fortifications in the world,you do not need 3 times as many soldiers as the enemy.More likely you'll need 3 times fewer.Therefore those troops could be easily timely shifted by foot to the part of the front with no prepared defenses and where most enemy units are concentrated.
About the mobile reserves..Initially French kept 22 divisions in reserve including 3 DCRs(heavy armor divisions),and then just prior to action shifted 13 of these formations to first line including 2 DCRs.So idea of armor reserves did exist in certain form in French military thinking,they were just panicking and acting irrationally.Since this is a 'what if scenario' ,it's not so impossible to imagine a little more courage in the creation of armored reserves instead of their panic.

 

I've got here a list & map from a old French magazine artical showing the distribution of the French army on may 1940. Heres is a rough description.

In the 'Maginot Line', from Longwy to Lauterbourg on the Rhine or the Third Armys sector, there were 18 infantry divsions. In quality they were 8 third wave 'B' divsions, 5 second wave 'A' divsions, and 4 first wave or 'R' divsions. There was also the British 51st Highland Divsion.

Behind the Third Armys sector were 7 infantry divsions designated as part of the "Stratigic Reserve".

To the south along the upper Rhine were 6 infantry divsions. 3 more infantry divsions attached to the stratigic reserve were behind the upper Rhine zone or the Fourth Armys sector

In the lesser fortified zone or Second Armys sector that ran from Longwy to Mezieres there were 4 infantry divsions and 2 light armored cavalry divsions. 3 infantry divsions, 1 motorized infantry divsion, and 1 heavy armored divsion (DCR) were to the rear & attached to the Stratigic Reserve. Also to the rear were 2 heavy armored divsions and 1 infantry divsion that were part of the general reserve of First Army Group. First Army Group was the force designated to advance into Beligium.

From Mezires north to Givet and west to Vervins was the Ninth Army with 5 infantry divsions, 1 motorized infantry divsion, 1 fortress divsion, and 2 light armored cavalry divsions.

Spread between the Oise & Escaut rivers was the First Army with: 4 infantry, 4 motorized, 2 medium armored cavalry (DLM) divsions.

Next came the BEF in the Lillie area. Technically this had 12+ divsions, but six were designated to lead the way into Belgium. 2 more partially trained divsions were to follow and back them up. The remainder were untrained and unequipped & were dispersed at construction tasks. 1 Armored divsion was being formed.

Last was the Seventh Army on the coast. 4 infantry, 1 motorized infantry, & 1 medium armored (DLM) divsion

Another dozen divsions including two Polish were distributed across the interior of France and along the Italian border.

Inside the fortifications were specialist regiments numbering about 40. these units were organized and equipped for manning the light forts or bunkers on the frontlines. They had no transport or field communications equipment. There were also the specialist units that manned the large forts.

So 18 out of nearly 90 French field divsions were in the 'Maginot Line'. Or a bit under 25%. Most of those were the B divsions made up of the older reservists and less well equipped. None of the armored or motorized infantry divsions were in the main fortified zone of the Third Army.

 

There would have been a lot less panic if the Germans had manuvered as the French expected. The earlier German plans placed first one armored corps of two tank divsions in Army Group A in the Ardennes. Later in December that was increased to three, then to four tank divsions. Finally after the Sickle Cut plan was adopted seven tank divsions and three of the four motorized infantry divsions were moved to the Ardennes sector.

Theses something about having 1,700 tanks show up at a unexpected location that causes bad decisions to be made.

 

According to John Delaney in his Blitzkrieg Campaignes,French third and second army group had in sector from Montmedy on Luxembourg border to Swiss border in the south 14 and 35 divisions deployed respectively.You are right ,they didn't have armour and were class B reserveists.But they could still contribute,just like wast masses of untrained infantry slowed German advance in Barbarossa..
And yeah,panic would be much smaller if original plan went into action.Isn't it fascinating how a few details could turn this campaign in to another direction.Few people give much attention to fall of France,because,it's a foregone conclusion,totally uninteresting campaign because French didn't stand a chance,Germans were uncomparedly superior etc..And it turns out it wasn't necessarily like that at all.

 

All those infantry divsions were sent to the battle front during May and early June. First those designated for the Stratigic Reserve, they formed the Somme-Oise line. Then the others as it became evident the Germans were still able to mount a second offensive. By mid June the fortified zone had been entirely stripped of field units. Only the fortrress garrison remained. Those had to organized ad hoc field units to fill in for the missing infantry divsions for patroling and local counter attacks.

 

Yes I know what you mean about a few details throwing the campign off the historical path. The guy who edsigned the game 'Campaign in the West' published it with several scenarios. The historical scenario he described as a "wind up toy". Wind it up and watch it run out on its own. He had to insert special rules in that scenario to make if play out as if the original French decisions were being made. Allow the French player to make a few diffferent decisions and the German player has a rougher time of it.