WI: Manstein replaces Brauchitsch in February 1940

Walther von Brauchitsch was the Commander-in-Chief of the Wehrmacht on the eve of Fall Gelb, the amended invasion plan for France and the Low Countries.
However, though Hitler privately claimed otherwise, the authorship of the final plan can be primarily attributed to one of Brauchitsch's subordinators, the famous Erich von Manstein; an officer who was able to convince Hitler to adopt it in lieu of more conservative battle plans favored by Brauchitsch in early 1940.

So the POD is that upon OTL's meeting with Manstein,Hitler is so impressed with the compatibility of the plan and thus the man's strategic vision with his own ideology, decides to sack Brauchitsch and replace him with Erich.

What effects might we see for the Wehrmacht throughout the rest of the war?
 
Probably an Officers revolt due to placing a relatively junior officer in ...

Plus this...
...
However, though Hitler privately claimed otherwise, the authorship of the final plan can be primarily attributed to one of Brauchitsch's subordinators, the famous Erich von Manstein; an officer who was able to convince Hitler to adopt it in lieu of more conservative battle plans favored by Brauchitsch in early 1940...

...is wholly nonsense. Manstein was not Brauchtischs subordinate, he was chief of staff for Rundsteadt in Army Group A until January 1940, when he was elevated to corps command. As CoS Manstein was ordered to write three operational plans for Army Group A to be tested at a wargame in November 1940. The plans were part of the revamping of offensive plans Chief of Staff Halder had ordered for the entire army. The plans Manstein wrote for Army Group A included only one armored corps, and went only as far as gaining a bridgehead across the Meuse river. A breakout and encirclement maneuver was not part of the plan presented.

The Sicklecut maneuver and required concentration of armored corps in Army Groups A sector in the Ardennes was a long evolved thing through a series of map and field exercises at Halders HQ in Zossen, among AG A and B, and the individual armies. Manstein was a skilled general and army commander, but his claim of authorship of the sickle cut maneuver does not hold up in light of the plans he wrote for AG A in October/November 1939. Guderian also claimed credit, tho his role as the 'genius originator' is equally unsubstantiated. The famous meeting of Manstein & Hitler in January 1940 occurred after Halder had briefed Hitler on the current plan, with a strengthened armored force in the Ardennes, so Hitler was hearing nothing from Manstein he had not already heard at the regular weekly briefings from the CoS.

Halder never claimed much credit for the sickle cut plan. Tho it was his repeated testing of the plans in map games and field exercises from November 1939 through March 1940 that caused it to develop. Rundsteadt had more directly to do with the details of the sickle cut maneuver as it was his Army Group that executed it. & no one remembers who his chief of staff was in those months despite that he did most of the long and late hours rewriting the plans every few weeks after each exercise testing it. Kleist who commanded the combined Panzer Group of three armored corps was also deeply involved in the development of the plan from January.

Mansteins claims seem to derive from a fair bit of post war bragging & possibly a counter to Guderians claims for ownership. They were boosted by sloppy research and fanboys of Manstein who don't feel "capable" and "skilled" are good enough for their hero and make him out to be some sort of god of war. Mays in 'Strange Victory' his analysis of the development of the German victory of 1940 goes into considerable detail on this subject. Its clear this victory was the result of a team of well trained and experienced leaders and staff applying critical thinking and repeated testing to developing a difficult and risky military operation.
 
Possiblly the most important contributor to the sickle cut plan was a Lt Col in the 'Enemies Armis West section of the Army intelligence service. All the plans tested by Halders staff and Army Groups A & B failed to achieve the strategic goals. Most had difficulty reaching the operational goals. this included the material contributed my Manstein for the November 39 map exercise. Tho Halder & the others noted weighting the "schwerpunckt" to AG A in the Ardennes had a better outcome than the other two options tested.

The Lt Col List (name?) argued the French armies were given to high a level of efficiency in the exercises or tests. That the reaction time of the senior French army commanders would be slower than allowed in the exercises, by 24 to 48 hours. Some generals, including Guderian, Kleist, possibly Rundsteadt and Halder considered the possibility & saw how that could grossly effect the outcome. In early March LtCol Lists proposal was applied to the war game & the result was catastrophic for the defense. This gave the key German leaders some confidence the sickle cut maneuver had a chance of working. Others argued it was a unwarranted changing of the rules to get a favorable out come for the attacker. Since by this point it had been demonstrated repeatedly any attack in 1940 was a risky and desperate move Halder & Rundsteadt overrode the others objections and went with the sickle cut maneuver. they agreed the odds were poor, but still better than the other plans tested.
 
Thanks to Carl Schwamberger for his informed responses. This is an example of a POD that is not so much ASB as it is stupid, since there was no reason for any of the main actors concerned to implement the POD.

A few minor points can be added. The first is that Manstein was a Colonel in 1939, and while there are example of the top job in the army being given to relatively junior generals, there is no precedent for it going to someone who was not even a general at the start of the war.

The second is that the German Army in 1939 was not exactly short of talented officers more senior to Manstein who could have done Brauchitsch's job, and this includes Brauchitsch himself.

The third is that normally the "commander in chief" of a national army is the head of state. The post of commander in chief of the German Army being separate from the German head of state was an outcome of Weimer era political maneuvering, and when Hitler did replace Brauchitsch, which he seems to have done mainly because Brauchitsch's health was really bad at the time, he replaced him with himself, which in fact was entirely appropriate.

Now, there was the post of Chief of Staff of the German Army, which in terms of operations was probably more important than the Commander in Chief job anyway, that would have to be held by a general, and in fact in 1942 Hitler appointed a Chief of Staff of an Army Group, Zietzler to the job. Zietzler's successor was Guderian, who had been an Inspector General and an army group, though not an army group commander. Both were more credible candidates for the job at the time of their appointment than Manstein would have been in 1940. However, putting Manstein here is not a stretch, though coming up with a reason for Hitler to replace Halder at that time is a problem.

The fourth point is that the first really serious disagreement between Hitler and OkH was on the importance of taking Moscow early during in the invasion of Russia, otherwise they were on the same page and functionally, Brauchitsch and Halder had wide leeway though they had to deal with Hitler more than the probably would have liked. And when Hitler did start having serious disagreements with his generals on operations, he had no problem with replacing them, even ones he respected. So I don't see what this POD accomplishes.
 
Top