"Blitzkreig" wasn't the important bit. The important bit was "throw Rundstedt at the problem".

It doesn't matter what "idea" you gave Rundstedt, he will get the job done. He's the brilliant mind that allowed Poland, Belgium, France, and the southern-push of Soviet Union to be taken so quickly.

Rundstedt lost his position as Field Marshal because he began advocating for peace after the Allied landings (Famously quoted as: "Make peace you fools! What else can you do?"). Still, he was reinstated in time for the Battle of the Bulge, and boy-oh-boy, was that a surprise to the Allies.

I mean, Rundstedt couldn't squeeze a strategic victory from that hopeless situation of 1944/1945 (and was long an advocate of peace before then). But the fact that he grabbed a temporary tactical victory in those conditions just proves how incredible he was as a commander (well, that... and everything else he did in WW2).

------

Blitzkreig, as a strategy, is largely "Lets drive really fast in airplanes, cars and tanks, and communicate by radio to stay coordinated on the front".

It was the obvious strategy given the new technological advancements at the time. It should be compared/contrasted with the French strategy (which was the use of heavier tanks that marched roughly the same speed as infantry... largely because the French haven't adopted the Radio yet)... but the Blitzkreig style had its flaws.

French tanks had bigger guns and heavier armor: the early Panzers were light and fast but utterly outgunned. It almost certainly only worked because of Rundstedt's brilliance. If the French were given an extra few more days to pull their heavy tanks to Sedan (lets say The Battle of Sedan was just a few days later than historical), the French probably could have held off the German assault entirely.

The Meuse is a huge river, it would have been very difficult for the Germans to cross if French heavy-armor was actually guarding that river. Indeed, the Germans were only successful because the bombing campaign vs the bridges of the Meuse were stopped by the Luftwaffe. And also because French troops panicked and retreated off of some misinformation.

-----

That's a lot of details to get right: moving through mountainous + forested region (without roads!!) with speed. Defending key bridges using ground and air forces. A feint attack to the north to draw away French forces from this area. There was also some luck and awful moves by the French commanders in the area.

Then adequately defending against the heavy-French armor counter-attack with only light tanks (tanks with 1/2 the armor and 1/4th the cannon size), to give time for your slower troops to cross the Ardenes and reinforce the position. The German tanks had to draw and trap the French heavy-armor against the larger anti-tank guns.

The "standard" 37mm cannons on the Panzers and of typical infantry were literally bouncing off of French armor, dealing no effective damage. In contrast, the French Char B1, while slow, had a 75 mm gun that obliterated the German armor.

EDIT: The French Char B1, thanks to the "Heavy Armor" style of the French, took on 140 shells from Panzer IV and Panzer III before destroying all 13 tank opponents simultaneously. That's the strength of the French counter-attack at the Battle of Stonne.

Blitzkreig required higher-speed tanks with smaller guns and lesser armor. Really, if there were more B1s defending this area, the Germans would have been screwed.