You have to remember that Hitlers response to an Allied invasion of Denmark would probaply been rapid as opposed to the landings in Normandy. Remembering his fascination with Norway and Swedish iron ore...furthermore logistics for Germans would have been MUCH easier than in France.
Considering the man wasn't convinced that Normandy landings were the real thing until some time had passed, an invasion of Denmark would have been much more surprising... Then issue on how Germans could react should be considered. If invasion targets are Sjaelland, Jutland north of Limfjord and some adjacent islands the question is how could Germans make an impact on invasion zones? Opposed crossing over Limfjord or Great Belt would need time to prepare, during which additional Allied forces in addition to initial forces could be poured in and various light and heavy naval forces could be transferred to the theater. In France, although forces were under heavy air attack, they could move during long nights without problems of trans-shipment.
Additionally, no amount of ground forces based in Norway would have an impact on Denmark. The air forces in Norway were fairly weak, and reinforcing them would be tricky as reinforcements could be flown in first to Finland, then to Northern Norway and only then to Southern Norway.
The main advantage being, of course, that it's a scenario which has not been discussed very often.
The advantage over Overlord would be more efficient use of ample naval power available to allies, avoiding the logistical problems of supplying advancing armies from France to Germany, bonus use of tactical airpower, greater effect on morale, and finally, a lodgement more to east than OTL, causing Stalin to get less of Eastern Europe.
They don't directly need to attack the invasion beaches, just isolate the area. Invading Sjaelland would probaply only be a waste of resrouces for Allies, as the Axis simply need to take(or keep) Jutland and the allied forces in Sjaelland will eventually starve to death.
As long as the Germans keep the Allies from breaking out of Denmark they hold the cards, as they can reinforce faster than Allies.
Norway is of no importance, Germany is. Even Hitler would not allow a landing so close to Germany, and would probaply order any and all available forces(including the airforce which is well within range) to drive back the attacker.
The main advantage being, of course, that it's a scenario which has not been discussed very often.
The advantage over Overlord would be more efficient use of ample naval power available to allies, avoiding the logistical problems of supplying advancing armies from France to Germany, bonus use of tactical airpower, greater effect on morale, and finally, a lodgement more to east than OTL, causing Stalin to get less of Eastern Europe.
As to making more use of the superior naval power, that's a consideration regarding the means, not really an advantage over Overlord. It is worth using it only if there are objectives I cannot achieve without it; otherwise, it's not really an advantage for me.
Tactical air power? Well, and isn't it better when the distance between their airstrips and the battlefield is shorter?
As to avoiding the logistical work of going through France, for a long time after the landing, certainly that could be avoided. OTOH, I'd have a much harder logistical work up front, during and immediately after the landing, given the much higher logistical strain when compared to Normandy.
No argument about the Soviets advancing less into Europe. One wonders whether that wouldn't be a reason _against_ the scheme, in the Allied decision-makers' minds.
Well, in my concept Allies would not invade entire Jutland, just the north portion of it. As for the rest, how can a German occupation of Jutland threaten Sjaelland and Lolland? Only way to interdict Allied supplies would be via air power or sea power, in both of which Germany was deficient. Coastal artillery lacks range. In top of it, checking from the map, Sjaelland looks like it's filled with protected natural harbours, something which Normandy lacked. Plus no tides and not as much storms. Thus the ability to scrap such concepts as Mulberry.
Of course going down from Jutland may or may not work well. Supplying large scale operations from it's harbors might prove to be difficult. It would also present Germans a single front to defend. One factor in support for it would be ability to use very powerful naval gunfire support. Follow-up landing from Sjaelland-Lolland might work better, as it would multiply the amount of terrain Germany would have to defend against.
Yes, but Luftwaffe would have been no match to airpower Allies would have been able to project to Denmark.
The danger of the landing force being cut off and destroyed in detail is extreme. In the case of D-Day the Allies were able to push 130,000 troops onto the Beach in the first 24 hours. Given the distances involved there is no way to put that many troops over the beach. The Heer will be operating along interior lines, allowing them to rapidly move forces to the invasion points, including moving troops from the Strategic reserve via the still undamaged rail system (unlike the system in France that had been extensively prepped by TACair, the German system was outside the range of fighter-bombers).
You have greatly underestimated the danger from enemy submarines. The Baltic is almost an ideal hunting ground for subs due to the very poor sonar conditions, short range from base for the U-boats and restricted waters involved as well as the still potent surface threat posed by the small surface combatants that the Kreigsmarine operated in the Baltic (LSTs, in particular, were remarkably vulnerable to torpedo attack, as were other Amphibious vessels). While the German forces would unquestionably have suffered appalling losses attacking the amphibious/troop convoy the losses to allied troops, especially the assault troops would have been equally devestating.
All this risk is in order to end the war, at best, five months earlier. This is even less useful than it appears since it will add several months to the Pacific War (or at the minimum, result in the deaths of thousands more Allied POWs in Japanese hands).
So do tell me, what would be the point of only taking northern parts of Jutland? What kind of war winning move is that supposed to be?
Regarding ports, you need big ports not some natural harbours or small town docks.
Now if Allies would land in Denmark moving that thousand tanks plus replacements there would be much easier and
would probaply have been done.