I'll let others debate parity of forces at Salerno, and I'd also prefer to keep nukes and chemical weapons out of the mix to stay on topic. As I'm sure you'd agree, nukes would have strategic implications that go far beyond a mere tactical bonus for the allies during a landing.T. A. Gardner wrote:It is. Salerno is the closest that the Germans come to parity with everything but naval forces. They had at least parity in the air and maybe marginal superiority. On land they had a panzer division on the beach when the Allies landed. The landing was 3 infantry divisions (36th US, 46, 56th British). Within a day they reinforced with a second panzergrenadier division and soon had stacked up against the Allies 6 panzer and panzergrenadier (if you count 1st Fallschirmjäger as a pzgr division which it really is in strength) divisions. Yet, every time they massed for an assault the naval forces off shore pummeled the Germans.
Air power couldn't drive the naval forces away even though they smashed several heavy ships pretty good. So long as the Allies had a fleet supporting their troops ashore the Germans couldn't mass and attack successfully. Naval firepower was too strong.
The Allies have the advantage of where to strike. They will know where the Germans have their strength. With the sort of logistics and engineering support the Allies have give them a few days and they have a port on the beachhead, airfields ashore, and are pouring in reinforcements faster than the Germans can even imagine.
Ohama wasn't even that close run. For the US it was more casualties than expected but hardly the massive ones necessary for the beachhead to collapse.
Powerful beach defenses didn't stop the USMC in the Pacific either. Instead, the US simply made sure to pound them into rubble first. Same here. If you push into 1945 the US uses nukes on the beachhead. That pretty much finishes the defenses. And, yes, the US would have landed troops and marched them straight across the smoldering crater too.
I really don't see how Salerno affects my argument. There the emphasis was on a counterattack once the allies were ashore, not a concerted defense action on the beaches themselves. The latter strategy is the one I think gives the Germans the best chance for victory. For the record, I agree that once the allies were a few km inland, it would be very hard for the Germans to push them back.
Concerning allied choice of landing, while it is true that there were huge stretches of coast the allies could land on, both the allies and the Germans knew that only some of that coastline was a viable option for an allied landing. Norway could be abandoned without any major loss, and landings south of Brest would lack the fighter bomber support so vital to allied success in Normandy. Same goes for landings in southern France. That's why the Germans concentrated their mobile panzer units where they did.
Now consider the balance of strength. With no Eastern front to suck men and resources away, it is reasonable to assume the Germans would have been able to concentrate more men on the wall and bring in more heavy guns and bunkers to defend it. More importantly though, by mid-44 the Germans had over 30 Panzer divisions. And only 6 of these were in Northern France for the real D-Day. If there is no eastern front, the Germans could have concentrated 3-4 times as many panzer divisions in the same area. With this much strength in place, I think they could deploy their panzers in a way that any section of beach could be reinforced by at least two panzer divisions within a few hours. Coupled with the fact that if the Germans detected the Allied fleet early (as they did at Dieppe but not so in Normandy), they might even be able to have a panzer division already on the beach the allies were planning to storm before the first landing craft hit the shore.
From what I understand, Omaha was more close than you make it out to be. When reading Zaloga's excellent book, if I remember correctly (I might be mistaken) the Germans had about 1,000 men in the beach defenses against two full American divisions. One of the most important reasons why they lost was because they didn't have enough men to cover the cliffs in-between the exits, which the Americans were eventually able to infiltrate. But since the Germans would have far more men available to cover the beaches without any Eastern front, they would have more men per km of front and more reserves to plug in the gaps.
And the comparison with the Pacific has problems of its own. There, every Japanese garrison was cut off from supply and reinforcement. The allies could bombard the beaches for as long as they liked, at Iwo Jima, the bombardment lasted weeks! But any bombardment in France would have to be far shorter, the penalty being more men and tanks to face the men as they landed. And the interdiction of supply routes also does not pose problems for my defensive proposal. All the Germans needed would be enough local supply to last them 1-2 days of heavy fighting, by which time all Allied chances of success would be gone.
A big problem of amphibious landings is that it is very hard to land AT weapons on the beaches and be able to use them effectively in an area without cover. If the Germans were able to get strong armour units in an area where the allies had not yet made it off the beaches, the allied troops would be slaughtered.