What would it take to make a Secure Atlantic Wall?

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pintere
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Re: What would it take to make a Secure Atlantic Wall?

#91

Post by pintere » 22 Mar 2015, 00:42

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'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.

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.

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Re: What would it take to make a Secure Atlantic Wall?

#92

Post by magicdragon » 22 Mar 2015, 02:59

T. A. Gardner wrote:
Salerno is this scenario.
Err no its not, we are taking about a Normandy type landing, against 100+ divisions who had spent 2 years preparing for an attack
The Allies, and the US in particular could and did park a fleet off an enemy coast indefinitely. Okinawa is the best and largest example. Sure, individual ships came and went but the fleet itself stayed put. They did it off Anzio. They did it at Sicily and at Salerno.
A fleet but not the same fleet strength you had on D Day +1, and not trying to overcome the intrinsic difficulties of providing close direct fire support in the middle of a European of winter. If the Germans had got lucky and taken out a couple of battleships the navy would have been mighty reluctant to keep them in such a role.
There are literally hundreds of beaches that are suitable for landings from Norway to Greece. The Germans have to defend it all. They don't have the resources to put in even the necessary shore batteries of heavy guns that could really take on a fleet off shore. The number of guns of 25 to 40 cm (10" to 16") that they put in place was miniscule. A handful in Norway, another handful at Pas de Calais, and a few in the Channel Islands. Add a few more existing French guns and that's the extent of weapons really capable of taking on ships. Stuff 10 to 15cm is barely going to be able to take on light naval vessels. Add that the Germans didn't develop really good coast defense fire controls either and you have a real problem.
“Hundreds of beaches that are suitable for landings from Norway to Greece” really? For landing an army sized force, with the right tides, consistency of surface, with scaleable sea cliffs, without dominating natural features or defenses, or within the range of effective fighter cover? If you are not fighting in Russia you do not need the siege artillery deposited around Leningrad for 2 years or the coastal artillery placed in the Baltic. Nor have you lost the staggering numbers of artillery left behind in the German retreats in 1942-44 (particularly damaging on you artillery park of super-heavy artillery abandoned in these reverses) You have also have access to the Corps level super-heavy artillery assets (21cm K 39 and 21cm Mrs 18) available to a German Field Army twice the size (and up to full strength) than it was historically in Normandy 1944. As the chances are that the Med is an Axis lake post 1942, so no artillery lost at Tunisgrad, Sicily and no requirement to build, equip and man the Gustav Line, the Gothic line or other major defensive positions on the Italian mainland, Greece or the Balkans. While you are at it why not strip the guns from those redundant Italian coastal defences plus any Italian cruisers, battleships or destroyers under long-term repair or half-built (to help pay for all those second hand Pz IV’s you have sold to equip the 3 Italian armoured divisions now available with all those Italian Alpini divisions to help garrison Norway so allowing the Germans to release more troops to bolster defences in the Low countries and France)?
And the Allies didn't spend months prior to D-Day wrecking the French rail system, methodically wiping out radar stations, bombing ports into rubble, and such? Yes, they did. They also did it in such a way as to make it hard for the Germans to predict where the assault would land. Of course, taking out the tactical beach defenses required less pummeling than a tiny island that is heavily defended because in most cases the defenses of the Atlantic Wall were far less concentrated. But, as carpet bombing in Normandy proved, the Allies could deliver a massive blow using air power that would wipe out tactical defenses just as that did to Panzer Lehr for example.
The point is that German reinforcements still got there regardless of the impressive efforts of 2nd TAF and others even if more slowly and despite significant casualties (men and equipment) in transit. I would be interested to see how many tanks or artillery the Japanese landed on Okinawa after the first US landings? You would need to inflict a Panzer Lehr type bombing attack every day for a month to seriously degrade a 100+ division army and bring it down to its knees (plus the inevitable accidents which take out a couple of your own divisions in the process). Besides which Panzer Lehr and other panzer divisions were in the front-line (more targetable) positions because the Germans did have to put them there simply to hold the line, with an extra 50 (mostly infantry) divisions (supported by 1000+ Stug IIIs) you slap the infantry divisions in the frontline and leaving the panzers to counter attack any breakthrough – historically in 1944 the Germans did not have the luxury to do both. The key issue with many of the Pacific island assaults apart from obvious exceptions like Guadalcanal is that once the USMC and army troops landed the defenders could expect no reinforcement or supply by definition they would get weaker day-by-day relative to the US forces. This would not be true of an invasion in 1944 where 2/3 of the entire German Field Amy is deployed in the West and their logistics apparatus still worked even if significantly degraded.


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Re: What would it take to make a Secure Atlantic Wall?

#93

Post by glenn239 » 24 Mar 2015, 18:56

There are literally hundreds of beaches that are suitable for landings from Norway to Greece. The Germans have to defend it all
No, they'd only have to defend beaches that lead somewhere militarily significant, like a communications hub or a potential airfield complex.

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Re: What would it take to make a Secure Atlantic Wall?

#94

Post by Sheldrake » 24 Mar 2015, 22:17

glenn239 wrote:
There are literally hundreds of beaches that are suitable for landings from Norway to Greece. The Germans have to defend it all
No, they'd only have to defend beaches that lead somewhere militarily significant, like a communications hub or a potential airfield complex.
Hmmm that is the kind of thinking the Germans adopted and the key conclusion was that the beach needed to lead to a good sized port. It is one reason why the defences on the actual invasion coast from the Vire to the Orne was only 2/3 as strong as the defences of the Eastern Cotentin peninsular and a fraction of the strenght of the defences of the ports themselves.

Mulberry Harebour meant that the allies did not need ports, airfield construction engineers meant that airfields were not important in themselves.

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Re: What would it take to make a Secure Atlantic Wall?

#95

Post by BDV » 24 Mar 2015, 22:36

AngloAmericans can also use an invasion to force Luftwaffe to come out and play.
Nobody expects the Fallschirm! Our chief weapon is surprise; surprise and fear; fear and surprise. Our 2 weapons are fear and surprise; and ruthless efficiency. Our *3* weapons are fear, surprise, and ruthless efficiency; and almost fanatical devotion

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Re: What would it take to make a Secure Atlantic Wall?

#96

Post by Gooner1 » 25 Mar 2015, 11:50

If the Germans had of defeated the Soviet Union and had x hundreds of divisions to defend Festung Europa the Allies would have probably just done something sneaky - like invading Spain! :D

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Re: What would it take to make a Secure Atlantic Wall?

#97

Post by JAG13 » 28 Mar 2015, 01:40

So once the troops are ashore its game over?

...someone please travel back in time and tell the guys at Anzio, Gallipolli, Salonica, Wake...

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Re: What would it take to make a Secure Atlantic Wall?

#98

Post by T. A. Gardner » 28 Mar 2015, 05:58

JAG13 wrote:So once the troops are ashore its game over?

...someone please travel back in time and tell the guys at Anzio, Gallipolli, Salonica, Wake...

Except at Anzio there was no opposition to the landing. The Allies chose to sit on the beach rather than advance inland.

At Wake the first Japanese landing was defeated at sea by coast defense guns and aircraft, a rarity. That was due mainly to the Japanese sending what amounted to an ineffective landing force to begin with. Their second landing succeeded with heavy casualties. You might note that the Midway invasion was defeated at sea also.

At Gallipoli the Allied forces made it ashore. That they could not overcome the defenses in the end is due mainly to the nature of WW 1 combat. Neither side could really budge the other.

At Crete the German attempt to invade by sea was defeated at sea.

Like I stated: The surest way to defeat an amphibious assault is to stop it at sea. Once the troops get on the beach it is overwhelming odds they will get to stay there and that the defenders won't push them back into the sea. So, yes, once the troops are ashore it's "game over" as far as the landings go.

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Re: What would it take to make a Secure Atlantic Wall?

#99

Post by Carl Schwamberger » 29 Mar 2015, 01:59

T. A. Gardner wrote:...

At Wake the first Japanese landing was defeated at sea by coast defense guns and aircraft, a rarity. That was due mainly to the Japanese sending what amounted to an ineffective landing force to begin with. Their second landing succeeded with heavy casualties. You might note that the Midway invasion was defeated at sea also.

...

At Crete the German attempt to invade by sea was defeated at sea.

Like I stated: The surest way to defeat an amphibious assault is to stop it at sea. Once the troops get on the beach it is overwhelming odds they will get to stay there and that the defenders won't push them back into the sea. So, yes, once the troops are ashore it's "game over" as far as the landings go.
You could add Operation Reservist to the list. Both destroyers were shot to ribbons & the landing force massacred before the ships reached the target docks.

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Re: What would it take to make a Secure Atlantic Wall?

#100

Post by Carl Schwamberger » 29 Mar 2015, 02:24

BDV wrote:AngloAmericans can also use an invasion to force Luftwaffe to come out and play.
Which among other things leads back around to the ability to interdict the German transport system. OTL the 7th & 15th Armies fighting in Normandy saw their ammunition, fuel, manpower, & other reserves dwindle to nothing. Then the units shrank until ineffective. They were unable to match losses with replacements that had to be shuffled slowly forward at night.

The proposition that Allied air power did not prevent any reinforcing units from reaching the battle front in Normandy is a bit of a distortion. First: Eisenhower only asked they be delayed two weeks, and that refered to only the reserves present in the 15th Armys sector, north of the Seine.

Second: The reinforcement were reduced to scampering along in the brief summer nights. The early attempts to travel in daylight on 6th, 7th, 8th June were hammered by constant air attack, spending more time seeking concealment and cover than moving on the roads, and losing numerous vehicles with their material cargo.

Add in hundreds or even fifty mobile and immobile divisions & the defenders supply requirement increases proportionatly, but the capacity of the Franco Belgian railroads is finite, and reduced no less by Allied air attacks. What use is there in adding 50% more men to the Atlantic Wall when the ability to supply the original number was falling below the necessary level?

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Re: What would it take to make a Secure Atlantic Wall?

#101

Post by BDV » 29 Mar 2015, 21:23

I am sorry to return to my favourite idee fixe, but to collapse the Soviets, it means that Germany has dedicated everything, I mean everything to the defeat of Soviet Union, and that as early as Summer 1940.

That means that say in mid-1942, when finally the Reich reorients its forces west, the material state of the western defenses is about 18 months behind the historical schedule, the UBoats remain a minimal nuisance, and the air attacks on Britain have been below modest.
Nobody expects the Fallschirm! Our chief weapon is surprise; surprise and fear; fear and surprise. Our 2 weapons are fear and surprise; and ruthless efficiency. Our *3* weapons are fear, surprise, and ruthless efficiency; and almost fanatical devotion

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Re: What would it take to make a Secure Atlantic Wall?

#102

Post by GoldenState » 09 May 2015, 13:52

I wonder, there should have been a lot of 75mm guns of the Krupp 1903 type or equivalents in German inventory (over 1,000 from the 1943 takeover of Italy I would think). Could these have been set up for direct fire against landing craft?

If effective, one would think that a well placed couple thousand of those should have made a noticeable impact on D Day.

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Re: What would it take to make a Secure Atlantic Wall?

#103

Post by Carl Schwamberger » 12 May 2015, 04:44

GoldenState wrote:... a lot of 75mm guns ... (over 1,000 from the 1943 takeover of Italy I would think). ... set up for direct fire against landing craft? ...
More is always better. there is the problem of dimimishing returns. Protecting 1000 additional cannon with a proportionate increase in concrete, steel, comm equipment, and labor pushes towards limits in what is possible there. Perhaps the extra guns will mean part or all are less well protected, higher losses in preparation attacks.

I wonder how the actual density is increased? Omaha Beach had four 5 cm, seven 7.5 cm & one 8.8 cm cannon positioned for direct fire in concrete bunkers. If hypothetically 1000 guns averages out to one per two kilometer of beach (?) then that adds four more to Omaha Beach. One per kilometer raises the total to 20 guns on Omaha beach. That adds at least another 20 - 25 % to the construction task for bunkers, comm, ect...

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