What if the Nazis had expected something to happen on June 6, 1944?

[NoPref]

June 6, 1944

The Allies launch the D-Day invasion as actually happened, but the Germans have anticipated that an invasion was likely on this date. They don't know where, or exactly when. No major commanders (e.g. Rommel) go on leave. They don't stand-to, but the local commanders are all warned that for June 4-7 there is a higher probability of an Allied invasion. Not a guarantee, not a known fact. Mostly an intelligence estimate that June 4-7 is a potential invasion time.

Would this have made any difference? If so, what?

[T. A. Gardner]

No. The Germans brought old men, kids, and crap to a major @$$ kicking by professional @$$ kickers. They were going to lose by just showing up.

[Capt AFB]

It depends if someone decides to wake up the Fuhrer so he can authorize the release the panzer divisions held in reserve.

Rommel being away is a non-issue at the beginning of D-Day. His Chief of Staff, Speidel, was highly capable and had the authority to deploy and move troops around to counter the Allied landings.

What would had probably made a difference is German intelligence confirming that the landing in Normandy was the main event and not a diversion for a landing at the Pas-de-Calais.

[T. A. Gardner]

Originally Posted by Capt AFB

It depends if someone decides to wake up the Fuhrer so he can authorize the release the panzer divisions held in reserve.

Makes no difference. Operations Taxable and Glimmer are going on and the German command at Calais is reporting a large invasion fleet approaching. Yes, they were doing that and they had no way of verifying its presence out to sea.

https://en.wikipedia.org/wiki/D-Day_...er_and_Taxable

That would delay their release for about a day.

Then there's the problem of them moving to Normandy. Between the air attacks, the lack of rail bridges (in particular) it was nearly a week to get the panzers there, even as the motor elements and infantry arrived within 72 hours. By then it was too late.

The Germans expected the invasion at Calais, and the Allies made sure to give them one, at least on radar...

[Pruitt]

The Germans could also have moved several high quality divisions from South France to the Paris area. There was several SS Panzer Divisions (LAH, DR being rebuilt, 12th HJ being fitted out) and a Panzer Grenadier Division (17th Reichsfuhrer SS? just being fitted out).

Moving some of the divisions they would move North later on would have saved some time.

I can't say if enough could have been brought to bear to defeat the landings but at least one beach had serious difficulties after the Germans put elements of a first class Infantry Division there for war games.

Pruitt

[Pruitt]

Originally Posted by T. A. Gardner

Then there's the problem of them moving to Normandy. Between the air attacks, the lack of rail bridges (in particular) it was nearly a week to get the panzers there, even as the motor elements and infantry arrived within 72 hours. By then it was too late.

The Germans expected the invasion at Calais, and the Allies made sure to give them one, at least on radar...

The German 21st Panzer Division had a kampfgruppe penetrate almost to the beach before Naval Gunfire beat them off.

Pruitt

[T. A. Gardner]

Originally Posted by Pruitt

The German 21st Panzer Division had a kampfgruppe penetrate almost to the beach before Naval Gunfire beat them off.

Pruitt

21st Panzer was the only panzer division in Normandy at the time. It was stationed outside Caen. By the by, it also was the first panzer division in Normandy to become combat ineffective.

[Aber]

Originally Posted by Pruitt

The German 21st Panzer Division had a kampfgruppe penetrate almost to the beach before Naval Gunfire beat them off.

Naval gunfire had nothing to do with it, and they didn't penetrate to a landing beach, they got close to the coast between two of the landing beaches.

The kampfgruppe attacking 6th Airborne Division didn't make any significant progress and the one that tried heading towards Sword got stopped dead in its tracks with heavy losses.

[Aber]

Originally Posted by NoPref

June 6, 1944

The Allies launch the D-Day invasion as actually happened, but the Germans have anticipated that an invasion was likely on this date. They don't know where, or exactly when. No major commanders (e.g. Rommel) go on leave. They don't stand-to, but the local commanders are all warned that for June 4-7 there is a higher probability of an Allied invasion. Not a guarantee, not a known fact. Mostly an intelligence estimate that June 4-7 is a potential invasion time.

Would this have made any difference? If so, what?

The actual D-Day plan assumed that the Germans would have spotted the mine-sweeping fleet on the approach, and the defences in Normandy would have been on alert.

As noted earlier the Germans should also have noted a 'fleet' moving towards Calais.

Neither of these are likely to have caused the movement of the Panzer reserve as they would not have been sure which was the real invasion, and the results of the 21st Panzer attacks on D-Day show that they are not likely to have made a huge difference even if they had arrived.

There are not many other changes the Germans could have made, but one would have been moving ammunition reserves forward. This might have increased casualties on Omaha where the troops were trapped on the beach.

[MarkV]

Not only was there a phantom fleet heading for Calais but lots of equally phantom aircraft which were I believe actually a handful of old Defiants fitted with specially adapted airborne radar to emit the signature of large numbers of air craft.

At the same time the double agents of the Double Cross set up were telling German intelligence that anything happening in Normandy was a decoy designed to draw the panzers away from the Pas de Calais. As Hitler's intuition was telling him that the Pas de Calais was the place where an invasion would come this was all swallowed very easily. Hitler had already started to micro manage matters and there would be no way the German army could have made a rapid decision to send the tanks to Normandy tout suit

The long and the short of it was that the Germans did expect something to happen at the beginning of June but they were fooled as to what and where.

[T. A. Gardner]

Originally Posted by MarkV

Not only was there a phantom fleet heading for Calais but lots of equally phantom aircraft which were I believe actually a handful of old Defiants fitted with specially adapted airborne radar to emit the signature of large numbers of air craft.

Actually, it was a couple of squadrons of Stirlings and Lancasters specially fitted to eject massive amounts of chaff and spoofing jammers like Moonshine (makes one plane look like 10). They trained for months to fly a "racetrack" course in precise formation that would give a continuous wall of chaff moving forward at about 6 knots making it look like an invasion fleet was approaching.
The motor launches towing barrage balloons with radar reflectors and more jammers below added to the effect. The planners even expected some gaps in the coverage which was why the boats were added. That way the radar operators would occasionally get a return on a large solid target (like a large warship) through the expected jamming.
The planners had looked at the problem from the German side and set up the deception to give the Germans exactly what they would have expected.

[MarkV]

Originally Posted by T. A. Gardner

Actually, it was a couple of squadrons of Stirlings and Lancasters specially fitted to eject massive amounts of chaff and spoofing jammers like Moonshine (makes one plane look like 10). They trained for months to fly a "racetrack" course in precise formation that would give a continuous wall of chaff moving forward at about 6 knots making it look like an invasion fleet was approaching.

No that is not what i was talking about -although it did happen. Back in 1942 Defiant IIs were specially fitted out to be be decoys to cover the first USAAF raids on the Continent. They were chosen because :-

• As early night fighters they were kitted out with radar and it was a case of swapping over black boxes rather than starting from scratch
• With their four gun turret it was considered that they could defend themselves over France if necessary.

So successful were they at spoofing German radar stations into thinking they were a bomber stream that it was decided that before the Germans realised what was going on they should be held back for when they would be more useful to cover an invasion. I found out about them when doing some research for a modeling competition for aircraft with invasion stripes and thought that Defiants with stripes would be "cool". However the technology was not only invaluable in WW2 it was also so postwar in the embryonic cold war and it was impossible to find any records that said much more than yes they did exist.

[T. A. Gardner]

Originally Posted by MarkV

No that is not what i was talking about -although it did happen. Back in 1942 Defiant IIs were specially fitted out to be be decoys to cover the first USAAF raids on the Continent. They were chosen because :-

• As early night fighters they were kitted out with radar and it was a case of swapping over black boxes rather than starting from scratch
• With their four gun turret it was considered that they could defend themselves over France if necessary.

So successful were they at spoofing German radar stations into thinking they were a bomber stream that it was decided that before the Germans realised what was going on they should be held back for when they would be more useful to cover an invasion. I found out about them when doing some research for a modeling competition for aircraft with invasion stripes and thought that Defiants with stripes would be "cool". However the technology was not only invaluable in WW2 it was also so postwar in the embryonic cold war and it was impossible to find any records that said much more than yes they did exist.

The early days of jamming were mostly for the RAF. The Defiant only stayed in service as a jammer for a relatively short period of time as it had neither the room or electrical power to handle the more powerful ones.
Early jamming was mostly with Moonshine, a deception repeater, that proved marginal at best. Making a raid look bigger than it was didn't provide much deception.

With the advent of Mandrel, you needed bigger, higher flying, aircraft to handle it. These put up a "screen" that allowed the bombers to form and head to the continent behind a fairly complete wall of jamming.
Postwar it was found that Mandrel didn't work the way it was advertised. Instead, the Germans accepted they were being jammed this way and that it meant a big raid or raids was assembling. They usually got enough burn-through early enough that they could plot the raid's likely course and even guess the target.

The Defiant as a ECM aircraft only lasted into early 1942.

[MarkV]

Originally Posted by T. A. Gardner

The early days of jamming were mostly for the RAF. The Defiant only stayed in service as a jammer for a relatively short period of time as it had neither the room or electrical power to handle the more powerful ones.
.

515 squadron was formed in April 1942 and used Moonshine Defiants not not as a jamming device but to amplify Freya signals creating the impression of a large formation where there was none. In this they were very successful sometimes attracting up to 300 fighters to empty skies. However as the RAF were using dispersed bomber streams they were best suited to acting as decoys for the more tightly formated USAAF daylight raids. By the time that the Germans detected the real raid many fighters were out of position and needing to land and refuel. As more and more Freya were built and there were not enough Moonlight Defiants to cover them it became apparent that it would become ever more difficult to fool the German defensive system. It was decided therefore to withdraw the Defiants before German intelligence discovered what they were up to and retain them in order to carry out a surprise decoy in a very particular and concentrated area - to wit the invasion. By the beginning of 1943 515 had re-equipped with other types and Mandrel and the Moonlight Defiants were retained and intended for invasion duties. For very obvious reasons their existence was kept very secret which is why it has proved very difficult to learn more about them.

[Carl Schwamberg]

Originally Posted by T. A. Gardner

Makes no difference. Operations Taxable and Glimmer are going on and the German command at Calais is reporting a large invasion fleet approaching. Yes, they were doing that and they had no way of verifying its presence out to sea.

https://en.wikipedia.org/wiki/D-Day_...er_and_Taxable

...
The Germans expected the invasion at Calais, and the Allies made sure to give them one, at least on radar...

Holts 'The Decivers' has a description of this.