Operation FORTITUDE (D-Day Deception)

[Tidewater]

Everybody who knows about D-Day knows about the Allied deception operation which led the Germans to believe the real invasion would come in the Pas de Calais region. I have always wondered just how successful FORTITUDE was. Some German units did move to Normandy after D-Day. How do you measure the success of the operation like FORTITUDE? No enemy units move? Fewer than otherwise? Delayed unit movement? How much delay?

Craig Bickell wrote a good article called, "Operation FORTITUDE SOUTH: An Analysis of its Influence upon German Dispositions and Conduct of Operations in 1944."
He punctures some myths and places things in context.
There were three deception operations: Fortitude North (fake invasion of Norway), Fortitude South (before D-Day trying to keep units away from Normandy) and Fortitude South 2 (after D-Day, to convince the Germans that Normandy was just a diversionary attack and the real invasion would come in Pas de Calais).

Fortitude South had some success, but also some significant failures. In May, Rommel moved the 21st Panzer Division from Rennes (Brittany) to Caen, right behind the British beaches. The Panzer Lehr Division to le Mans and the 91st Luftlande (Airlanding) Division to Cotentin. Rommel believed the invasion would come at Normandy. Despite Fortitude, he moved these powerful units to Normandy.

On June 5, Gerd von Rundstedt (OB West) said, "an attack from Dover against Calais would be ... shortest sea route to the Continent. ... V-I and V-2 sites were located in this area. ... the shortest route to the Ruhr and the heart of industrial Germany ... [it would] sever the forces in Northern France from those along the Mediterranean coast ... if I was Montgomery I would attack the Pas de Calais."

Allied air forces attacked Seine bridges, which isolated Normandy, but to the Germans this also looked like isolating Pas de Calais from reinforcement west of the Seine.

The bottom line, Fortitude South was a mixed bag. Fortitude South 2 was a little more successful.

Bickell writes, "up until the end of June FORTITUDE SOUTH convinced the Germans that Normandy was a subsidiary, although major, landing. ... By August the probability of a second landing had been set aside" and the Germans started acting on that.

In the meantime, few German infantry divisions were moved from Pas de Calais to Normandy and two armored units, 1st SS Panzer and 116th Panzer remained in the Pas de Calais region. Hitler had released 1st SS Panzer on June 8, but (and this is amazing) the Brits got one of there double agents (Brutus) to send a message that night that Patton had said: "now that the diversion in Normandy is going so well, the time had come to commence operations around Calais." Hitler on June 10th rescinded the release of 1st SS Panzer. It was not released until 17 June and did not show up in Normandy until 25 June. The 116th Panzer was not released until 18 July because of the threat at Pas de Calais.

Anyway, interesting article.

 

[Tidewater]

Here is a map showing German unit locations.

The Panzer divisions are highlighted in red.

 

[4Q Basket Case]

There was a fascinating treatment on The Military Channel about the famous operation whereby a body with plans for the invasion at Pas de Calais washed up on the coast of Spain. Essentially, the body that was initially to be used got a bit old, and couldn't be preserved without leaving clear evidence, and spoiling the ruse.

So the officer in charge drove from London to Scotland (several hundred miles) under cover of darkness with no headlights due to blackout rules. There, he recovered the body of a sailor who had recently drowned in salt water when a light aircraft carrier exploded within sight of land. The cause of that explosion is still a matter of debate.

That newer body was loaded onto a submarine and eventually became the one that washed ashore in Spain.

 

[Tidewater]

There was a fascinating treatment on The Military Channel about the famous operation whereby a body with plans for the invasion at Pas de Calais washed up on the coast of Spain. Essentially, the body that was initially to be used got a bit old, and couldn't be preserved without leaving clear evidence, and spoiling the ruse.

So the officer in charge drove from London to Scotland (several hundred miles) under cover of darkness with no headlights due to blackout rules. There, he recovered the body of a sailor who had recently drowned in salt water when a light aircraft carrier exploded within sight of land. The cause of that explosion is still a matter of debate.

That newer body was loaded onto a submarine and eventually became the one that washed ashore in Spain.

That is going to extreme lengths. The Brits are pretty good at the intel side of things. Every one of the secret agents the Jerries dropped into Britain got rolled up and several of them turned into double agents.

In fact, the deception message designed to keep the 1st SS Panzer Division in Belgium was sent by one of the double agents.

 

[Tidewater]

Here is another factor I found interesting.
Operation Fortitude required that the Germans grossly overestimate how many Allied divisions were in Britain because, how could they land all these forces in Normandy and still have enough to land in Pas de Calais?

Over the course of the first half of 1944, Hitler kept poaching German units from the West to send them to Russia, where the need was greater. The Sicherheitsdienst would justify this by under-reporting how many Allied divisions there were in Britain.
So, the the OKW intel guys started doubling the number of Allied divisions in Britain, knowing the SD would halve that number before reporting to Hitler.

Enter Fortitude. Patton was publicly named the commander of the First US Army group (a fictitious unit with lots of fictitious divisions) when the German intel guys were actively looking for lots of fictitious units. I do not even know if the Allies knew about the drama inside German intel, but Fortitude fed the Germans exactly what the Germans were looking for.

 

[TIDE-HSV]

Here is another factor I found interesting.
Operation Fortitude required that the Germans grossly overestimate how many Allied divisions were in Britain because, how could they land all these forces in Normandy and still have enough to land in Pas de Calais?

Over the course of the first half of 1944, Hitler kept poaching German units from the West to send them to Russia, where the need was greater. The Sicherheitsdienst would justify this by under-reporting how many Allied divisions there were in Britain.
So, the the OKW intel guys started doubling the number of Allied divisions in Britain, knowing the SD would halve that number before reporting to Hitler.

Enter Fortitude. Patton was publicly named the commander of the First US Army group (a fictitious unit with lots of fictitious divisions) when the German intel guys were actively looking for lots of fictitious units. I do not even know if the Allies knew about the drama inside German intel, but Fortitude fed the Germans exactly what the Germans were looking for.

We had long since cracked Enigma by then, so I suspect the Allies knew exactly what was going on. Also, the French Underground had lots of eyeballs in Normandy and the area by then, in spite of the damage done by the Abwehr and SS...

 

[crimsonaudio]

fed the Germans exactly what the Germans were looking for.

That's the best kind of propaganda.

 

[Tidewater]

We had long since cracked Enigma by then, so I suspect the Allies knew exactly what was going on. Also, the French Underground had lots of eyeballs in Normandy and the area by then, in spite of the damage done by the Abwehr and SS...

Agreed. I just think it is funny that Hitler would make spur of the moment decisions based on biased info, so one faction of the staff (the pro-OB West faction) "massaged" the intel knowing the other (OKH pro-East) section would massage them back.
And it played right into the Allies' Fortitude deception plan.

The lesson learned is that executives must learn not to finagle the intel. Order the intel folks to tell it exactly as they see it, so sound decisions can be made. (Bush in Iraq, Putin in Ukraine, etc.)

 

[TIDE-HSV]

Agreed. I just think it is funny that Hitler would make spur of the moment decisions based on biased info, so one faction of the staff (the pro-OB West faction) "massaged" the intel knowing the other (OKH pro-East) section would massage them back.
And it played right into the Allies' Fortitude deception plan.

The lesson learned is that executives must learn not to finagle the intel. Order the intel folks to tell it exactly as they see it, so sound decisions can be made. (Bush in Iraq, Putin in Ukraine, etc.)

That, as you posted earlier, the Brits were damned good at sniffing out spies, so England was opaque to Hitler...