Seelöwe - Diversion Operations by the KM

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Seelöwe - Diversion Operations by the KM

Post by michammer » 27 Apr 2007 01:49

Split from: http://forum.axishistory.com/viewtopic.php?t=119718 by the moderator - Andreas
Tim Smith wrote:
RichTO90 wrote: The simple facts, which you may chose to ignore if you wish, was that the capitol units of the KM only figured in Seelöwe as diversions.
I'm not ignoring or disputing that. Nowhere have I claimed that Hipper and Scheer would be directly escorting the invasion fleet.

I am claiming Hipper and Scheer would be sent out on diversions. A diversion is 'protecting the troops'. Indirectly protecting them.
I wonder about how effective the diversions would be. The only reason to use these ships as a diversion is to pull RN units away from the invasion area. However, would any units actually be pulled away from the Channel? Surely if these KM units were sighted, the RN would send its capital ships to engage them, not the destroyers and cruisers that would be used in the Channel to counter an invasion.

Did the RN actually plan to use the capital ships in the Channel except in an extreme emergency?

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Re: Seelöwe - Diversion Operations by the KM

Post by fredleander » 30 Apr 2007 13:16

michammer wrote:Split from: http://forum.axishistory.com/viewtopic.php?t=119718 by the moderator - Andreas
Tim Smith wrote:
RichTO90 wrote: The simple facts, which you may chose to ignore if you wish, was that the capitol units of the KM only figured in Seelöwe as diversions.
I'm not ignoring or disputing that. Nowhere have I claimed that Hipper and Scheer would be directly escorting the invasion fleet.

I am claiming Hipper and Scheer would be sent out on diversions. A diversion is 'protecting the troops'. Indirectly protecting them.
I wonder about how effective the diversions would be. The only reason to use these ships as a diversion is to pull RN units away from the invasion area. However, would any units actually be pulled away from the Channel? Surely if these KM units were sighted, the RN would send its capital ships to engage them, not the destroyers and cruisers that would be used in the Channel to counter an invasion.

Did the RN actually plan to use the capital ships in the Channel except in an extreme emergency?
As elaborate as the "Herbstreise" was planned I cannot see how RN could not have taken it into consideration. After all, untill summer '40 many in the British establishment still saw a landing on the East coast as the most probable. I believe there also was a scheme involving Ireland....?

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Post by LWD » 01 May 2007 12:59

Well there are two basic diversions:
1) raiders breaking out into the Atlantic - this was restricted to one CA I believe
2) Faked invasions - Here we have three light cruisers and some liners.

2) could actually be counter productive. The slow BB's of home fleet wouldn't be of much use chasing down a raider. The plan as I read it was not to use them in the channel. The obvious place to use them then would be against a possible attack between Newcastle and Aberdeen (where 2 was to threaten). Once they are at sea in this area the temptation to use them in the channel when the faint is clear will be very strong.

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Post by fredleander » 01 May 2007 14:41

LWD wrote:Well there are two basic diversions:
1) raiders breaking out into the Atlantic - this was restricted to one CA I believe
2) Faked invasions - Here we have three light cruisers and some liners.

2) could actually be counter productive. The slow BB's of home fleet wouldn't be of much use chasing down a raider. The plan as I read it was not to use them in the channel. The obvious place to use them then would be against a possible attack between Newcastle and Aberdeen (where 2 was to threaten). Once they are at sea in this area the temptation to use them in the channel when the faint is clear will be very strong.
Before I elaborate more on this. What would you say is most important in this context - what we know today or what it looked like for the British (Admiralty) at the time? And what did the Admiralty know about the condition of the German fleet? Do you have more details on the "Herbstreise", please? To take that one first.

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Post by LWD » 01 May 2007 17:12

Most of what I've read on the diversions is summerised at:
http://www.axishistory.com/index.php?id=1145

Actually it has to be a combination. For instance the British wouldn't know how many raiders the Germans could sortie with. The Germans might have thought that they could have sortied with 2 but we currently know that if they had tried to sortie with Hipper she would have broken down much like she did in the trials that took place instead of her sortie.

So we have to use a combination of current knowledge and the German plans to figure out what they could have done. Then a combination of what the British knew or would have known and what we know to determine the reaction and it's effect.

For instance if the Germans soried a CA into the Atlantic if the British don't notice until after Sea Lion is underway then they are probably not going to react to it.

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Post by fredleander » 08 May 2007 15:13

LWD wrote:Most of what I've read on the diversions is summerised at:
http://www.axishistory.com/index.php?id=1145

Actually it has to be a combination. For instance the British wouldn't know how many raiders the Germans could sortie with. The Germans might have thought that they could have sortied with 2 but we currently know that if they had tried to sortie with Hipper she would have broken down much like she did in the trials that took place instead of her sortie.

So we have to use a combination of current knowledge and the German plans to figure out what they could have done. Then a combination of what the British knew or would have known and what we know to determine the reaction and it's effect.

For instance if the Germans soried a CA into the Atlantic if the British don't notice until after Sea Lion is underway then they are probably not going to react to it.
"Sure" to everything. But what did the Admiralty really know about the German "heavies".....? And how could they not take them into consideration if they didn't know anything.

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Post by LWD » 08 May 2007 16:27

Well they would have had some damage reports for the damaged KM units. They've enough experiance to know that you don't repair torpedo damage quickly. For at least some of the German vessels I assume they also had relativly fresh photos taken by recon planes. I don't know how much info came in via "humint" or from Ultra but probably enough so that they have a decent idea what's available. (They have little reason not to assume that Hipper and Sheer are available and maybe one of the twins a possible) On the otherhand once the invasion is underway it is of critical importance. A raider or two loose in the Atlantic is not as important as defeating the invasion.

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Post by fredleander » 09 May 2007 09:01

LWD wrote:Well they would have had some damage reports for the damaged KM units.
What do we know about that..... If I'd posted a similar opinion I'd be slaughtered.... :)
LWD wrote:They've enough experiance to know that you don't repair torpedo damage quickly. For at least some of the German vessels I assume they also had relativly fresh photos taken by recon planes. I don't know how much info came in via "humint" or from Ultra but probably enough so that they have a decent idea what's available. (They have little reason not to assume that Hipper and Sheer are available and maybe one of the twins a possible) On the otherhand once the invasion is underway it is of critical importance. A raider or two loose in the Atlantic is not as important as defeating the invasion.
Prinz Eugen was running up - Bismarck was also out of the wharf...... :).....The RN wouldn't know if Hipper or Scheer would not support the "Herbstreise". We know they were planned for Atlantic diversions. The RN didn't. The important point is how would the "Herbstreise" look from the British side. We know it was a diversion.....And, talking about Ultra, there were also to be active radio deception going on at the same time.

They wouldn't know about Lützow, Scharnhorst and Gneisenau. The latter was "out" in October, I believe.

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Post by LWD » 09 May 2007 14:08

leandros wrote:
LWD wrote:Well they would have had some damage reports for the damaged KM units.
...
They've enough experiance to know that you don't repair torpedo damage quickly. ...
Prinz Eugen was running up - Bismarck was also out of the wharf...... :).....The RN wouldn't know if Hipper or Scheer would not support the "Herbstreise". We know they were planned for Atlantic diversions. The RN didn't. The important point is how would the "Herbstreise" look from the British side. We know it was a diversion.....And, talking about Ultra, there were also to be active radio deception going on at the same time.

They wouldn't know about Lützow, Scharnhorst and Gneisenau. The latter was "out" in October, I believe.
First lets' address the question what the British would/could have known. The Gneisenau and Lutzow were torpedoed by British submarines that survived so it can be expected that that was known. It's not clear what was known about Scharnhorsts damage or when since Acosta along with her consorts was sunk. However both the BBs put into Trondheim before mving to Kiel and Scharnhorst was attacked their by RN aircraft. I don't have anything specific on air recon over Kiel but since the British bombed it the year before it was obviously in range and of some interest so occasional photo recon flights were likely. I tried looking for some details but haven't found any in that regard yet. By the way http://www.german-navy.de/kriegsmarine/ ... rions.html list Gneisenau as "in dock" until December if they mean dry dock by that this would show up on airial photos. The British also have a pretty good idea how long it takes to work up a ship in general and have prewar info on how long the Germans took to work up some of their ships so they are not going to expect Eugen or Bismark to be available. So they would be worried about protecting against breakouts by Hipper and Sheer. It is not clear what they knew for certain about the others in September and October but they probably considered them questionable at best.

There is no reason for them to change their historical stance until something significantly ahistorical happens. Historically Sheer broke out in October. Hipper didn't make it to Kiel before her engines failed. So the 2 major a historical possiblities are:
1) Sheer attempts to break out in September (or if the invasion is in October earlier in October).
2) The light cruisers and liners launching their feint.

As far as Sheer breaking out there are two possiblities:
1) She doesn't make it and is either sunk or damaged or possibly returns undamaged. If she is sunk or damaged then she is out of the equation for a while other wise it's back to the historical case.
2) She breaks out. Since slow BB's aren't likely to be very good at hunting her down cruisers and BCs are likely to be given this task although a slow BB or two may escort important convoys. This is probably the ideal German case. However since Hipper is still considered a threat the British have to leave some ships available to guard against her breaking out.
So Sheer's breakout at best draws off a few cruisers and perhaps an old BB or two.

The light cruisers and liners present a more significant threat in some ways as the British will believe that they have a chance of landing troops. However the coast of northern England is out of effective aircover range for these ships so countering an invasion becomes a reasonable task for the slower BBs at Scapa. If they respond they are likely to stay at sea for a while particularly if the LCs and liners repeat the feint the next day. That leaves the British heavy units actually closer to the invasion fleet when it is detected. Since slow cargo ships and barges form a major part of the real invasion fleet a feint with them is unlikely. This introduces the possiblity that the fient actually draws British heavy units into the battle. It looks to me like the purpose of the feint is to get the British to commit their land forces to the north of England as these would require more time to reorient. In this they are likely to succeed but if the Germans can't get major infantry foces ashore in good condition and order that will have little impact.

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Post by RichTO90 » 09 May 2007 21:31

leandros wrote:Prinz Eugen was running up - Bismarck was also out of the wharf...... :).....The RN wouldn't know if Hipper or Scheer would not support the "Herbstreise". We know they were planned for Atlantic diversions. The RN didn't. The important point is how would the "Herbstreise" look from the British side. We know it was a diversion.....And, talking about Ultra, there were also to be active radio deception going on at the same time.

They wouldn't know about Lützow, Scharnhorst and Gneisenau. The latter was "out" in October, I believe.
Typical RN reaction to such an event:
28 September 1940
On a report of a German heavy cruiser escorting a convoy at 1400, possibly escorted by heavy cruiser HIPPER off Norway in 62‑00N, 3‑30E, sixty miles off Stavanger, battlecruiser REPULSE (Flag Rear Admiral Destroyers Home Fleet), heavy cruisers BERWICK and NORFOLK, and destroyers MATABELE, PUNJABI, DUNCAN, SOMALI, and ESKIMO departed Scapa Flow at 2015 to intercept.

Battlecruiser HOOD, anti-aircraft cruiser NAIAD, and destroyers ZULU, TARTAR, and ELECTRA departed Rosyth to intercept the German force.

No contact was made and the operation as cancelled at 0909 on the 29th.
The 'deception' thus lasted 12 hours and 53 minutes and 'diverted' half the battle units of the Home Fleet (2 BC out of 2 BC and 2 BB at Scapa and Rosyth), the two heavy cruisers at Scapa (none were at Rosyth), one of four AA cruisers, and 8 of 24 DD and DE. Battleships Nelson and Rodney, AA light cruisers Bonadventure and Cairo, 10 destroyers, 4 sloops, a Norwegian torpedo boat, and two submarines remained at Rosyth. Carrier Furious, Monitor Erebus, light cruiser Glasgow, AA cruiser Curacao, a destroyer and a sloop remained at Scapa.

(Note: edited to correct dispositions at Scapa and Rosyth).

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Post by RichTO90 » 10 May 2007 18:12

leandros wrote:Prinz Eugen was running up - Bismarck was also out of the wharf...... :).....The RN wouldn't know if Hipper or Scheer would not support the "Herbstreise". We know they were planned for Atlantic diversions. The RN didn't. The important point is how would the "Herbstreise" look from the British side. We know it was a diversion.....And, talking about Ultra, there were also to be active radio deception going on at the same time.

They wouldn't know about Lützow, Scharnhorst and Gneisenau. The latter was "out" in October, I believe.
Actually Donald P. Steury in his article "Naval Intelligence, the Atlantic Campaign, and the Sinking of the Bismarck: A Study of the Integration of Intelligence into the Conduct of Naval Warfare" (Journal of Contemporary History, Vol 22, No. 2) looks in part at just this subject.

British intelligence at this time relied primarily on radio direction finding and signals traffic analysis, HUMINT - agents reports and information garnered from Swedish naval sources - and direct surface and air reconnaissance. ULTRA had little impact on naval intelligence, since the KM Enigma codes were essentially secure until after the New Year. Luftwaffe decrypts did give some insights, especially on major ship movements, but otherwise the British relied on direction finding for German ship movements and signals analysis on ship identifications. Air reconnaissance was not used for the major KM ports at this time unless as part of a Bomber Command mission, which was unusual, Kiel and Wilhelmshaven were simply too well defended at this time. However, short-range coverage of the Low Country and French Channel ports was generally extensive. Otherwise it was the standing cruiser patrols covering the two possible routes out of the North Atlantic around Iceland that were critical.

So the British from pre-war intelligence had a good knowledge of German naval strengths and construction. They also had some reports of damage inflicted on German ships. they had pretty good means of detecting German attempts to breakout through the North Sea, but they were ny no means infallible (when the twins sortied in late January 1941 after completeing repairs in December 1940 - not October 1940 leandros, trying to pull one over on us again? - Naiad actually tracked them for Hovey's massive sortie, but then lost them when Lutjen's turned away and ran north, allowing them to breakout into the Atlantic....British ship-based surface search radar wasn't as good as that on the German capital ships at this time).

But here are some of the problems. :D

1). The German diversionary plan, like all such, only works if the British detect the German diversionary force. Otherwise there is no effect on Seelöwe operations and British reactions. That means the Germans must risk actually losing their remaining capital ships by physically revealing themselves to British reconnaissance in the North Sea....and that cannot be done by ships docked at Kiel, Wilhelmshaven, or working up in the Baltic. :D

Which means the diversionary force is reduced to the three light cruisers and one training ship escorting the liners of Herbstreise. Which the forces at Scapa are more than adequate to deal with.

2). If British naval intelligence at this time is limited, German naval intelligence is non-existent. :D Quite simply they had little idea of the strength or dispositions of the British fleet elements. The Luftwaffe was actively hostile on the subject of diverting reconnaissance elements to naval matters and the KM cooperation squadrons, such as they were, were fully tied up in helping to maintain operations in Norway. So there was little or no aerial reconnaissance of the British fleet bases.

Nor were there sufficient U-Boot to establish pickets off British bases, which after Royal Oak was pretty suicidal in any case. Anyway, Seelöwe required the use of all U-Boot assets available to try to close off the Channel entrances and would have required all boats on Atlantic patrol to be withdrawn as well.

Worse, the B-Dienst lost the Admiralty codes in August and did not get back into the new codes until late in the year. Nor did they have the high-frequency direction finding capability of the British, so could not use that do track British movements.

So German operations would occur in an intelligence vacuum. At best the 'diversion' would 'draw off' the Home Fleet elements at Scapa, which were there precisely for that purpose. In other words, the 'diversion' would actually 'divert' nothing. :lol: 8-)

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Post by LWD » 10 May 2007 18:51

Well if they tried sortieing with Sheer and/or hipper and lost them or even had them turned back with damage it would actually free up assests

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Post by RichTO90 » 10 May 2007 19:54

LWD wrote:Well if they tried sortieing with Sheer and/or hipper and lost them or even had them turned back with damage it would actually free up assests
Sorry, I know it's hard to keep track in this mish-mash :D , but:

Scheer isn't available until 23 October 1940 when she completes her working up after her extensive rebuild and refit. She was not part of the Seelöwe planning.

Hipper was part of the plan but suffered a major propulsion failure on 30 September while running sea trials after her own refit. Thus she wasn't available prior to 30 September, then broke down and wasn't available until 28 October after repairs were completed.

So the first wasn't part of the diversion planning and could not have participated while the second was part of the plan but also could not have participated. :D

And no assets would have been freed up, the Home Fleet at Scapa was always going to maintain a presence to block the North Sea exits. :D Not that it matters. :D

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Post by LWD » 11 May 2007 13:40

I thought someone said Sheer was available. Agreed on Hipper unless they had neglected here shakedown and taken it very easy on her until she reached Kiel. Of course then the failure would likely have happened where the RN could reach her. In this case with all known German heavy units not available I suspect the RN could have broken loose a few ships to help with the invasion if they saw the need. Not at all sure they would see the need however. I can see RN captains takeing as liberal an iterpretation of their orders as possible if it would let them get a crack at the invasion fleet.

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Post by RichTO90 » 11 May 2007 14:42

LWD wrote:I thought someone said Sheer was available. Agreed on Hipper unless they had neglected here shakedown and taken it very easy on her until she reached Kiel. Of course then the failure would likely have happened where the RN could reach her. In this case with all known German heavy units not available I suspect the RN could have broken loose a few ships to help with the invasion if they saw the need. Not at all sure they would see the need however. I can see RN captains takeing as liberal an iterpretation of their orders as possible if it would let them get a crack at the invasion fleet.
'Someone' always says 'something' but that doesn't always make it true. And Hipper is not a maybe or maybe not, her repairs and shakedown had been completed on 9 September, the failure occured while she was in an operational status on 30 September. The problem was her powerplant design and not stress, like many of the KM vessels she was prone to breakdown.

And again I think you miss the point, it doesn't matter whether or not the Royal Navy knew or did not know that the KM heavy units were or were not operational, the units left at Scapa, reindorced if neccessary by the forward deployed units at Rosyth, were more than enough to deal with such a contingency. But the units at Rosyth were purposely meant to be there as a reaction force to the invasion and only secondarily to react to a breakout attempt, the 'few' ships to help with repelling the invasion were :D :

2 BB: Nelson, Rodney
1 BC: Hood
3 CLAA: Naiad, Bonadventure, Cairo
13 DD: Cossack, Maori, Sikh, Zulu, Jackal, Kashmir, Kipling, Ashanti, Bedouin, Punjabi, Tartar, Electra, Vortigern

Of course, with Forbes, the CinC of Home Fleet present there on Rodney, I somehow doubt that many of the captains would be making very liberal interpretations of their orders. :D

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