Luetjens chooses the Iceland-Faeroes Gap instead

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby A Raven » Thu May 28, 2015 6:38 pm

As a postscript to my earlier message about supply ships; To quote from the book 'Cruiser Operations' by Raven "From the 7th of May to the 11th of July, a total of 15 German supply and support ships had been intercepted, 8 of these by the use of Special Intelligence."

Erskine's reasons for dismissal of the value of the capture of U 110:
Quote from his afterword; " While BP received an Enigma machine and rotors from U 110, they did not help, since BP already held several machines and all eight Enigma rotors. No Hydra Allgemein Enigma keys were taken from U 110, although an Offizier keylist for April was seized. The 'Einstellung and Buchstaben" (settings and letters) recovered from U 110 for April and June were not Enigma keys, but merely recognition signals for use with flares and signal lamps."




Dave Saxton wrote:Retaining contact long enough to bring the Home Fleet battle groups in is the main problem for the British as I see it. Catching a glimpse of the enemy is one thing, but shadowing for hours on end is quite another. Unless there are prolonged periods of unlimited visibility- rather unlikely-it seems a difficult task without capable surface search radar. For example, when the Scharnhorst and Gneisenau tried the Gap previously they were spotted by a British cruiser briefly. The cruiser was unable to retain contact. It reported that it had seen the Hipper. The Germans will know by local radio intercepts if they were being shadowed or not as they did historically.

When the Scheer came back through the Denmark Strait in March of 41 its radar warned it of an approaching patrol in time to duct into a near by fog. This was a daylight encounter. They watched the British cruiser steam by. The British look outs never saw the Scheer. A second encounter came at night. In this case the Scheer's radar was not operating because the moisture resistant cases had been carelessly not closed up. The Scheer suddenly found it self in the wake of an enemy cruiser no more than 3,000 meters away on a bright star lit night. But once again the British look outs never saw the Scheer. This was in the Denmark Strait so the Germans really had no where to go. Such were the difficulties faced by the British patrols in any of the northern passages.

As Mr Raven points out, Enigma Intel will be available after the 29th due to the capture of Enigma keys from U-110 and the weather ships. The British could use Ultra Intel to help find Luetjens once out in the Atlantic by the arrangement of meeting of supply ships. The keys were not those used by surface warships in distant waters, but Prinz Eugen will need frequent re-fueling. The British will need to be careful in the use of this Intel so that the Germans don't become wise to it and change the keys.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Dave Saxton » Fri May 29, 2015 4:33 am

Thank You for that information on Naval Ultra. It is most interesting.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Herr Nilsson » Sat May 30, 2015 11:47 am

Dave Saxton wrote:Bismarck had a radar detector we now know,...


Do we know?
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Marc

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Dave Saxton » Sat May 30, 2015 3:21 pm

Herr Nilsson wrote:
Dave Saxton wrote:Bismarck had a radar detector we now know,...


Do we know?


Yes. Helmuth Giessler reported that Group West had a custom unit built following Operation Berlin and shipped to Bismarck before Rhine Exercise. This detector was not a Metox or a proto-Metox. It detected the pulse repetition rate of enemy radar as a primary mode of detection, but likely could identify the wavelength as well because Group West asked Luetjens to record the wavelengths of enemy radar detected. Giessler reports that its directional accuracy was rather poor but this also indicates that it could at least determine the general direction.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Herr Nilsson » Sat May 30, 2015 4:42 pm

Giessler wrote:

Es läßt sich nicht mehr feststellen, ob auf Bismarck das Versuchsmuster eines Funkmeßbeobachtungsempfängers eingebaut war. Die auch vom Verfasser geäußerte Annahme, daß ein solches Gerät an Bord war, konnte nicht bestätigt werden.


That means it was just an assumption and couldn't be confirmed.
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Marc

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Dave Saxton » Sat May 30, 2015 6:14 pm

Yes, but it's a safe assumption given Group West's recorded request. It is rather unlikely that Group West would have requested they determine the wavelengths of the enemy radar being used if they had no means of doing so.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Herr Nilsson » Sun May 31, 2015 10:53 am

There is a lenghty German SKL memo from end of June 1941 discussing just the one sentence about the British radar from Lütjens famous long signal:

The Germans didn't know the wavelenght of the reported British naval radar set. From the German point of view it was possible that the British ships had devices using a similar wavelength like their own radar and now there was an opportunity to determine it.

Der Kommandant des Kreuzers "Prinz Eugen" hat gemeldet, dass keine britischen Deteimpulse aufgenommen worden sind; das bestätigt jedoch - da keine anderen Beobachtungsgeräte an Bord waren - nur, dass etwa vorhandene britischen Dete-Geräte nicht in der Nähe der deutschen Em-II-Welle arbeiten.


So they could confirm that the wavelength wasn't similar.

It was also discussed, if the British possibly had radar detectors. It was considered possible, but I would expect that a similiar device on Bismarck would have been mentioned. It wasn't. Instead the experience with German radar detectors at English Channel were described.

Lütjens signal from May 25th at 0727 - that he was still beeing shadowed - was attributed to the usage of Bismarck's own Em-2. Not a single word about a possible radar detector.

It's also mentioned that Lützow was the first ship equiped with a radar detector.
Die Ausrüstung begann bei Kreuzer Lützow,...
Once again no word about Bismarck.

Therefore I'm not so confident that it's a safe assumption.
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Marc

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby A Raven » Sun May 31, 2015 12:17 pm

When you quote from German documents, could you please translate into the English language? Thank you.

If Bismarck was fitted with an intercept set, it is likely that it would have been to take in signals from type 79 and 279 radars. The Germans knew the characteristics of these sets and had intercept stations set up along the French, Dutch and German coasts by late summer of 1940, and in the Mediterranean around December of the same year. These sets were tuned to intercept, only types 79 and 279. Types 284, 285, 286 and 281 remained unknown to the Germans until well into 1941 when numbers of ships began to be fitted.

Looking at photos of the Bismarck, I cannot see any purpose built aerial arrays for intercepting radar signals. If I am correct, then any aerials for said purpose would probably have been a lash-up affair comprised of TWO horizontal wire dipoles. This would give a degree of Dfing. It would also make it almost impossible to distinguish these wires from the radio aerials.

The first RN shipborne radar intercept set did not go to sea until well into 1941, on the monitor Cerberus. Type FV1, and it was not until early 1942 that other ships were fitted.



Herr Nilsson wrote:There is a lenghty German SKL memo from end of June 1941 discussing just the one sentence about the British radar from Lütjens famous long signal:

The Germans didn't know the wavelenght of the reported British naval radar set. From the German point of view it was possible that the British ships had devices using a similar wavelength like their own radar and now there was an opportunity to determine it.

Der Kommandant des Kreuzers "Prinz Eugen" hat gemeldet, dass keine britischen Deteimpulse aufgenommen worden sind; das bestätigt jedoch - da keine anderen Beobachtungsgeräte an Bord waren - nur, dass etwa vorhandene britischen Dete-Geräte nicht in der Nähe der deutschen Em-II-Welle arbeiten.


So they could confirm that the wavelength wasn't similar.

It was also discussed, if the British possibly had radar detectors. It was considered possible, but I would expect that a similiar device on Bismarck would have been mentioned. It wasn't. Instead the experience with German radar detectors at English Channel were described.

Lütjens signal from May 25th at 0727 - that he was still beeing shadowed - was attributed to the usage of Bismarck's own Em-2. Not a single word about a possible radar detector.

It's also mentioned that Lützow was the first ship equiped with a radar detector.
Die Ausrüstung begann bei Kreuzer Lützow,...
Once again no word about Bismarck.

Therefore I'm not so confident that it's a safe assumption.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Dave Saxton » Sun May 31, 2015 2:34 pm

It is not just Giessler's safe assumption # ( He was fairly certain or he would not bring it up, but he did qualify it properly) and the recorded request from Group West. There is also testimony confirming Henning von Schultz' report that Bismarck was equipped with a radar warning receiver alluded to by the Baron (although the Baron incorrectly listed it as a Metox) in private correspondence, that I have been asked not to go into details about in public -so I will not.

Interesting about the Luetzow having been equipped with an early model warning receiver. I know from descriptions of its use that it used PRF as the primary mode of detection, like the Bismarck one assumed by Giessler, and that it apparently detected transmissions below 60 cm prior to the recovery of the Rotterdam Geraete.

That these reports did not garner any attention or that Bismarck is not specifically mentioned in available documents is not surprising because of the severe secrecy about all things radar that existed within the kriegsmarine.

Since the Bismarck and its records were lost, we can not have the 100% confirmation you are seeking, but this is not abnormal in historical research as you know. I think it is a safe assumption but I could be wrong. And I thank you for expressing your opinion on this matter and I respect it.

* Berenbock wrote that a shore based detector built by the NVA, detected 9 cm transmissions in the North Sea as early as 1941 but this was dismissed as an anomaly.

# Giessler was in a position to know more than most because of the posts he held during the war including at the MND. That he could not refer to documentation by the time he wrote about this during the late 1960s is not surprising since much documentation pertaining to KM radar no longer existed-and much documentation never existed.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Herr Nilsson » Sun May 31, 2015 6:22 pm

Dave Saxton wrote:It is not just Giessler's safe assumption # ( He was fairly certain or he would not bring it up, but he did qualify it properly) and the recorded request from Group West. There is also testimony confirming Henning von Schultz' report that Bismarck was equipped with a radar warning receiver alluded to by the Baron (although the Baron incorrectly listed it as a Metox) in private correspondence, that I have been asked not to go into details about in public -so I will not.


Giessler backpedaled in 1971. Josef Kaiser once told me the Baron didn't even know that Bismarck had two different 10,5 cm Flak-mountings and Hans-Henning von Schultz was on Prinz Eugen not on Bismarck. What about the "severe secrecy" you mentioned?

Dave Saxton wrote:That these reports did not garner any attention or that Bismarck is not specifically mentioned in available documents is not surprising because of the severe secrecy about all things radar that existed within the kriegsmarine.


The document I quoted is about all kinds of detection during Rheinübung and it includes detailed instructions how to use GHG, UT, Em-2 and so on in the future. It also states that Lützow has still received (or is receiving) a radar detector and the other ships will receive it automatically in a certain order and don't have to request. There is no need to keep a radar detector on Bismarck secret in this memo.

Dave Saxton wrote:Since the Bismarck and its records were lost, we can not have the 100% confirmation you are seeking, but this is not abnormal in historical research as you know. I think it is a safe assumption but I could be wrong. And I thank you for expressing your opinion on this matter and I respect it.


That means we don't know, right?
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Marc

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Dave Saxton » Sun May 31, 2015 7:41 pm

Okay
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Paul L » Wed Oct 14, 2015 7:50 pm

http://www.wetterzentrale.de/topkarten/fsslpeur.html

If you follow this site from May 19 1941 through May 25 1941 it shows the initial low pressure front that dominated the Denmark Straits was shifting south east over the Faros gap on 22-23nd and then Northern Scotland 24rd and Iceland to Ireland on the 25th. So Faros gap would have been a better bet anyway.
"Eine mal is kein mal"

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Paul L » Thu Oct 15, 2015 5:10 am

http://www.naval-history.net/xDKWW2-4105-32MAY02.htm

In the Iceland-Faroes Channel were light cruisers MANCHESTER and BIRMINGHAM and five trawlers. The two light cruisers refuelled in the Faroes to refuel on the 22nd. Light cruiser ARETHUSA, which arrived at Reykjavik on the 21st, was sent to reinforce these ships.

Heavy cruiser NORFOLK was patrolling in the Denmark Strait. Heavy cruiser SUFFOLK, after refuelling at Hvalfjord on this date, returned to reinforce this patrol.


On the 22nd there were three British cruiser and several trawlers over a 250nm distance to cover this area in low pressure dominated seas. That means visibility would be marginal at best and even with fixed radar one of the cruisers -could not be expected to detect much more than one in three. With one fixed Radar cruiser @ 20-30nm range and two regular cruisers + 5 trawlers at 5-10nm visible -that's at most 55-100nm coverage on 250nm or 28-40%. But such early radars were not good performers in low pressure weather, so the actual detection chance may be 15-25%. Further more if a trawler is detecting the KM ships they will likely be destroyed in any encounter and have zero chance of shadowing , thus allowing Lutjens his first escape maneuver undetected.

If Lutjens is detected he just doubles back to the Artic and waits a week just like in Operation Berlin. This could mean Bismarck doubles back to Bergen and tries again later. If the mission is scrubbed the British cruisers can't go hunting the german tankers since all those cruisers will be needed to man the Northern Patrol...etc etc.
"Eine mal is kein mal"

A Raven

Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby A Raven » Sun Oct 18, 2015 2:07 pm

The Iceland Faeroes Gap was effectively closed by extensive mine barriers; deep and shallow. For the Bismarck to transit this passage would have far too risky. See my earlier message.

Re your last sentence, "If the mission is scrubbed ...." This is invalid as most of the German supply ships were rounded up by HM vessels that were NOT part of the Northern Patrol. To my knowledge, ALL of the German ships were stationed well south of the patrol line before the Bismarck sortied. It helps if one knows WHICH ships were used in this round up. You might try Roskill as a starting point.


Paul L wrote:http://www.naval-history.net/xDKWW2-4105-32MAY02.htm

In the Iceland-Faroes Channel were light cruisers MANCHESTER and BIRMINGHAM and five trawlers. The two light cruisers refuelled in the Faroes to refuel on the 22nd. Light cruiser ARETHUSA, which arrived at Reykjavik on the 21st, was sent to reinforce these ships.

Heavy cruiser NORFOLK was patrolling in the Denmark Strait. Heavy cruiser SUFFOLK, after refuelling at Hvalfjord on this date, returned to reinforce this patrol.


On the 22nd there were three British cruiser and several trawlers over a 250nm distance to cover this area in low pressure dominated seas. That means visibility would be marginal at best and even with fixed radar one of the cruisers -could not be expected to detect much more than one in three. With one fixed Radar cruiser @ 20-30nm range and two regular cruisers + 5 trawlers at 5-10nm visible -that's at most 55-100nm coverage on 250nm or 28-40%. But such early radars were not good performers in low pressure weather, so the actual detection chance may be 15-25%. Further more if a trawler is detecting the KM ships they will likely be destroyed in any encounter and have zero chance of shadowing , thus allowing Lutjens his first escape maneuver undetected.

If Lutjens is detected he just doubles back to the Artic and waits a week just like in Operation Berlin. This could mean Bismarck doubles back to Bergen and tries again later. If the mission is scrubbed the British cruisers can't go hunting the german tankers since all those cruisers will be needed to man the Northern Patrol...etc etc.

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Re: Luetjens chooses the Iceland-Faeroes Gap instead

Postby Paul L » Thu Oct 22, 2015 2:50 am

would not worry about a compromised supply net work. KM had many more to activate and Raeder was doing this for an early 1942 sortie when Hitler recalled the fleet to Norway were he could better control them.


No offence intended but counting on mines was pointless since GIUK was used through out the war by Uboats & other merchant ships . As I recall from O'Hara 3/4 got through until mid to late 1943, when networks were finaly shut dow3. Even then 1/4 of these ships got through.

As a matter of interest allies lost 534 vessels to 223,000 KM mines deployed that's 418 mines per ship destroyed. RN deployed 264,000 mines sinking only 759 ships or 348 mines per ship destroyed. In truth the figure in the GIUK would be much higher since most mining campaign was directed at KM coastal convoys.

So such minefields were not very effective.
"Eine mal is kein mal"


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