Denmark Strait - Run ?

[Karl Heidenreich]

wadinga:

No need to convince about Lutjens...

[Vic Dale]

News of my loss of citizenship is somewhat premature.

Mention has been made in this thread of Lutjens making a long signal thus betraying the position of his ship. The duration of this signal was supposed to be 30 minutes, but this like so many other navy tales is utterly false.

A series of four signals sent by Bismarck inside a 30 minute period, were intercepted by Bletchley Park and were patched together into one single message using the continuation marks. So there was no long signal until it got to Bletchley.

The KM was using a protocol which limited any enigma communication to 250 characters. It has been suggested that some U-Boats broke this rule, but detailed and exhaustive investigation has shown that this was never the case. All obeyed the instruction. So too did Bismarck. The text of the signal breaks down into 4 sections of 250 characters including spelled numerals. Any deviation from this protocol by Lutjens or his subordinates would have been seized upon and used to further denigrate him.

The transmission began at 0401 as denoted by the Uhrzeit or Time segment, which is to do only with the time of transmission, as transmitter/receiver stations had their hours broken up into transmission and receiving segments, four of each in every hour and staggered between them so that there was reception of signal available at more than one German receiving station at any given time.

The transmission would not include anything in code which was not signal text. The address would not be encrypted and nor would the time or date of transmission as this could give a dangerous crib to enemy decrypters.

The finished signal itself would be sent by teleprinter with a 60 word per minute send speed. This would mean basically that a 250 word signal would be sent within 40 or 50 seconds. Insufficient time for a shipboard DF unit to get a fix. DF units on mainland Britain would not get the necessary cross bearings to get a proper fix, so Lutjens did not betray his position with that or any other signal.

Incidentally the German ship was one hour behind the British, so the signal was out and away before 0600.

Bismarck was only intercepted on the morning of the 26th by preset Coastal Command Patrols working in teams constantly across the Biscay.

Lutjens managed to get PG safely away to fuel, and he also eluded his pursuers for 30 hours despite the fact that he was being pursued by ships with good radar and a carrier with air surveillance capability of 200 miles (better than any radar).

His flagship sustained damage during the battle with Hood and PoW, the worst possible circumstance he could wish to encounter. He and his captains fought their way out. He had fuel enough to get him direct to France, so there was no need to hang around in the Mid-Atlantic looking for a tanker and an opportunity to fuel. Had he been short of fuel he would hav gone for the tanker. Hence his signal,

"Due to fuel heading direct to France."

Damage was the imperative driving him toward France not fuel. He had enough to steam at high speed direct had he chosen to.

The ship was about to come under German Air Cover soon after Midnight on the 26th, so without that hit in the rudders he would probably have made it as there was nothing heavy lying between him and the French ports.

The operation faced a very large naval force which had been stung by the failure to catch and sink the twins and which had now been reinforced, regrouped and was fully open for business. Lutjens was lucky to get as far as he did, as had Hood survived he would have been destroyed in the Denmark Straight. Fighting his way out and getting away for 30 hours is a testimony to his ability.

As for the delay in opening fire. If a German or Italian does it it is cowardice and hesitation. If a Brit or an American does it they are coldly and calmly waiting to see the whites of the enemy's eyes before firing. A simple matter of nationalistic interpretation.

Vic Dale

[Karl Heidenreich]

Vic Dale:

As for the delay in opening fire. If a German or Italian does it it is cowardice and hesitation. If a Brit or an American does it they are coldly and calmly waiting to see the whites of the enemy's eyes before firing. A simple matter of nationalistic interpretation.

Months ago I would have never, ever, agreed to that but it´s not the case now. I´m in a position of re examining a lot of the previous stuff and whilst not very convinced, yet, of Lutjens´particular performance at DS (and before or after the battle) I´m less keen to condem or critize him as I was before. I think that I´m a hard learner but I learn sooner or later. I do concur, completely, with the statement quoted before due to personal experience, precisely with that.

I´m also very interested in this issue of the comunication lenght of Lutjens with Germany. Being that the case which consequences, or lack of them, could we conclude of the episode?

Best regards,

[Byron Angel]

Vic,

Thanks for a very informative post. Most interesting re German radio message transmission techniques.

Question - Do you happen to know when the Germans went to burst transmission of compressed signals? Was it possible to transmit in this fashion from both shorestations and vessels or from shore stations only?


Byron

[mcubed]

The finished signal itself would be sent by teleprinter with a 60 word per minute send speed. This would mean basically that a 250 word signal would be sent within 40 or 50 seconds. Insufficient time for a shipboard DF unit to get a fix. DF units on mainland Britain would not get the necessary cross bearings to get a proper fix, so Lutjens did not betray his position with that or any other signal.

Vic Dale

So all the histories claiming that USN/RN/RCN use of HF-DF was important in the battle against the
U-boots are incorrect?

[Byron Angel]

So all the histories claiming that USN/RN/RCN use of HF-DF was important in the battle against the
U-boots are incorrect?

Good overview on RN HF/DF development here - http://www.naval-history.net/xGM-Tech-HFDF.htm

HF/DF was only just starting to be fitted to RN ship at the time of the BISMARCK episode. As well, it was of limited range (ony 12-14 miles max, according to the article).


Byron

[Dave Saxton]

Yes, we must be careful not to confuse Huff Duff with the massive shorebased facilities (that everybody had) to intercept and triangulate the approximate loaction of a transmitting source of long range wireless traffic. Huff Duff was a local, short range, shipboard, DFing tool that could locate a nearby U-boat broadcasting to report the location of a convoy, or otherwise help orgainze wolfpacks in attack. The wolfpack tactics required extensive wireless communications among the u-boats themselves and with U-boat command ashore. Huff Duff didn't become employed extensively until a bit later during the war.

[tommy303]

A lot more credit for success was also being given HF/DF during and after the war until the public disclosure of Ultra; during the war to keep the Germans from recognizing their codes were compromised, and afterwards to keep the many eastern block countries unaware as Enigma formed a basis for their many codes.

[RF]

Coming back to Vic's post, I don't know whetherI have missed something but I understand that a directional fix (albeit wrong because it was plotted on an inappropriate chart) was obtained on Bismarck from this transmission or set of transmissions; it would therefore seem to me the communications were a giveaway....

The comment about Lutjens being skilled enough to get out of a hole at DS does need to be put into context. He was aided by the tactics of Holland, coming in at the angle that had been forced on him after losing the enemy plot hours before when he was in a more favourable position to intercept, and then Hood opening fire on the wrong ship. Vic is right about saying Bismarck should have been destroyed at DS - on paper. Fortunately for Lutjens the proverbial wheel fell off for Holland, and it was only Leach's insubordination that prevented a total fiasco. Having said that Lutjens did take advantage of the position as it unfolded, even though he then failed to pursue POW when that ship broke off.

[Vic Dale]

Vic,

Thanks for a very informative post. Most interesting re German radio message transmission techniques.

Question - Do you happen to know when the Germans went to burst transmission of compressed signals? Was it possible to transmit in this fashion from both shorestations and vessels or from shore stations only?


Byron

My understanding it that Burst Transmission was a very late development and was not possible at that time of the war. Burst transmission would only be possible on a super-fast teleprinter, using a pre-cut punch-hole tape.

Vic Dale

[Vic Dale]

The finished signal itself would be sent by teleprinter with a 60 word per minute send speed. This would mean basically that a 250 word signal would be sent within 40 or 50 seconds. Insufficient time for a shipboard DF unit to get a fix. DF units on mainland Britain would not get the necessary cross bearings to get a proper fix, so Lutjens did not betray his position with that or any other signal.

Vic Dale

So all the histories claiming that USN/RN/RCN use of HF-DF was important in the battle against the
U-boots are incorrect?

The DF work against the U-Boats did not take off properly until 1942, though a clandestine DF station was installed on Southern Greenland circa November-December 1940, which was able to transmit the presence of U-Boats so convoys could detour and avoid them. The type of DF tracking installation would have been of the rudimentary type and not a match for the super-fast multi-directional ariels in use at mainland stations, which could home in on a transmisson and give the bearing within 3 seconds.

There is a big difference between warning of the presence of U-Boats by DF tracking efforts and actually hunting them by use of DF. Usually a DF cut was not closer than 200 miles, meaning that ships would have to concentrate in the area on the chance that the boat would transmit again, which happily they often did. It was only when the superfast ariels were adapted for service in a warship that the U-Boats were decisively defeated by the surface-hunting groups, until then it was aerial attack especially when using radar which produced the best results and of course a combination of both.

There is the possibility of a "cut" from Greenland which would make the cross-bearings sufficiently accurate to give a pin-point. It is also possible that DF cross bearings on "Bismarck" came from the USA and not Britain, though nothing of this could be made public and may even not have been made public yet, due to the fact that the USA was not in the war at the time of Rhine Ubung and Greenland was Danish territory, which after the occupation of Denmark would legally cede to German ownership.

Even with a cut from Greenland using the British tracking stations, with Bismarck 2000 miles out into the Atlantic one degree of error would cover 400 miles of latitude, so anything from Britain would be virtually useless. A cut using Greenland against Washington, which I believe was the nearest US station would give an error of 200 miles per degree. We need also to consider Ionospheric interference which could cause deviation of up to 8 degrees, so DF on a lone German vessel which had been lost 5 hours previously would be unlikely to get nearer than her farthest-on if she steamed at high speed in any direction.

The problem with getting a DF cut is clearly identifying the source as an enemy vessel - surface unit or U-Boat - and it is known that at least one DF pin-point for Bismarck turned out to be a U-Boat reporting Victorious to SKL. The tracking reports got no nearer than saying they were certain it was the same ship which had been transmitting after the air attack of the previous evening at 2330. According to Bismarck's reconstructed War Diary Bismarck did not report the attack until 0038 - at least an hour later.

NB. the diary shows a time of transmission at 2338, but German time in Bismarck was one hour behind that of the British.

Very likely the DF tracking stations had picked up on a U-boat making her nightly report or responding to signals. The charts of the operation show U-Boats, but those would only be boats with torpedoes able to be used on the patrol lines set up by Lutjens. Very likely then the DF work was all done on U-Boats, as Bismarck actually made surprisingly few signals, many of which would be of the 5 letter Kurtzignalle type and useless for shipboard DF tracking.

There is also the possibility that Lutjens transferred his call sign temporarily to a U-Boat, specifically so she could transmit a signal which could be picked up. There is some hint of this as a possibility, though not much credibility is given to it.

Vic Dale

[lwd]

Didn't the British have listening stations on Iceland?

[Karl Heidenreich]

lwd:

Didn't the British have listening stations on Iceland?

That´s how they triangulate, isn´t it?

[Nearchus]

Didn't the British have listening stations on Iceland?

The stations at Iceland and Gibraltar did not receive the transmissions and were unable to provide a "cut".