WBS 6 München and HMS Somali - may 1941.







PG 465



"Nordsee" Deutsche Hochseefischerei, Wesermünde










17 crew
4 meteorologist

Operation "München" 1941

Iceland/Jan Mayen area (5.1941) - WBS
Caught on 7th May 1941 by HMS Somali south east of Iceland. Reported sunk to deceive the Germans and keep the Enigma code un compromised. Sold to Faroe Islands 1943 as "Froyen".




Enigma cipher machine




Capture of the Enigma codes

It was Harry Hinsley (Bletchley Park) who, at the end of April 1941, identified the Enigma's fatal flaw the same enigma code books used on the heavily armed U Boats that were so difficult to capture were also being used aboard isolated and unprotected trawlers. The trawlers, which were transmitting weather reports to the Germans, were in their turn being sent naval enigma messages.

Although the weather ships were not enciphering their weather reports on enigma machines, they had to have one of the machines on board if they were to decode the enigma signals transmitted to them. This was an act of almost unbelievable folly since, if the code books could be captured from one of these vulnerable trawlers, the naval enigma system, used by the U Boats, Nazi Germany's most effective weapon, would be compromised. Hinsley had discovered Enigma's Achilles heel! He immediately told the Admiralty what he had found out. Then he explained how the discovery might best be exploited. If the Royal Navy were to send a warship to board one of the weather ships, the German crew would doubtless have time to throw their current enigma settings into the sea before they were boarded. However, Hinsley was almost certain that the next month's Enigma settings would be locked in a safe. That being the case, he reasoned, if the Germans were frightened sufficiently by the warships guns, the locked up codebooks might well be forgotten when the ships were abandoned. The Admiralty accepted Hinsley's hypothesis. At the beginning of May 1941, no fewer than seven destroyers and cruisers were sent to the northeast of Iceland where the München, one of the weather ships, was operating. In the course of the raid, the weather ship, and the Enigma settings for June 1941, were captured. As a result of this planned capture, naval enigma messages transmitted during June 1941 were read almost as soon as they were sent.

But halfway through June 1941 the German's had replaced the bigram tables worked out so painstakingly by the British code breakers. This was a serious problem for the code breakers. Since Bletchley Park needed to read Enigma messages for about a month to be able to construct the new tables, and since the code breakers only had Enigma settings for the two week period ending at the end of June, there would be a code breaking blackout unless further settings were captured. But Hinsley and the Admiralty were concerned that capturing another weather ship might give the game away. There was no point in seizing the settings if the Germans immediately altered them because they knew they had been captured. So there were agonised discussions about what to do before the Admiralty decided to take a risk. On June 25th 1941 four warships set out from Scapa Flow to capture the codebooks from the Lauenburg, another weather ship operating north of Iceland, which Hinsley had selected. On the way Kim Skipwith, the Commander of the Destroyer HMS Tartar told his men that they were looking for a meteorological ship that was providing the Luftwaffe with weather reports. "If you chaps don't want your homes to be bombed, you'd better find her", he told them. He then warned Tom Kelly, his chief gunners mate, that when they found the ship he would be instructed to open fire but he must on no account hit the target. "That'll be very easy", Kelly retorted impudently. "I just want to encourage the crew to abandon ship, pronto", Skipwith explained.

At about 7pm on June 28th, a lookout on Tartar shouted "There's something over there, behind that iceberg!". That something was the Lauenburg. Shortly after Kelly's gunners opened fire, two lifeboats full of the Lauenburg's crew were seen being rowed away from the weather ship. Minutes later Tartar steamed alongside and a boarding party led by Lieutenant Hugh Wilson leapt aboard. They were joined by Allan Bacon, a Naval intelligence officer. "There's nothing much here", Wilson told him. Nodding dismissively at the disorganized piles of paper lying in the charthouse and on the deck, he added "You don't want this rubbish do you?". To which Bacon replied that he wanted it all and declared himself satisfied only when all the paper had been bagged and taken to Tartar. Only then was Kelly instructed to fire on and sink the Lauenburg. On the journey back to Scapa Flow, Bacon closeted himself in the Officer's day cabin to sort out the documents. Wilson looked in from time to time to offer him a cup of gin, but Bacon refused to be distracted. When Tom Kelly popped his head round the door and asked Bacon if he had found what he was looking for, Bacon, who had disappointed the Task Forces Commander by not bringing back an enigma machine said, "No, but I've found something a damn sight more important". Among the mass of charts and signaling papers he had come across three loose sheets that Hinsley had hoped he would find. Two of these were headed Steckerverbindungen (plug connections) and one was a list of the Innere Finstellung (inner settings) i.e.: the enigma wheel order, and the settings for the rings around the wheels that could be altered only by fiddling around inside the Enigma machine.

It was thanks to these documents that naval Enigma messages were read throughout most of July 1941.

No covers

Feldpost Nr.
M 30 086

Wetterbeobachtungsschiff "München"
Wetterbeobachtungsschiff No. 6

From: "Die deutsche Feldpostübersicht 1939-1945" by Norbert Kannapin.


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