The Weather Ships and Enigma
The British cryptologist Harry Hinsley, then working at Bletchley Park realised at the end of April 1941 that the German weather ships, usually isolated and unprotected trawlers, were using the same Enigma code books as were being used on the heavily armed U Boats. The trawlers, which were transmitting weather reports to the Germans, were in turn being sent naval Enigma messages.
Although the weather ships did not transmit enciphered weather reports on Enigma machines, they still needed to have one of the machines on board if they were to decode the Enigma signals transmitted to them. Hinsley realised that if the code books could be captured from one of these vulnerable trawlers, the naval Enigma system could be broken, with British intelligence able to decipher messages to U-boats and discover their locations. The problem remained that if the navy were to attempt to capture one of the weatherships, the German crew would have time to throw their current Enigma settings into the sea before they were boarded. Hinsley instead reasoned that the following month's Enigma settings would be locked in a safe aboard the ship, and could potentially be overlooked if the Germans were forced to hastily abandon ship. On being informed, the Admiralty despatched seven destroyers and cruisers to the northeast of Iceland at the beginning of May 1941. The target was the München, one of the weather ships operating in the area. In the course of the raid, the weather ship, and the Enigma settings for June 1941 were captured. As a result, naval Enigma messages transmitted during June 1941 could be quickly deciphered.
Halfway through June 1941 the Germans replaced the bigram tables used in Enigma. This would have resulted in a codebreaking blackout unless further settings could be captured. Hinsley and the Admiralty were concerned that capturing another weather ship might alert the Germans to their vulnerability and cause them to immediately alter them again. It was eventually decided to take the risk and on 25 June 1941 four warships, the light cruiser HMS Nigeria and the destroyers HMS Tartar, HMS Jupiter and HMS Bedouin, were despatched from Scapa Flow to capture the codebooks from the Lauenburg, another weather ship operating north of Iceland, which Hinsley had selected.
Read more about this topic: German Weather Ship Lauenburg
Famous quotes containing the words weather, ships and/or enigma:
“What
One believes is what matters. Ecstatic identities
Between one’s self and the weather and the things
Of the weather are the belief in one’s element,
The casual reunions, the long-pondered
Surrenders, the repeated sayings that
There is nothing more and that it is enough....”
—Wallace Stevens (1879–1955)
“I saw three ships come sailing by,
Come sailing by, come sailing by,
I saw three ships come sailing by,
On Christmas Day in the morning.”
—Unknown. As I Sat on a Sunny Bank. . .
Oxford Book of Light Verse, The. W. H. Auden, ed. (1938)
“His moving impulse is no flabby yearning to teach, to expound, to make simple; it is that “obscure inner necessity” of which Conrad tells us, the irresistible creative passion of a genuine artist, standing spell-bound before the impenetrable enigma that is life, enamoured by the strange beauty that plays over its sordidness, challenged to a wondering and half-terrified sort of representation of what passes understanding.”
—H.L. (Henry Lewis)