May 7, 1941 An Enigma Solved

On this day in 1941, as you can read in the item below, the British destroyer HMS Somali captured the German weather ship München off of Iceland.

Today in World War II History—May 7, 1941

With the ship the British also captured her July Enigma code book.  In fact, she was targeted for that.

Benchley Park had figured out that the fatal flaw of Enigma was the universality of the code books and they guessed that weather ships would have them, even though they didn't transmit in code, and that they'd have the following month's in a safe.  The plan was to fire over a weather ship and frighten the crew in the hopes they'd fail to dump the second book, which they in fact did.

Weather ships were a critical part of the German U-boat campaign but also a weakness in it.  In the days before satellite weather forecasting, weather forecasting relied upon weather readings and observations.  This meant that the Germans had no choice but to put weather ships in the North Atlantic and to also land men on Iceland and Greenland, and even Labrador. All of these efforts were vulnerable to Allied detection and they had to rely on the remoteness of their locations for protection.

On the same day, the Germans released the film Sieg Im Westen (Victory in the West).  It proved to be premature.

Also on this day, the Royal Air Force took its first delivery of B-17s.  The RAF would never use a large number of the American bomber, but they did employ some.  They would not see combat until July, when they were used in a high altitude bombing raid which served to confirm in British minds that daylight bombing was too costly.

The Battle of South Shanxi began in China and would result in one of the worst defeats for the Nationalist Chinese in the Second World War.  Critical to the result, Communist Chinese forces refused to come to the aid of encircled Nationalist Chinese forces due to embittered communist feelings over the New Fourth Army Incident of earlier that year.

That earlier incident had occurred in early 1941 and saw the Chinese communist sustain about 7,000 casualties at Nationalist Chinese hands. Accounts of the incident vary enormously and it is therefore almost impossible to figure out who broke the truce between the Nationalist and the Communist that was brokered in order to contest the Japanese, the bigger enemy.   At any rate, the Nationalist sustained over 100,000 casualties in the South Shanxi battle, so the Communist more than evened the score.