Luftwaffe Personnel spying for Allies?

[John Beaman]

Nick is correct in that how Ultra was solved is a very complex matter. It was never consistently solved in the sense that every captured message was solved. This is especially true with German Naval coding.

Much of the initial breakthrough came from manual and primitive computer (these were actually banks of linked enigma machines, endlessly churning through key punched code for common links) analysis as Nick says along with learning how the enigma machine was used and set on a daily basis. Sometimes, rarely, they guessed right, but more often German operators were lazy and used settings that could be seen as repeats or matched up to other known settings and then guessed at. The Luftwaffe was nortorious for:

• Using the radio for almost everything, thus giving more opportunity for the British to see traffic and analyse it for repetitive groups that might be deciphered.
• Using girlfriends names or repeat settings that allowed for deciphering settings on the wheels on a daily basis. I.e., their radio discipline was poor, helping the British.

The German Navy was much more disciplined in changing settings, using random settings and eventually even added more wheels to the machine, making deciphering settings much more difficult. In fact while after 1940 Luftwaffe traffic was deciphered quite regularly, the deciphering the Navy traffic was a hit and miss affair until mid-1943 when the combination of Ultra, Huff-Duff, long range patrol aircraft and the beginnings of the escort carrier deployment finally did in the U-boats.

Ultra is a complex business. There are many excellent books out there, including the ones Nick mentioned. To understand how complex the accomplishment of deciphering was, you almost have to read them all.