The spooks of Ultra (GC&CS at Bletchley Park) succeeded in deciphering many Wehrmacht messages encrypted on the standard versions of the Enigma Machine, but never could decipher those encrypted on the Turtleback version.
This had something to do with allowing the turtle to enter the initial settings and required an operator skilled in Turtletalk to obtain those initial settings from the turtle thus adding yet another layer of security. Bletchley Park did not have a Turtletalk translator which completely stymied their attempts at deciphering those communications.
After the war the cadre of Nazi coding turtles and their talkers were captured and tried as war criminals. The talkers were sentenced to write for Benny Hill since the court found they were insane from the start, and the turtles were sold to Polly Bergen where their unction lived on in her Oil of Turtle line of cosmetics...
I have more fractured historical facts to relate for this story but I have been summoned for a secret mission to the field East of the Silo. You know, where the assault weapons are buried...